The Project Gutenberg EBook of Scientific American Supplement, No. 717,
September 28, 1889, by Various
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Title: Scientific American Supplement, No. 717, September 28, 1889
Author: Various
Release Date: February 12, 2006 [EBook #17755]
Language: English
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SCIENTIFIC AMERICAN SUPPLEMENT NO. 717
NEW YORK, SEPTEMBER 28, 1889.
Scientific American Supplement. Vol. XXVIII., No. 717.
Scientific American established 1845.
Scientific American Supplement, $5 a year.
Scientific American and Supplement, $7 a year.
* * * * *
TABLE OF CONTENTS.
I. CIVIL ENGINEERING.--The Girard Hydraulic Railway.--One of
the great curiosities of the Paris exposition, the almost
frictionless railway, with sectional illustrations of its
structure.--8 illustrations. 11451
II. ELECTRICITY.--Early Electric Lighting.--Electric lighting in
Salem in 1859, a very curious piece of early history. 11458
Electric Motor for Alternating Currents.--A motor on an
entirely new principle for the application of the alternating
current with results obtained, and the economic outlook of
the invention. 11458
Portable Electric Light.--A lamp for military and other use,
in which the prime motor, including the boiler and the lamp
itself, are carried on one carriage.--1 illustration. 11458
The Electric Age.--By CHARLES CARLETON COFFIN.--A short
_resume_ of the initial achievements of modern
electricity. 11458
III. GEOLOGY.--The Fuels of the Future.--A prognosis of the future
prospect of the world as regards a fuel supply, with a
special reference to the use of natural gas. 11457
IV. MISCELLANEOUS.--Preservation of Spiders for the Cabinet.--A
method of setting up spiders for preservation in the cabinet,
with formulæ of solutions used and full details of the
manipulation.--1 illustration. 11461
The Ship in the New French Ballet of the "Tempest."--A
curious example of modern scenic perfection, giving the
construction and use of an appliance of the modern ballet.--5
illustrations. 11450
V. NAVAL ENGINEERING.--Crank and Screw Shafts of the Mercantile
Marine.--By G. W. MANUEL.--This all-important subject of
modern naval engineering treated in detail, illustrating the
progress of the present day, the superiority of material and
method of using it, with interesting practical examples.--1
illustration. 11448
Experimental Aid in the Design of High Speed Steamships.--By
D. P.--A plea for the experimental determination of the
probable speed of ships, with examples of its application in
practice. 11449
Forging a Propeller Shaft.--How large steamer shafts are
forged, with example of the operation as exhibited to the
Shah of Persia at Brown & Co.'s works, Sheffield, England.--1
illustration. 11447
The Naval Forges and Steel Works at St. Chamond.--The forging
of a piece of ordnance from a 90 ton ingot of steel, an
artistic presentation of the subject.--1 illustration. 11447
VI. PHOTOGRAPHY.--The Pyro Developer with Metabisulphite of
Potash.--By Dr. J. M. EDER.--A new addition to the pyro
developer, with formulæ and results. 11462
VII. PHYSICS.--Quartz Fibers.--A lecture by Mr. C. V. BOYS on his
famous experiments of the production of microscopic fibers,
with enlarged illustrations of the same, and a graphic
account of the entire subject.--7 illustrations. 11452
The Modern Theory of Light.--By Prof. OLIVER LODGE.--An
abstract of a lecture by the eminent investigator and
expositor of Prof. Hertz's experiments, giving a brief review
of the present aspect of this absorbing question. 11459
VIII. PHYSIOLOGY.--Heat in Man.--Experiments recently made by Dr.
Loewy on the heat of the human system.--Described and
commented on by Prof. ZUNTZ. 11461
IX. SANITATION.--On Purification of Air by Ozone--with an Account
of a New Method.--By Dr. B. W. RICHARDSON.--A very important
subject treated in full, giving the past attempts in the
utilization of ozone and a method now available. 11460
X. TECHNOLOGY.--Alkali Manufactories.--Present aspect of the
Leblanc process and the new process for the recovery of
sulphur from its waste. 11457
Dried Wine Grapes.--The preparation of the above wine on a
large scale in California, with full details of the process
adopted. 11461
The Production of Ammonia from Coal.--By LUDWIG MOND.--A
valuable review of this important industry, with actual
working results obtained in carrying out a retort process.--2
illustrations. 11454
Nature, Composition, and Treatment of Animal and Vegetable
Fabrics.--The history of fabrics and fibers in the vegetable
and animal world, their sources, applications, and
treatments. 11453
Walnut Oil.--By Thomas T. P. BRUCE WARREN.--An excellent oil
for painters' use, with description of a simple method for
preparing it on a small scale. 11462
* * * * *
THE NAVAL FORGES AND STEEL WORKS AT ST. CHAMOND.
With the idyls and historic or picturesque subjects that the Universal
Exposition gives us the occasion to publish, we thought we would make
a happy contrast by selecting a subject of a different kind, by
presenting to our readers Mr. Layraud's fine picture, which represents
the gigantic power hammer used at the St. Chamond Forges and Steel
Works in the construction of our naval guns. By the side of the
machinery gallery and the Eiffel tower this gigantic apparatus is well
in its place.
[Illustration: UNIVERSAL EXPOSITION--BEAUX ARTS--MARINE IRON AND STEEL
WORKS AT SAINT CHAMOND--PRESENTATION OF A PIECE OF ORDNANCE UNDER THE
VERTICAL HAMMER.--PICTURE BY M. JOSEPH LAYRAUD.]
The following is the technical description that has been given to us
to accompany our engraving: In an immense hall, measuring 260 ft. in
length by 98 ft. in width, a gang of workmen has just taken from the
furnace a 90 ton ingot for a large gun for an armor-clad vessel. The
piece is carried by a steam crane of 140 tons power, and the men
grouped at the maneuvering levers are directing this incandescent mass
under the power hammer which is to shape it. This hammer, whose huge
dimensions allow it to take in the object treated, is one of the
largest in existence. Its striking mass is capable of reaching 100
tons, and the height of the fall is 16 ft. To the left of the hammer
is seen a workman getting ready to set it in motion. It takes but one
man to maneuver this apparatus, and this is one of the characteristic
features of its construction.
The beginning of this hammer's operation, as well as the operations of
the forge itself, which contains three other hammers of less power,
dates back to 1879. It is with this great hammer that the largest
cannons of the naval artillery--those of 16 inches--have been made
(almost all of which have been manufactured at St. Chamond), and
those, too, of 14, 13, and 12 inches. This is the hammer, too, that, a
few months ago, was the first to be set at work on the huge 13 in.
guns of new model, whose length is no less than 52 ft. in the rough.
Let us add a few more figures to this account in order to emphasize
the importance of the installations which Mr. Layraud's picture
recalls, and which our great French industry has not hesitated to
establish, notwithstanding the great outlay that they necessitated.
This huge hammer required foundations extending to a depth of 32 ft.,
and the amount of metal used in its construction was 2,640,000 pounds.
The cost of establishing the works with all the apparatus contained
therein was $400,000.--_Le Monde Illustré._
* * * * *
FORGING A PROPELLER SHAFT.
During the recent visit of the Shah of Persia to England, he visited,
among other places, the great works of John Brown & Co., at Sheffield,
and witnessed the pressing of a propeller shaft for one of the large
ocean steamships. The operation is admirably illustrated in our
engraving, for which we are indebted to the _Illustrated London News_.
[Illustration: PROPELLER SHAFT BEING PRESSED AT MESSRS. JOHN BROWN &
CO.'S WORKS, SHEFFIELD.]
* * * * *
CRANK AND SCREW SHAFTS OF THE MERCANTILE MARINE.[1]
By G. W. MANUEL.
[Footnote 1: A paper read before the Institute of Marine
Engineers, Stratford, 1889.]
Being asked to read a paper before your institute, I have chosen this
subject, as I think no part of the marine engine has given so much
trouble and anxiety to the seagoing engineer; and from the list of
shipping casualties in the daily papers, a large proportion seem due
to the shafting, causing loss to the shipowner, and in some instances
danger to the crew. My endeavor is to put some of the causes of these
casualties before you, also some of the remedies that have tended to
reduce their number. Several papers have been read on this subject,
chiefly of a theoretical description, dealing with the calculations
relating to the twisting and bending moments, effects of the angles of
the cranks, and length of stroke--notably that read by Mr. Milton
before the Institute of Naval Architects in 1881. The only _practical_
part of this paper dealt with the possibility of the shafts getting
out of line; and regarding this contingency Dr. Kirk said that "if
superintendent engineers would only see that the bearings were kept in
line, broken crank and other shafts would not be so much heard of." Of
course this is one of those statements made in discussions of this
kind, for what purpose I fail to see, and as far as my own experience
goes is _misleading_; for having taken charge of steamers new from the
builders' hands, when it is at least expected that these shafts would
_be in line_, the crank shaft bearings heated very considerably, and
_continued_ to do so, rendering the duration of life of the crank
shaft a short one; and though they were never what is termed out of
line, the bearings could _not_ be kept cool without the use of sea
water, and occasionally the engines had to be stopped to cool and
smooth up the bearing surfaces, causing delays, worry, and anxiety,
for which the engineer in charge was in no way responsible. Happily
this state of what I might call _uncertainties_ is being gradually
remedied, thanks being largely due to those engineers who have the
skill to suggest improvements and the patience to carry them out
against much opposition.
These improvements in many instances pertain to the engine builder's
duties, and are questions which I think have been treated lightly;
notably that of insufficient bearing surface, and one of the principal
causes of hot bearings, whereby the oil intended for lubrication was
squeezed out, and the metal surfaces brought too close in contact; and
when bearings had a pressure of 200 lb. per square inch, it has been
found that not more than 120 lb. per square inch should be exerted to
keep them cool (this varies according to the material of which the
bearing is composed), without having to use sea water and prevent them
being ground down, and thus getting out of line. I have known a
bearing in a new steamer, in spite of many gallons of oil wasted on
it, wear down one-eighth of an inch in a voyage of only 6,000 miles,
from insufficiency of bearing surface.
Several good rules are in use governing the strength of shafts, which
treat of the diameter of the bearings only and angles of the cranks;
and the engine builder, along with the ship owner, has been chary of
increasing the surfaces by lengthening the bearings; for to do this
means increase of space taken up fore and aft the vessel, besides
additional weight of engine. Engine builders all aim in competing to
put their engines in less space than their rivals, giving same power
and sometimes more. I think, however, this inducement is now more
carefully considered, as it has been found more economical to give
larger bearing surfaces than to have steamers lying in port, refitting
a crank shaft, along with the consequences of heavy bills for salvage
and repairs, also the risk of losing the steamer altogether.
Proportioning the bearings to the weights and strains they have to
carry has also been an improvement. The different bearings of marine
engines were usually made alike in surface, irrespective of the work
each had to do, with a view to economy in construction.
In modern practice the after bearings have more surface than the
forward, except in cases where heavy slide-valve gear has to be
supported, so that the wear down in the whole length of the shaft is
equal, thus avoiding those alternate bending strains at the top and
bottom of the stroke every revolution. Another improvement that has
been successfully introduced, adding to the duration of life of crank
shafts, is the use of white bearing metal, such as Parson's white
brass, on which the shafts run smoothly with less friction and
tendency to heat, so that, along with well proportioned surfaces, a
number of crank shafts in the Peninsular and Oriental Co.'s service
have not required lining up for eight years, and I hope with care may
last till new boilers are required. Large and powerful steamers can be
driven full speed from London to Australia and back without having any
water on the bearings, using oil of only what is considered a moderate
price, allowing the engineer in charge to attend to the economical
working of both engines and boilers (as well as many other engines of
all kinds now placed on board a large mail and passenger steamer),
instead of getting many a drenching with sea water, and worried by
close attention to one or two hot bearings all the watch. Compare
these results with the following: In the same service in 1864, and
with no blame to the engineer in charge, the crank shaft bearings of a
screw steamer had to be lined up every five days at intermediate
ports, through insufficient bearing surfaces. Sea water had
continually to be used, resulting in frequent renewal of crank shaft.
Steamers can now run 25,000 miles without having to lift a bearing,
except for examination at the end of the voyage. I would note here
that the form of the bearings on which the shafts work has also been
much improved. They are made more of a _solid character_, the metal
being more equally disposed _round_ the shaft, and the use of gun
metal for the main bearings is now fast disappearing. In large engines
the only metals used are cast iron and white brass, an advantage also
in reducing the amount of wear on the recess by corrosion and grinding
where sea water was used often to a considerable extent.
[Illustration: Fig. 1
Fig. 2]
Figs. No. 1 and No. 2 show the design of the old and new main
bearings, and, I think, require but little explanation. Most of you
present will remember your feelings when, after a hot bearing, the
brasses were found to be cracked at top and bottom, and the trouble
you had afterward to keep these brasses in position. When a smoking
hot bearing occurred, say in the heating of a crank pin, it had the
effect of damaging the material of the shaft more or less, according
to its original soundness, generally at the fillets in the angles of
the cranks. For when the outer surface of the iron got hot, cold
water, often of a low temperature, was suddenly poured on, and the hot
iron, previously expanded, was suddenly contracted, setting up strains
which in my opinion made a small tear transversely where the metal was
_solid_; and where what is termed lamination flaws, due to
construction, existed, these were extended in their natural direction,
and by a repetition of this treatment these flaws became of such a
serious character that the shafts had to be condemned, or actually
gave way at sea. The introduction of the triple expansion engine, with
the three cranks, gave better balance to the shaft, and the forces
acting in the path of the crank pin, being better divided, caused more
regular motion on the shaft, and so to the propeller. This is
specially noticeable in screw steamers, and is taken advantage of by
placing the cabins further aft, nearer the propeller, the stern having
but little vibration; the dull and heavy surging sound, due to unequal
motions of the shaft in the two-crank engines, is exchanged for a more
regular sound of less extent, and the power formerly wasted in
vibrating the stern is utilized in propelling the vessel. In spite of
all these improvements I have mentioned, there remains the serious
question of defects in the material, due to variety of quality and the
extreme care that has to be exercised in all the stages during
construction of crank or other shafts built of iron. Many shafts have
given out at sea and been condemned, through no other cause than
_original defects_ in their construction and material.
The process of welding and forging a crank shaft of large diameter now
is to make it up of so many small _pieces_, the _best shafts_ being
made of what is termed scrap, representing thousands of small pieces
of selected iron, such as cuttings of old iron boiler plates,
cuttings off forgings, old bolts, horseshoes, angle iron, etc., all
welded together, forged into billets, reheated, and rolled into bars.
It is then cut into lengths, piled, and formed into slabs of suitable
size for welding up into the shafts. No doubt this method is
preferable to the old method of "fagoting," so called, as the iron
bars were placed side by side, resembling a bundle of fagots of about
18 or 20 inches square.
The result was that while the outside bars would be welded, the inside
would be improperly welded, or, the hammer being weak, the blow would
be insufficient to secure the proper weld, and it was no uncommon
thing for a shaft to break and expose the internal bars, showing them
to be quite separate, or only partially united. This danger has been
much lessened in late years by careful selection of the materials,
improved methods of cleaning the scrap, better furnaces, the use of
the most suitable fuels, and more powerful steam hammers. Still, with
all this care, I think I may say there is not a shaft without flaws or
defects, more or less, and when these flaws are situated in line of
the greatest strains, and though you _may not_ have a hot bearing,
they often extend until the shaft becomes unseaworthy.
[Diagrams shown illustrated the various forms of flaws.] These flaws
were not observable when the shafts were new, although carefully
inspected. They gradually increased under strain, came to the outside,
and were detected. Considerable loss fell upon the owners of these
vessels, who were in no way to blame; nor could they recover any money
from the makers of the shafts, who were alone to blame. I am pleased
to state, and some of the members here present know, that considerable
improvement has been effected in the use of better material than iron
for crank shafts, by the introduction of a special mild steel, by
Messrs. Vickers, Sons & Co., of Sheffield, and that instead of having
to record the old familiar defects found in iron shafts, I can safely
say no flaws have been observed, when new or during eight years
running, and there are now twenty-two shafts of this mild steel in the
company's service.
I may here state that steel was used for crank shafts in this service
in 1863, as then manufactured in Prussia by Messrs. Krupp, and
generally known as _Krupp's steel_, the tensile strength of which was
about 40 tons per square inch, and though free from flaws, it was
unable to stand the fatigue, and broke, giving little warning. It was
of too brittle a nature, more resembling chisel steel. It was broken
again under a falling weight of 10 cwt. with a 10 ft. drop = 12½ tons.
The mild steel now used was first tried in 1880. It possessed tensile
strength of 24 to 25 tons per square inch. It was then considered
advisable not to exceed this, and err rather on the safe side. This
shaft has been in use eight years, and no sign of any flaw has been
observed. Since then the tensile strength of mild steel has gradually
been increased by Messrs. Vickers, the steel still retaining the
elasticity and toughness to endure fatigue. This has only been arrived
at by improvements in the manufacture and more powerful and better
adapted hammers to forge it down from the large ingots to the size
required. The amount of work they are now able to subject the steel to
renders it more fit to sustain the fatigue such as that to be endured
by a crank shaft. These ingots of steel can be cast up to 100 tons
weight, and require powerful machines to deal with them. For shafts
say of 20 inches diameter, the diameter of the ingot would be about 52
inches. This allows sufficient work to be put on the couplings, as
well as the shaft. To make solid crank shafts of this material, say of
19 inches diameter, the ingot would weigh 42 tons, the forging, when
completed, 17 tons, and the finished shaft 11¾ tons; so that you see
there is 25 tons wasted before any machining is done, and 5¼ tons
between the forging and finished shaft. This makes it very expensive
for solid shafts of large size, and it is found better to make what is
termed a _built shaft_; the cranks are a little heavier, and engine
framings necessarily a little wider, a matter comparatively of little
moment. I give you a rough drawing of the hydraulic hammer, or
strictly speaking a _press_, used by Messrs. Vickers in forging down
the ingots in shafts, guns, or other large work. This hammer can give
a squeeze of 3,000 tons. The steel seems to yield under it like tough
putty, and, unlike the steam hammer, there is no _jarring_ on the
material, and it is manipulated with the same ease as a small hammer
by hydraulics.
The tensile strength of steel used for shafts having increased from 24
to 30 tons, and in some cases 31 tons, considering that this was 2
tons above that specified, and that we were approaching what may be
termed _hard steel_, I proposed to the makers to test this material
beyond the usual tests, viz., tensile, extension, and cold bending
test. The latter, I considered, was much too easy for this fine
material, as a piece of fair iron will bend cold to a radius of 1½
times its diameter or thickness, without fracture; and I proposed a
test more resembling the fatigue that a crank shaft has sometimes to
stand, and more worthy of this material; and in the event of its
standing this successfully, I would pass the material of 30 or 31 tons
tensile strength. Specimens of steel used in the shafts were cut off
different parts--crank pins and main bearings--(the shafts being built
shafts) and roughly planed to 1½ inches square, and about 12 inches
long. They were laid on the block as shown, and a cast iron block,
fitted with a hammer head ½ ton weight, let suddenly fall 12 inches,
the block striking the bar with a blow of about 4 tons. The steel bar
was then turned upside down, and the blow repeated, reversing the
piece every time until fracture was observed, and the bar ultimately
broken. The results were that this steel stood 58 blows before showing
signs of fracture, and was only broken after 77 blows. It is
noticeable how many blows it stood after fracture. A bar of good
wrought iron, undressed, of same dimensions, was tried, and broke the
first blow. A bar cut from a piece of iron to form a large chain,
afterward forged down and only filed to same dimensions, broke at 25
blows. I was well satisfied with the results, and considered this
material, though possessing a high tensile strength, was in every way
suitable for the construction and endurance required in crank shafts.
Sheet No. 1 shows you some particulars of these tests:
Tensile Elong. Fractured Broke Fall
Tons. in 5" Bend. Blows. Blows. In.
A = 30.5 28 p. c. Good 61 78 12
In order to test the comparative value of steel of 24¾ up to 35 tons
tensile strength, I had several specimens taken from shafts tested in
the manner described, which may be called a _fatigue_ test. The
results are shown on the same sheet:
B = 24½ Good 64 72 7
B -- -- -- 48 54 12
C = 27 25.9 p. c. Good 76 81 12
D = 29.6 28.4 p. c. Good 71 78 12
E = 30.5 28.9 p. c. Good 58 77 12
F = 35.5 20 p. c. Good 80 91 12
The latter was very tough to break. Specimen marked A shows one of
these pieces of steel. I show you also fresh broken specimens which
will give you a good idea of the beautiful quality of this material.
These specimens were cut out of shafts made of Steel Co. of Scotland's
steel. I also show you specimens of cold bending:
Tensile Elong. Fractured Broke Fall
Tons. in. 5" Bend. Blows. Blows. In.
G = 30.9 27½ p. c. Good 59 66 12
H = 29.3 30 p. c. Good 66 90 12
I = 28.9 28.9 p. c. Good 53 68 12
I think all of the above tests show that this material, when carefully
made and treated with sufficient mechanical work on forging down from
the ingot, is suitable up to 34 tons for crank shafts; how much higher
it would be desirable to go is a question of superior excellence in
material and manufacture resting with the makers. I would, however,
remark that no allowance has been made by the Board of Trade or Lloyds
for the excellence of this material above that of iron. I was
interested to know how the material in the best iron shafts would
stand this fatigue test compared with steel, and had some specimens of
same dimensions cut out of iron shafts. The following are the results:
Best iron, three good qualities, rolled into flat bars, cut and made
into 4½ cwt. blooms.
J = 18.6 24.3 p. c. Good 17 18 12
Made of best double rolled scrap, 4½ cwt. blooms.
K = 22 32½ p. c. Good 21 32 12
You will see from these results that steel stood this fatigue test,
Vickers' 73 per cent. and Steel Co.'s 68 per cent., better than iron
of the best quality for crank shafts; and I am of opinion that so long
as we use such material as these for crank shafts, along with the
present rules, and give ample _bearing surface_, there will be few
broken shafts to record.
I omitted to mention that built shafts, both of steel and iron, of
large diameter, are now in general use, and with the excellent
machines, and under special mechanics, are built up of five separate
pieces in such a rigid manner that they possess all the solidity
necessary for a crank shaft. The forgings of iron and steel being much
smaller are capable of more careful treatment in the process of
manufacture. These shafts, for large mail steamers, when coupled up,
are 35 feet long, and weigh 45 tons. They require to be carefully
coupled, some makers finishing the bearings in the lathe, others
depend on the excellence of their work in each piece, and finish each
complete. To insure the correct centering of these large shafts, I
have had 6 in. dia. recesses ¾ inch deep turned out of each coupling
to one gauge and made to fit one disk. Duplicate disks are then fitted
in each coupling, and the centering is preserved, and should a spare
piece be ever required, there is no trouble to couple correctly on
board the steamer.
The propeller shaft is generally made of iron, and if made _not less_
than the Board of Trade rules as regards diameter, of the best iron,
and the gun metal liners carefully fitted, they have given little
trouble; the principal trouble has arisen from defective fitting of
the propeller boss. This shaft working in sea water, though running in
lignum vitæ bearings, has a considerable wear down at the outer
bearings in four or five years, and the shaft gets out of line. This
wear has been lessened considerably by fitting the wood so that the
grain is endway to the shaft, and with sufficient bearing surface
these bearings have not required lining up for nine years. It is,
however, a shaft that cannot be inspected except when in dry dock, and
has to be disconnected from the propeller, and drawn inside for
examination at periods suggested by experience. Serious accidents have
occurred through want of attention to the examination of this shaft;
when working in salt water, with liners of gun metal, galvanic action
ensues, and extensive corrosion takes place in the iron at the ends of
the brass liners, more especially if they are faced up at right angles
to the shaft. Some engineers have the uncovered part of the shaft
between the liners, inside the tube, protected against the sea water
by winding over it tarred line. As this may give out and cause some
trouble, by stopping the water space, I have not adopted it, and shall
be pleased to have the experience of any seagoing engineer on this
important matter. A groove round the shaft is formed, due to this
action, and in some cases the shaft has broken inside the stern tube,
breaking not only it, but tearing open the hull, resulting in the
foundering of the vessel. Steel has been used for screw shafts, but
has not been found so suitable, as it corrodes more rapidly in the
presence of salt water and gun metal than iron, and unless protected
by a solid liner for the most part of its length, a mechanical feat
which has not yet been achieved in ordinary construction, as this
liner would require to be 20 ft. long. I find it exceedingly difficult
to get a liner of only 7 ft. long in one piece, and the majority of 6
ft. liners are fitted _in two pieces_. The joint of the two liners is
rarely _watertight_, and many shafts have been destroyed by this
method of fitting these liners.
I trust that engine builders will make a step further in the fitting
of these liners on these shafts, as it is against the interest of the
_shipowner_ to keep ships in dry dock from such causes as defective
liners, and I think it will be only a matter of time when the screw
shaft will be completely protected from sea water, at least inside the
stern tube; and when this is done, I would have no hesitation in using
steel for screw shafts. Though an easier forging than a crank shaft,
these shafts are often liable to flaws of a very serious character,
owing to the contraction of the _mass_ of metal forming the coupling;
the outside cooling first tears the center open, and when there is not
much metal to turn off the face of the coupling, it is sometimes
undiscovered. Having observed several of these cavities, some only
when the _last cut_ was being taken off, I have considered it
advisable to have holes bored in the end and center of each coupling,
as far through as the thickness of the flange; when the shafts are of
large size, this is sure to find these flaws out. Another flaw, which
has in many cases proved serious when allowed to extend, is situated
immediately abaft the gun metal liner, in front of the propeller.
This may be induced by corrosion, caused by the presence of sea water,
gun metal, and iron, assisted by the rotation of the shaft. It may
also be caused under heavy strain, owing to the over-finishing of the
shaft at this part under the steam hammer.
The forgemen, in these days of competition and low prices, are
instructed to so finish that there won't be much weight to turn off
when completing the shaft in the lathe. This is effected by the use of
half-round blocks under the hammer, at a lower temperature than the
rest of the forging is done, along with the use of a little water
flung on from time to time; and it is remarkable how near a forging is
in truth when centered in the lathe, and how little there is to come
off. The effect of this manipulation is to form a hard ring of close
grain about one inch thick from the circumference of the shaft inward.
The metal in this ring is much harder than that in the rest of the
shaft, and takes all the strain the inner section gives; consequently,
when strain is brought on, either in heavy weather or should the
propeller strike any object at sea or in the Suez canal, a fracture is
caused at the circumference. This, assisted by slight corrosion, has
in my experience led in the course of four months to a screw shaft
being seriously crippled.
I show you a section of a screw shaft found to be flawed, and which I
had broken under the falling weight of a steam hammer, when the
decided difference of the granules near the circumference from that in
the central part conveyed to me that it was weakened by treatment I
have referred to. I think more material should be left on the forging,
and the high finish with a little cold water should be discontinued.
Doing away with the outer bearing in rudder post is an improvement,
provided the bearing in the outer end of screw shaft in the stern tube
is sufficiently large. It allows the rudder post to have its own work
to do without bringing any strain on the screw shaft, and in the event
of the vessel's grounding and striking under the rudder post, it does
not throw any strain on the screw shaft. It also tends to reduce
weight at this part, where all the weight is overhung from the stern
of the vessel.
* * * * *
EXPERIMENTAL AID IN THE DESIGN OF HIGH SPEED STEAMSHIPS.
By D. P.
The achievement of one triumph after another in the matter of high
speed steamships, and especially the confidence with which pledges of
certain results are given and accepted long before actual trials are
made, form one of the most convincing proofs of the important part
which scientific methods play in modern shipbuilding. This is evident
in the case of ships embodying novel or hitherto untried features, and
more especially so in cases where shipbuilders, having no personal
practical experience or data, achieve such results. This was notably
illustrated in the case of the Fairfield Co. undertaking some five
years ago to build and engine a huge craft of most phenomenal form and
proportions, and to propel the vessel at a given speed under
conditions which appeared highly impracticable to many engaged in the
same profession. The contract was proceeded with, however, and the
Czar of Russia's wonderful yacht Livadia was the result, which
(however much she may have justified the professional strictures as to
form and proportions) entirely answered the designer's anticipations
as to speed. Equally remarkable and far more interesting instances are
the Inman liners City of Paris and City of New York, in whose design
there was sufficient novelty to warrant the degree of misgiving which
undoubtedly existed regarding the Messrs. Thomson's ability to attain
the speed required. In the case at least of the City of Paris, Messrs.
Thomson's intrepidity has been triumphantly justified. An instance
still more opposite to our present subject is found in the now
renowned Channel steamers Princess Henrietta and Princess Josephine,
built by Messrs. Denny, of Dumbarton, for the Belgian government. The
speed stipulated for in this case was 20½ knots, and although in one
or two previous Channel steamers, built by the Fairfield Co., a like
speed had been achieved, still the guaranteeing of this speed by
Messrs. Denny was remarkable, in so far as the firm had never
produced, or had to do with, any craft faster than 15 or 16 knots. The
attainment not only of the speed guaranteed, but of the better part of
a knot in excess of that speed, was triumphant testimony to the skill
and care brought to bear upon the undertaking. In this case, at least,
the result was not one due to a previous course of "trial and error"
with actual ships, but was distinctly due to superior practical skill,
backed and enhanced by knowledge and use of specialized branches in
the science of marine architecture. Messrs. Denny are the only firm of
private shipbuilders possessing an experimental tank for recording the
speed and resistance of ships by means of miniature reproductions of
the actual vessels, and to this fact may safely be ascribed their
confidence in guaranteeing, and their success in obtaining, a speed so
remarkable in itself and so much in excess of anything they had
previously had to do with. Confirmatory evidence of their success with
the Belgian steamers is afforded by the fact that they have recently
been instructed to build for service between Stranraer and Larne a
paddle steamer guaranteed to steam 19 knots, and have had inquiries as
to other high speed vessels.
In estimating the power required for vessels of unusual types or of
abnormal speed, where empirical formulæ do not apply, and where data
for previous ships are not available, the system of experimenting with
models is the only trustworthy expedient. In the case of the Czar's
extraordinary yacht, the Livadia, already referred to, it may be
remembered that previous to the work of construction being proceeded
with, experiments were made with a small model of the vessel by the
late Dr. Tideman, at the government tank at Amsterdam. On the strength
of the data so obtained, coupled with the results of trials made with
a miniature of the actual vessel on Loch Lomond, those responsible for
her stipulated speed were satisfied that it could be attained. The
actual results amply justified the reliance placed upon such
experiments.
The design of many of her Majesty's ships has been altered after
trials with their models. This was notably the case in connection with
the design of the Medway class of river gunboats. The Admiralty
constructors at first determined to make them 110 ft. long, by only 26
ft. in breadth. A doubt arising in their minds, the matter was
referred to the late Mr. Froude, who had models made of various
breadths, with which he experimented. The results satisfied the
Admiralty officers that a substantial gain, rather than a loss, would
follow from giving them much greater beam than had been proposed, and
this was amply verified in the actual ships.
So long ago as the last decade of last century, an extended series of
experiments with variously shaped bodies, ships as well as other
shapes, were conducted by Colonel Beaufoy, in Greenland dock, London,
under the auspices of a society instituted to improve naval
architecture at that time. Robert Fulton, of America, David Napier, of
Glasgow, and other pioneers of the steamship, are related to have
carried out systematic model experiments, although of a rude kind in
modern eyes, before entering on some of their ventures. About 1840 Mr.
John Scott Russell carried on, on behalf of the British Association,
of which he was at that time one of its most distinguished members, an
elaborate series of investigations into the form of least resistance
in vessels. For this purpose he leased the Virginia House and grounds,
a former residence of Rodger Stewart, a famous Greenock shipowner of
the early part of the century, the house being used as offices, while
in the grounds an experimental tank was erected. In it tests were made
of the speed and resistance of the various forms which Mr. Russell's
ingenuity evolved--notably those based on the well-known stream line
theory--as possible types of the steam fleets of the future. All the
data derived from experiment was tabulated, or shown graphically in
the form of diagrams, which, doubtless, proved of great interest to
the _savants_ of the British Association of that day. Mr. Russell
returned to London in 1844, and the investigations were discontinued.
It will thus be seen that model experiments had been made by
investigators long before the time of the late Dr. William Froude, of
Torquay. It was not, however, until this gentleman took the subject of
resistance of vessels in hand that designers were enabled to render
the results from model trials accurately applicable to vessels of full
size. This was principally due to his enunciation and verification by
experiment of what is now known as the "law of comparison," or the law
by which one is enabled to refer accurately the resistance of a model
to one of larger size, or to that of a full sized vessel. In effect,
the law is this--for vessels of the same proportional dimensions, or,
as designers say, of the same lines, there are speeds appropriate to
these vessels, which vary as the square roots of the ratio of their
dimensions, and at these appropriate speeds the resistances will vary
as the cubes of these dimensions. The fundament upon which the law is
based has recently been shown to have found expression in the works of
F. Reech, a distinguished French scientist who wrote early in the
century. There are no valid grounds for supposing that the discovery
of Reech was familiar to Froude; but even were this so, it is
abundantly evident that, although never claimed by himself, there are
the best of grounds for claiming the law of comparison, as now
established, to be an independent discovery of Froude's.
Dr. Froude began his investigations with ships' models at the
experimental tank at Torquay about 1872, carrying it on
uninterruptedly until his death in 1879. Since his decease, the work
of investigation has been carried on by his son, Mr. R. E. Froude, who
ably assisted his father, and originated much of the existing
apparatus. At the beginning of 1886, the whole experimental appliances
and effects were removed from Torquay to Haslar, near Portsmouth,
where a large tank and more commodious offices have been constructed,
with a view to entering more extensively upon the work of experimental
investigation. The dimensions of the old tank were 280 ft. in length,
36 ft. in width, and 10 ft. in depth. The new one is about 400 ft.
long, 20 ft. wide, and 9 ft. deep. The new establishment is more
commodious and better equipped than the old, and although the
experiments are taken over a greater length, the operators are enabled
to turn out results with as great dispatch as in the Torquay tank. The
adjacency of the new tank to the dockyard at Portsmouth enables the
Admiralty authorities to make fuller and more frequent use of it than
formerly. Since the value of the work carried on for the British
government has become appreciated, several experimental establishments
of a similar character have been instituted in other countries. The
Dutch government in 1874 formed one at Amsterdam which, up till his
death in 1883, was under the superintendence of Dr. Tideman, whose
labors in this direction were second only to those of the late Dr.
Froude. In 1877 the French naval authorities established an
experimental tank in the dockyard at Brest, and the Italian government
have just completed one on an elaborate scale in the naval dockyard at
Spezia. The Spezia tank, which is 500 ft. in length by about 22 ft. in
breadth, is fully equipped with all the special and highly ingenious
instruments and appliances which the scientific skill of the late Dr.
Froude brought into existence, and have been since his day improved
upon by his son, Mr. R. E. Froude, and other experts.
Through the courtesy of our own Admiralty and of Messrs. Denny, of
Dumbarton, the Italians have been permitted to avail themselves of the
latest improvements which experience has suggested, and the
construction of the special machinery and apparatus required has been
executed by firms in this country having previous experience in this
connection--Messrs. Kelso & Co., of Commerce Street, Glasgow; and Mr.
Robert W. Munro, of London.
Having briefly traced the origin and development of the system of
model experiment, it may now be of interest to describe the _modus
operandi_ of such experiments, and explain the way in which they are
made applicable to actual ships. The models with which experiments are
made in those establishments conducted on the lines instituted by Mr.
Froude are made of paraffin wax, a material well adapted for the
purpose, being easily worked, impervious to water, and yielding a fine
smooth surface. Moreover, when done with, the models may be remelted
for further use and all parings utilized. They are produced in the
following manner: A mould is formed in clay by means of cross sections
made somewhat larger than is actually required, this allowance being
made to admit of the cutting and paring afterward required to bring
the model to the correct point. Into this mould a core is placed,
consisting of a light wooden framework covered with calico and coated
with a thick solution of clay to make it impervious to the melted
paraffin. This latter substance is run into the space between the core
and the mould and allowed to cool. This space, forming the thickness
of the model, is usually from ¾ in. for a model of 10 ft. long to 1¼
in. and 1½ in. for one of 16 ft. and 18 ft. long. When cold, the model
is floated out of the mould by water pressure and placed bottom upward
on the bed of a shaping machine, an ingenious piece of mechanism
devised by the late Dr. Froude, to aid in reducing the rough casting
to the accurate form. The bed of this machine, which travels
automatically while the machine is in operation, can be raised or
lowered to any desired level by adjusting screws. A plan of water
lines of the vessel to be modeled is placed on a tablet geared to the
machine, the travel of which is a function of the travel of the bed
containing the model. With a pointer, which is connected by a system
of levers to the cutting tools, the operator traces out the water
lines upon the plan as the machine and its bed are in motion, with the
result that corresponding lines are cut upon the model. The cutting
tools are swiftly revolving knives which work on vertical spindles
moved in a lateral direction (brought near or removed from each
other), according to the varying breadth of the water lines throughout
the length of the model, as traced out by the operator's pointer. In
this way a series of longitudinal incisions are made on the model at
different levels corresponding to the water lines of the vessel. The
model is now taken from the bed of the machine and the superfluous
material or projection between the incisions is removed by means of a
spokeshave or other sharp hand tool, and the whole surface brought to
the correct form, and made fair and smooth.
To test accuracy of form, the weight of model is carefully taken, and
the displacement at the intended trial draught accurately determined
from the plan of lines. The difference between the weight of model and
the displacement at the draught intended is then put into the bottom
of the model in the form of small bags of shot, and by unique and very
delicately constructed instruments for ascertaining the correct
draught, the smallest error can at once be detected and allowed for.
The models vary in size from about one-tenth to one-thirtieth of the
size of the actual ship. A model of the largest size can be produced
and its resistance determined at a number of speeds in about two days
or so. The mode of procedure in arranging the model for the resistance
experiment, after the model is afloat in the tank at the correct
draught and trim, consists in attaching to it a skillfully devised
dynamometric apparatus secured to a lightly constructed carriage. This
carriage traverses a railway which extends the whole length of the
tank about 15 in. or 18 in. above the water. The floating model is
carefully guided in its passage through the water by a delicate
device, keeping it from deviating either to the right or left, but at
the same time allowing a free vertical and horizontal motion. The
carriage with the model attached is propelled by means of an endless
steel wire rope, passing at each end of the tank around a drum, driven
by a small stationary engine, fitted with a very sensitive governor,
capable of being so adjusted that any required speed may be given to
the carriage and model. The resistance which the model encounters in
its passage through the water is communicated to a spiral spring, and
the extension this spring undergoes is a measure of the model's
resistance. The amount of the extension is recorded on a revolving
cylinder to a much enlarged scale through the medium of levers or bell
cranks supported by steel knife edges resting on rocking pieces. On
the same cylinder are registered "time" and "distance" diagrams, by
means of which a correct measure of the speed is obtained. The time
diagram is recorded by means of a clock attached to an electric
circuit, making contact every half second, and actuating a pen which
forms an indent in what would otherwise be a straight line on the
paper. The distance pen, by a similar arrangement, traces another line
on the cylinder in which are indents corresponding to fixed distances
of travel along the tank, the indents being caused by small
projections which strike a trigger at the bottom of the carriage as it
passes, and make electric contact. From these time and distance
diagrams accurate account can be taken of the speed at which the model
and its supporting carriage have been driven. Thus on the same
cylinder is recorded graphically the speed and resistance of the
model. The carriage may be driven at any assigned speed by adjusting
the governor of the driving engine already alluded to, but the record
of the speed by means of the time and distance diagrams is more
definite. When the resistances of the model have been obtained at
several speeds, varying in some cases from 50 to 1,000 feet per
minute, the speeds are set off in suitable units along a base line,
and for every speed at which resistance is measured, the resistance is
set off to scale as an ordinate value at those speeds. A line passing
through these spots forms the "curve of resistance," from which the
resistance experienced by the model at the given trial speeds or any
intermediate speed can be ascertained. The resistance being known, the
power required to overcome resistance and drive the actual ship at any
given speed is easily deduced by applying the rule before described as
the law of comparison.--_The Steamship._
* * * * *
THE SHIP IN THE NEW FRENCH BALLET OF THE "TEMPEST."
A new ballet, entitled the "Tempest," by Messrs. Barbier and Thomas,
has recently been put upon the stage of the Opera at Paris with superb
settings. One of the most important of the several tableaux exhibited
is the last one of the third act, in which appears a vessel of unusual
dimensions for the stage, and which leaves far behind it the
celebrated ships of the "Corsaire" and "L'Africaine." This vessel,
starting from the back of the stage, advances majestically, describes
a wide circle, and stops in front of the prompter's box.
[Illustration: FIG. 1.--SHIP OF THE "TEMPEST," IN PROCESS OF
CONSTRUCTION.]
[Illustration: FIG. 2.--SETTING OF THE SCENERY BEFORE AND AFTER THE
APPEARANCE OF THE SHIP.]
As the structure of this vessel and the mechanism by which it is moved
are a little out of the ordinary, we shall give some details in regard
to them. First, the sea is represented by four parallel strips of
water, each formed of a vertical wooden frame entirely free in its
movements (Fig. 2). The ship (Figs. 1, 2, 3, 4 and 5) is carried by
wheels that roll over the floor of the stage. It is guided in its
motion by two grooved bronze wheels and by a rail formed of a simple
reversed T-iron which is fixed to the floor by bolts. In measure as it
advances, the strips of water open in the center to allow it to pass,
and, as the vessel itself is covered up to the water line with painted
canvas imitating the sea, it has the appearance of cleaving the waves.
As soon as it has passed, the three strips of water in the rear rise
slightly. When the vessel reaches the first of the strips, the three
other strips, at first juxtaposed against the preceding, spread out
and thus increase the extent of the sea, while the inclined plane of
the preceding tableau advances in order to make place for the vessel.
The shifting of this inclined place is effected by simply pulling upon
the carpet that covers it, and which enters a groove in the floor in
front of the prompter's box. At this moment, the entire stage seems to
be in motion, and the effect is very striking.
[Illustration: FIG. 3.--SHIP OF THE NEW BALLET, THE "TEMPEST."]
We come now to the details of construction of the vessel. It is not
here a question of a ship represented simply by means of frames and
accessories, but of a true ship in its entirety, performing its
evolutions over the whole stage. Now, a ship is not constructed at a
theater as in reality. It does not suffice to have it all entire upon
the stage, but it is necessary also to be able to dismount it after
every representation, and that, too, in a large number of pieces that
can be easily stored away. Thus, the vessel of the Tempest, which
measures a dozen yards from stem to stern, and is capable of carrying
fifty persons, comes apart in about 250 pieces of wood, without
counting all the iron work, bolts, etc. Nevertheless, it can be
mounted in less than two hours by ten skilled men.
[Illustration: FIG. 4.--THE SHIP WITH ITS OCCUPANTS.]
The visible hull of the ship is placed upon a large and very strong
wooden framework, formed of twenty-six trusses. In the center, there
are two longitudinal trusses about three feet in height by twenty-five
in length, upon which are assembled, perpendicularly, seven other
trusses. In the interior there are six transverse pieces held by
stirrup bolts, and at the extremity of each of these is fixed a
thirteen-inch iron wheel. It is upon these twelve wheels that the
entire structure rolls.
There are in addition the two bronze guide wheels that we have already
spoken of. In the rear there are two large vertical trusses sixteen
feet in height, which are joined by ties and descend to the bottom of
the frame, to which they are bolted. These are worked out into steps
and constitute the skeleton of the immense stern of the vessel. The
skeleton of the prow is formed of a large vertical truss which is
bolted to the front of the frame and is held within by a tie bar. On
each side of this truss are placed the _parallels_ (Figs. 1 and 3),
which are formed of pieces of wood that are set into the frame below
and are provided above with grooves for the passage of iron rods that
support the foot rests by means of which the supernumeraries are
lifted. As a whole, those rods constitute a jointed parallelogram, so
that the foot rest always remains horizontal while describing a curve
of five feet radius from the top of the frame to the deck of the
vessel. They are actuated by a cable which winds around a small
windlass fixed in the interior of the frame.
[Illustration: FIG. 5.--THE SHIP AS SEEN FROM THE STAGE.]
The large mast consists of a vertical sheath 10 ft. high, which is set
into the center of the frame, and in the interior of which slides a
wooden spar that exceeds it by 5 ft. at first, and is capable of being
drawn out as many more feet for the final apotheosis. This part of the
mast carries three footboards and a platform for the reception of
"supers." It is actuated by a windlass placed upon the frame.
To form the skeleton of the vessel there are mounted upon the frame a
series of eight large vertical trusses parallel with each other and
cross-braced by small trusses. The upper part of these supports the
flooring of the deck, and their exterior portion affects the curve of
a ship's sides. It is to these trusses that are attached the panels
covered with painted canvas that represent the hull. These panels are
nine in number on each side. Above are placed those that simulate the
nettings and those that cover the prow or form its crest.
The turret that surrounds the large mast is formed of vertical trusses
provided with panels of painted canvas and carrying a floor for the
figurants to stand upon.
The bowsprit is in two parts, one sliding in the other. The front
portion is at first pulled back, in order to hide the vessel entirely
in the side scenes. It begins to make its appearance before the vessel
itself gets under way. Light silken cordages connect the mast, the
bowsprit, and the small mast at the stern.
On each side of the vessel, there are bolted to the frame that
supports it five iron frames covered with canvas (Fig. 3), which reach
the level of the water line, and upon which stand the "supers"
representing the naiads that are supposed to draw the ship upon the
beach. Finally at the bow there is fixed a frame which supports a
danseuse representing the living prow of the vessel.
The vessel is drawn to the middle of the stage by a cable attached to
its right side and passing around a windlass placed in the side scenes
to the left (Fig. 2). It is at the same time pushed by machinists
placed in the interior of the framework. The latter, as above stated,
is entirely covered with painted canvas resembling water.
As the vessel, freighted with harmoniously grouped spirits, and with
naiads, sea fairies, and graceful genii seeming to swim around it,
sails in upon the stage, puts about, and advances as if carried along
by the waves to the front of the stage, the effect is really
beautiful, and does great credit to the machinists of the Opera.
We are indebted to _Le Genie Civil_ and _Le Monde Illustré_ for the
description and engravings.
* * * * *
THE GIRARD HYDRAULIC RAILWAY.
[Illustration: FIG. 1.]
[Illustration: FIG. 2.]
We give herewith some illustrations of this railway which has recently
excited so much technical interest in Europe and America, and which
threatens to revolutionize both the method and velocity of traveling,
if only the initial expense of laying the line can be brought within
moderate limits. A short line of railway has been laid in Paris, and
we have there examined it, and traveled over the line more than once;
so that we can testify to the smoothness and ease of the motion. Sir
Edward Watkin examined the railway recently, and we understand that a
line two miles long is to be laid in London, under his auspices. He
seems to think it might be used for the Channel tunnel, being both
smokeless and noiseless. It might also, if it could be laid at a
sufficiently low price, be useful for the underground railways in
London, of one of which he is chairman. We are favorably impressed by
the experiments we have witnessed; our misgivings are as to the cost.
The railway is the invention of the well known hydraulic engineer,
Monsieur Girard, who, as early as 1852, endeavored to replace the
ordinary steam traction on railways by hydraulic propulsion, and in
1854 sought to diminish the resistance to the movement of the wagons
by removing the wheels, and causing them to slide on broad rails. In
order to test the invention, Mons. Girard demanded, and at the end of
1869 obtained, a concession for a short line from Paris to Argenteuil,
starting in front of the Palais de l'Industrie, passing by Le Champ de
Courses de Longchamps, and crossing the Seine at Suresnes.
Unfortunately, the war of 1870-71 intervened, during which the works
were destroyed and Mons. Girard was killed. After his death the
invention was neglected for some years. A short time ago, however, one
of his former colleagues, Mons. Barre, purchased the plans and
drawings of Mons. Girard from his family, and having developed the
invention, and taken out new patents, formed a company to work them.
The invention may be divided into two parts, which are distinct, the
first relating to the mode of supporting the carriages and the second
to their propulsion. Each carriage is carried by four or six shoes,
shown in Figs. 3, 4, and 5; and these shoes slide on a broad, flat
rail, 8 in. or 10 in. wide. The rail and shoe are shown in section in
Fig. 1. The rail is bolted to longitudinal wooden sleepers, and the
shoe is held on the rail by four pieces of metal, A, two on each side,
which project slightly below the top of the rail. The bottom of the
shoe which is in contact with the rail is grooved or channeled, so as
to hold the water and keep a film between each shoe and the rail. The
carriage is supported by vertical rods, which fit one into each shoe,
a hole being formed for that purpose; and the point of support being
very low, and quite close to the rail, great stability is insured. It
is proposed to make the rail of the form shown in Fig. 2 in future, as
this will avoid the plates, A, and the flanges, B, will help to keep
the water on the rail. Figs. 3, 4, and 5 show the shoe in detail. Fig.
3 gives a longitudinal section, Fig. 4 is a plan, and Fig. 5 is a plan
of the shoe inverted, showing the grooves in its face. Fig. 3 shows
the hollow shoe, into which water at a pressure of ten atmospheres is
forced by a pipe from a tank on the tender. The water enters by the
pipe, C, and fills the whole of the chamber, D. The water attempts to
escape, and in doing so lifts the shoe slightly, thus filling the
first groove of the chamber. The pressure again lifts the shoe, and
the second chamber is filled; and so on, until ultimately the water
escapes at the ends, E, and sides, F. Thus a film of water is kept
between the shoe and the rail, and on this film the carriage is said
to float. The water runs away into the channels, H H (Fig. 6), and is
collected to be used over again. Fig. 3 also shows the means of
supporting the carriage on the shoe by means of K, the point of
support being very low. The system of grooves on the lower face of the
shoe is shown in Fig. 5. So much for the means by which wheels are
dispensed with, and the carriage enabled to slide along the line.
[Illustration: FIG. 3.]
[Illustration: FIG. 4.]
[Illustration: FIG. 5.]
[Illustration: FIG. 6.]
The next point is the method of propulsion. Figs. 7 and 8 give an
elevation and plan of one of the experimental carriages. Along the
under side of each of the carriages a straight turbine, L L, extends
the whole length, and water at high pressure impinges on the blades of
this turbine from a jet, M, and by this means the carriage is moved
along. A parabolic guide, which can be moved in and out of gear by a
lever, is placed under the tender, and this on passing strikes the
tappet, S, and opens the valve which discharges the water from the
jet, M, and this process is repeated every few yards along the whole
line. The jets, M, must be placed at such a distance apart that at
least one will be able to operate on the shortest train that can be
used. In this turbine there are two sets of blades, one above the
other, placed with their concave sides in opposite directions, so that
one set is used for propelling in one direction and the other in the
opposite direction. In Fig. 6 it is seen that the jet, M, for one
direction is just high enough to act against the blades, Q, while the
other jet is higher, and acts on the blades, P, for propulsion in the
opposite direction. The valves, R, which are opened by the tappet, S,
are of peculiar construction, and we hope soon to be able to give
details of them. Reservoirs (Fig. 6) holding water at high pressure
must be placed at intervals, and the pipe, T, carrying high pressure
water must run the whole length of the line. Fig. 6 shows a cross
section of the rail and carriage, and gives a good idea of the general
arrangements. The absence of wheels and of greasing and lubricating
arrangements will alone effect a very great saving, as we are informed
that on the Lyons Railway, which is 800 kilometers long, the cost of
oil and grease exceeds £400,000 per annum. As Sir Edward Watkin
recently explained, all the great railway companies have long tried to
find a substitute for wheels, and this railway appears to offer a
solution of that problem. Mons. Barre thinks that a speed of 200
kilometers (or 120 miles) per hour may be easily and safely attained.
[Illustration: FIG. 7.]
[Illustration: FIG. 8.]
Of course, as there is no heavy locomotive, and as the traction does
not depend upon pressure on the rail, the road may be made
comparatively light. The force required to move a wagon along the road
is very small, Mons. Barre stating, as the result of his experiments,
that an effort amounting to less than half a kilogramme is sufficient
to move one ton when suspended on a film of water with his improved
shoes. It is recommended that the stations be placed at the summit of
a double incline, so that on going up one side of the incline the
motion of the train may be arrested, and on starting it may be
assisted. No brakes are required, as the friction of the shoe against
the rail, when the water under pressure is not being forced through, is
found to be quite sufficient to bring the train to a standstill in a
very short distance. The same water is run into troughs by the side of
the line, and can be used over and over again indefinitely, and in the
case of long journeys, the water required for the tender could be taken
up while the train is running. The principal advantages claimed for
the railway are: The absence of vibration and of side rolling motion;
the pleasure of traveling is comparable to that of sleighing over a
surface of ice, there is no noise, and what is important in town
railways, no smoke; no dust is caused by the motion of the train during
the journey. It is not easy for the carriages to be thrown from the
rails, since any body getting on the rail is easily thrown off by the
shoe, and will not be liable to get underneath, as is the case with
wheels; the train can be stopped almost instantly, very smoothly, and
without shock. Very high speed can be attained; with water at a
pressure of 10 kilogrammes, a speed of 140 kilometers per hour can be
attained; great facility in climbing up inclines and turning round the
curves; as fixed engines are employed to obtain the pressure, there is
great economy in the use of coal and construction of boilers, and
there is a total absence of the expense of lubrication. It is,
however, difficult to see how the railway is to work during a long and
severe frost. We hope to give further illustrations at an early date
of this remarkable invention.--_Industries._
* * * * *
QUARTZ FIBERS.[1]
[Footnote 1: Lecture delivered at the Royal Institution, on
Friday, June 14, by Mr. C. V. Boys, F.R.S.--_Nature._]
In almost all investigations which the physicist carries out in the
laboratory, he has to deal with and to measure with accuracy those
subtile and to our senses inappreciable forces to which the so-called
laws of nature give rise. Whether he is observing by an electrometer
the behavior of electricity at rest or by a galvanometer the action of
electricity in motion, whether in the tube of Crookes he is
investigating the power of radiant matter, or with the famous
experiment of Cavendish he is finding the mass of the earth--in these
and in a host of other cases he is bound to measure with certainty and
accuracy forces so small that in no ordinary way could their existence
be detected, while disturbing causes which might seem to be of no
particular consequence must be eliminated if his experiments are to
have any value. It is not too much to say that the very existence of
the physicist depends upon the power which he possesses of producing
at will and by artificial means forces against which he balances those
that he wishes to measure.
I had better perhaps at once indicate in a general way the magnitude
of the forces with which we have to deal.
The weight of a single grain is not to our senses appreciable, while
the weight of a ton is sufficient to crush the life out of any one in
a moment. A ton is about 15,000,000 grains. It is quite possible to
measure with unfailing accuracy forces which bear the same relation to
the weight of a grain that a grain bears to a ton.
To show how the torsion of wires or threads is made use of in
measuring forces, I have arranged what I can hardly dignify by the
name of an experiment. It is simply a straw hung horizontally by a
piece of wire. Resting on the straw is a fragment of sheet iron
weighing ten grains. A magnet so weak that it cannot lift the iron yet
is able to pull the straw round through an angle so great that the
existence of the feeble attraction is evident to every one in the
room.
Now it is clear that if, instead of a straw moving over the table
simply, we had here an arm in a glass case and a mirror to read the
motion of the arm, it would be easy to observe a movement a hundred or
a thousand times less than that just produced, and therefore to
measure a force a hundred or a thousand times less than that exerted
by this feeble magnet.
Again, if instead of wire as thick as an ordinary pin I had used the
finest wire that can be obtained, it would have opposed the movement
of the straw with a far less force. It is possible to obtain wire ten
times finer than this stubborn material, but wire ten times finer is
much more than ten times more easily twisted. It is ten thousand times
more easily twisted. This is because the torsion varies as the fourth
power of the diameter. So we say 10 × 10 = 100, 100 × 100 = 10,000.
Therefore, with the finest wire, forces 10,000 times feebler still
could be observed.
It is therefore evident how great is the advantage of reducing the
size of a torsion wire. Even if it is only halved, the torsion is
reduced sixteenfold. To give a better idea of the actual sizes of such
wires and fibers as are in use, I shall show upon the screen a series
of such photographs taken by Mr. Chapman, on each of which a scale of
thousandths of an inch has been printed.
[Illustration: Scale of 1000ths of an inch for Figs. 1 to 7. The scale
of Figs. 8 and 9 is much finer.]
[Illustration: FIG. 1.]
[Illustration: FIG. 2.]
[Illustration: FIG. 3.]
The first photograph (Fig. 1) is an ordinary hair--a sufficiently
familiar object, and one that is generally spoken of as if it were
rather fine. Much finer than this is the specimen of copper wire now
on the screen (Fig. 2), which I recently obtained from Messrs. Nalder
Brothers. It is only a little over one-thousandth of an inch in
diameter. Ordinary spun glass, a most beautiful material, is about
one-thousandth of an inch in diameter, and this would appear to be an
ideal torsion thread (Fig. 3). Owing to its fineness, its torsion
would be extremely small, and the more so because glass is more easily
deformed than metals. Owing to its very great strength, it can carry
heavier loads than would be expected of it. I imagine many physicists
must have turned to this material in their endeavor to find a really
delicate torsion thread. I have so turned only to be disappointed. It
has every good quality but one, and that is its imperfect elasticity.
For instance, a mirror hung by a piece of spun glass is casting an
image of a spot of light on the scale. If I turn the mirror, by means
of a fork, twice to the right, and then turn it back again, the light
does not come back to its old point of rest, but oscillates about a
point on one side, which, however, is slowly changing, so that it is
impossible to say what the point of rest really is. Further, if the
glass is twisted one way first and then the other way, the point of
rest moves in a manner which shows that it is not influenced by the
last deflection alone: the glass remembers what was done to it
previously. For this reason spun glass is quite unsuitable as a
torsion thread; it is impossible to say what the twist is at any time,
and therefore what is the force developed.
[Illustration: FIG. 4.]
So great has the difficulty been in finding a fine torsion thread that
the attempt has been given up, and in all the most exact instruments
silk has been used. The natural cocoon fibers, as shown on the screen
(Fig. 4), consist of two irregular lines gummed together, each about
one two-thousandth of an inch in diameter. These fibers must be
separated from one another and washed. Then each component will,
according to the experiment of Gray, carry nearly 60 grains before
breaking, and can be safely loaded with 15 grains. Silk is therefore
very strong, carrying at the rate of from 10 to 20 tons to the square
inch. It is further valuable in that its torsion is far less than that
of a fiber of the same size of metal or even of glass, if such could
be produced. The torsion of silk, though exceedingly small, is quite
sufficient to upset the working of any delicate instrument, because it
is never constant. At one time the fiber twists one way and another
time in another, and the evil effect can only be mitigated by using
large apparatus in which strong forces are developed. Any attempt that
may be made to increase the delicacy of apparatus by reducing their
dimensions is at once prevented by the relatively great importance of
the vagaries of the silk suspension.
The result, then, is this. The smallness, the length of period, and
therefore delicacy, of the instruments at the physicist's disposal
have until lately been simply limited by the behavior of silk. A more
perfect suspension means still more perfect instruments, and therefore
advance in knowledge.
It was in this way that some improvements that I was making in an
instrument for measuring radiant heat came to a deadlock about two
years ago. I would not use silk, and I could not find anything else
that would do. Spun glass, even, was far too coarse for my purpose, it
was a thousand times too stiff.
[Illustration: FIG. 5.]
There is a material invented by Wollaston long ago, which, however, I
did not try because it is so easily broken. It is platinum wire which
has been drawn in silver, and finally separated by the action of
nitric acid. A specimen about the size of a single line of silk is now
on the screen, showing the silver coating at one end (Fig. 5).
As nothing that I knew of could be obtained that would be of use to
me, I was driven to the necessity of trying by experiment to find some
new material. The result of these experiments was the development of a
process of almost ridiculous simplicity which it may be of interest
for me to show.
The apparatus consists of a small crossbow, and an arrow made of straw
with a needle point. To the tail of the arrow is attached a fine rod
of quartz which has been melted and drawn out in the oxyhydrogen jet.
I have a piece of the same material in my hand, and now after melting
their ends and joining them together, an operation which produces a
beautiful and dazzling light, all I have to do is to liberate the
string of the bow by pulling the trigger with one foot, and then if
all is well a fiber will have been drawn by the arrow, the existence
of which can be made evident by fastening to it a piece of stamp
paper.
In this way threads can be produced of great length, of almost any
degree of fineness, of extraordinary uniformity, and of enormous
strength. I do not believe, if any experimentalist had been promised
by a good fairy that he might have anything he desired, that he would
have ventured to ask for any one thing with so many valuable
properties as these fibers possess. I hope in the course of this
evening to show that I am not exaggerating their merits.
[Illustration: FIG. 6.]
[Illustration: FIG. 7.]
In the first place, let me say something about the degree of fineness
to which they can be drawn. There is now projected upon the screen a
quartz fiber one five-thousandth of an inch in diameter (Fig. 6). This
is one which I had in constant use in an instrument loaded with about
30 grains. It has a section only one-sixth of that of a single line of
silk, and it is just as strong. Not being organic, it is in no way
affected by changes of moisture and temperature, and so it is free
from the vagaries of silk which give so much trouble. The piece used
in the instrument was about 16 inches long. Had it been necessary to
employ spun glass, which hitherto was the finest torsion material,
then, instead of 16 inches, I should have required a piece 1,000 feet
long, and an instrument as high as the Eiffel tower to put it in.
There is no difficulty in obtaining pieces as fine as this yards long
if required, or in spinning it very much finer. There is upon the
screen a single line made by the small garden spider, and the size of
this is perfectly evident (Fig. 7). You now see a quartz fiber far
finer than this, or, rather, you see a diffraction phenomenon, for no
true image is formed at all; but even this is a conspicuous object in
comparison with the tapering ends, which it is absolutely impossible
to trace in a microscope. The next two photographs, taken by Mr.
Nelson, whose skill and resources are so famous, represent the extreme
end of a tail of quartz, and, though the scale is a great deal larger
than that used in the other photographs, the end will be visible only
to a few. Mr. Nelson has photographed here what it is absolutely
impossible to see. What the size of these ends may be, I have no means
of telling. Dr. Royston Piggott has estimated some of them at less
than one-millionth of an inch, but, whatever they are, they supply for
the first time objects of extreme smallness the form of which is
certainly known, and, therefore, I cannot help looking upon them as
more satisfactory tests for the microscope than diatoms and other
things of the real shape of which we know nothing whatever.
Since figures as large as a million cannot be realized properly, it
may be worth while to give an illustration of what is meant by a fiber
one-millionth of an inch in diameter.
A piece of quartz an inch long and an inch in diameter would, if drawn
out to this degree of fineness, be sufficient to go all the way round
the world 658 times; or a grain of sand just visible--that is,
one-hundredth of an inch long and one hundredth of an inch in
diameter--would make one thousand miles of such thread. Further, the
pressure inside such a thread due to a surface tension equal to that
of water would be 60 atmospheres.
Going back to such threads as can be used in instruments, I have made
use of fibers one ten-thousandth of an inch in diameter, and in these
the torsion is 10,000 times less than that of spun glass.
As these fibers are made finer their strength increases in proportion
to their size, and surpasses that of ordinary bar steel, reaching, to
use the language of engineers, as high a figure as 80 tons to the
inch. Fibers of ordinary size have a strength of 50 tons to the inch.
While it is evident that these fibers give us the means of producing
an exceedingly small torsion, and one that is not affected by weather,
it is not yet evident that they may not show the same fatigue that
makes spun glass useless. I have, therefore, a duplicate apparatus
with a quartz fiber, and you will see that the spot of light comes
back to its true place on the screen after the mirror has been twisted
round twice.
I shall now for a moment draw your attention to that peculiar property
of melted quartz that makes threads such as I have been describing a
possibility. A liquid cylinder, as Plateau has so beautifully shown,
is an unstable form. It can no more exist than can a pencil stand on
its point. It immediately breaks up into a series of spheres. This is
well illustrated in that very ancient experiment of shooting threads
of resin electrically. When the resin is hot, the liquid cylinders,
which are projected in all directions, break up into spheres, as you
see now upon the screen. As the resin cools, they begin to develop
tails; and when it is cool enough, i.e., sufficiently viscous, the
tails thicken and the beads become less, and at last uniform threads
are the result. The series of photographs show this well.
[Illustration: FIG. 8.]
[Illustration: FIG. 9.]
There is a far more perfect illustration which we have only to go into
the garden to find. There we may see in abundance what is now upon the
screen--the webs of those beautiful geometrical spiders. The radial
threads are smooth like the one you saw a few minutes ago, but the
threads that go round and round are beaded. The spider draws these
webs slowly, and at the same time pours upon them a liquid, and still
further to obtain the effect of launching a liquid cylinder in space
he, or rather she, pulls it out like the string of a bow, and lets it
go with a jerk. The liquid cylinder cannot exist, and the result is
what you now see upon the screen (Fig. 8). A more perfect illustration
of the regular breaking up of a liquid cylinder it would be impossible
to find. The beads are, as Plateau showed they ought to be,
alternately large and small, and their regularity is marvelous.
Sometimes two still smaller beads are developed, as may be seen in the
second photograph, thus completely agreeing with the results of
Plateau's investigations.
I have heard it maintained that the spider goes round her web and
places these beads there afterward. But since a web with about 360,000
beads is completed in an hour--that is at the rate of about 100 a
second--this does not seem likely. That what I have said is true, is
made more probable by the photograph of a beaded web that I have made
myself by simply stroking a quartz fiber with a straw wetted with
castor oil (Fig. 9); it is rather larger than a spider line; but I
have made beaded threads, using a fine fiber, quite indistinguishable
from a real spider web, and they have the further similarity that they
are just as good for catching flies.
Now, going back to the melted quartz, it is evident that if it ever
became perfectly liquid, it could not exist as a fiber for an instant.
It is the extreme viscosity of quartz, at the heat even of an electric
arc, that makes these fibers possible. The only difference between
quartz in the oxyhydrogen jet and quartz in the arc is that in the
first you make threads and in the second are blown bubbles. I have in
my hand some microscopic bubbles of quartz showing all the perfection
of form and color that we are familiar with in the soap bubble.
An invaluable property of quartz is its power of insulating perfectly,
even in an atmosphere saturated with water. The gold leaves now
diverging were charged some time before the lecture, and hardly show
any change, yet the insulator is a rod of quartz only three-quarters
of an inch long, and the air is kept moist by a dish of water. The
quartz may even be dipped in the water and replaced with the water
upon it without any difference in the insulation being observed.
Not only can fibers be made of extreme fineness, but they are
wonderfully uniform in diameter. So uniform are they that they
perfectly stand an optical test so severe that irregularities
invisible in any microscope would immediately be made apparent. Every
one must have noticed when the sun is shining upon a border of flowers
and shrubs how the lines which spiders use as railways to travel from
place to place glisten with brilliant colors. These colors are only
produced when the fibers are sufficiently fine. If you take one of
these webs and examine it in the sunlight, you will find that the
colors are variegated, and the effect, consequently, is one of great
beauty.
A quartz fiber of about the same size shows colors in the same way,
but the tint is perfectly uniform on the fiber. If the color of the
fiber is examined with a prism, the spectrum is found to consist of
alternate bright and dark bands. Upon the screen are photographs
taken by Mr. Briscoe, a student in the laboratory at South Kensington,
of the spectra of some of these fibers at different angles of
incidence. It will be seen that coarse fibers have more bands than
fine, and that the number increases with the angle of incidence of the
light. There are peculiarities in the march of the bands as the angle
increases which I cannot describe now. I may only say that they appear
to move not uniformly, but in waves, presenting very much the
appearance of a caterpillar walking.
So uniform are the quartz fibers that the spectrum from end to end
consists of parallel bands. Occasionally a fiber is found which
presents a slight irregularity here and there. A spider line is so
irregular that these bands are hardly observable; but, as the
photograph on the screen shows, it is possible to trace them running
up and down the spectrum when you know what to look for.
To show that these longitudinal bands are due to the irregularities, I
have drawn a taper piece of quartz by hand, in which the two edges
make with one another an almost imperceptible angle, and the spectrum
of this shows the gradual change of diameter by the very steep angle
at which the bands run up the spectrum.
Into the theory of the development of these bands I am unable to
enter; that is a subject on which your professor of natural philosophy
is best able to speak. Perhaps I may venture to express the hope, as
the experimental investigation of this subject is now rendered
possible, that he may be induced to carry out a research for which he
is so eminently fitted.
Though this is a subject which is altogether beyond me, I have been
able to use the results in a practical way. When it is required to
place into an instrument a fiber of any particular size, all that has
to be done is to hold the frame of fibers toward a bright and distant
light, and look at them through a low-angled prism. The banded spectra
are then visible, and it is the work of a moment to pick out one with
the number of bands that has been found to be given by a fiber of the
desired size. A coarse fiber may have a dozen or more, while such
fibers as I find most useful have only two dark bands. Much finer ones
exist, showing the colors of the first order with one dark band; and
fibers so fine as to correspond to the white or even the gray of
Newton's scale are easily produced.
Passing now from the most scientific test of the uniformity of these
fibers, I shall next refer to one more homely. It is simply this: The
common garden spider, except when very young, cannot climb up one of
the same size as the web on which she displays such activity. She is
perfectly helpless, and slips down with a run. After vainly trying to
make any headway, she finally puts her hands (or feet) into her mouth
and then tries again, with no better success. I may mention that a
male of the same species is able to run up one of these with the
greatest ease, a feat which may perhaps save the lives of a few of
these unprotected creatures when quartz fibers are more common.
It is possible to make any quantity of very fine quartz fiber without
a bow and arrow at all, by simply drawing out a rod of quartz over and
over again in a strong oxyhydrogen jet. Then, if a stand of any sort
has been placed a few feet in front of the jet, it will be found
covered with a maze of thread, of which the photograph on the screen
represents a sample. This is hardly distinguishable from the web spun
by this magnificent spider in corners of greenhouses and such places.
By regulating the jet and the manipulation, anything from one of these
stranded cables to a single ultro-microscope line may be developed.
And now that I have explained that these fibers have such valuable
properties, it will no doubt be expected that I should perform some
feat with their aid which, up to the present time, has been considered
impossible, and this I intend to do.
Of all experiments, the one which has most excited my admiration is
the famous experiment of Cavendish, of which I have a full size model
before you. The object of this experiment is to weigh the earth by
comparing directly the force with which it attracts things with that
due to large masses of lead. As is shown by the model, any attraction
which these large balls exert on the small ones will tend to deflect
this 6 ft. beam in one direction, and then if the balls are reversed
in position, the deflection will be in the other direction. Now, when
it is considered how enormously greater the earth is than these balls,
it will be evident that the attraction due to them must be in
comparison excessively small. To make this evident, the enormous
apparatus you see had to be constructed, and then, using a fine
torsion wire, a perfectly certain but small effect was produced. The
experiment, however, could only be successfully carried out in cellars
and underground places, because changes of temperature produced
effects greater than those due to gravity.[2]
[Footnote 2: Dr. Lodge has been able, by an elaborate
arrangement of screens, to make this attraction just evident to
an audience.--C. V. B.]
Now I have in a hole in the wall an instrument no bigger than a
galvanometer, of which a model is on the table. The balls of the
Cavendish apparatus, weighing several hundredweight each, are replaced
by balls weighing 1¾ pounds only. The smaller balls of 1¾ pounds are
replaced by little weights of 15 grains each. The 6 foot beam is
replaced by one that will swing round freely in a tube three-quarters
of an inch in diameter. The beam is, of course, suspended by a quartz
fiber. With this microscopic apparatus, not only is the very feeble
attraction observable, but I can actually obtain an effect eighteen
times as great as that given by the apparatus of Cavendish, and what
is more important, the accuracy of observation is enormously
increased.
The light from a lamp passes through a telescope lens, and falls on
the mirror of the instrument. It is reflected back to the table, and
thence by a fixed mirror to the scale on the wall, where it comes to a
focus. If the mirror on the table were plane, the whole movement of
the light would be only about eight inches, but the mirror is convex,
and this magnifies the motion nearly eight times. At the present
moment the attracting weights are in one extreme position, and the
line of light is quiet. I will now move them to the other position,
and you will see the result--the light slowly begins to move, and
slowly increases in movement. In forty seconds it will have acquired
its highest velocity, and in forty more it will have stopped at 5
feet 8½ inches from the starting point, after which it will slowly
move back again, oscillating about its new position of rest.
It is not possible at this hour to enter into any calculations; I will
only say that the motion you have seen is the effect of a force of
less than one ten-millionth of the weight of a grain, and that with
this apparatus I can detect a force two thousand times smaller still.
There would be no difficulty even in showing the attraction between
two No. 5 shot.
And now, in conclusion, I would only say that if there is anything
that is good in the experiments to which I have this evening directed
your attention, experiments conducted largely with sticks, and string,
and straw and sealing wax, I may perhaps be pardoned if I express my
conviction that in these days we are too apt to depart from the simple
ways of our fathers, and instead of following them, to fall down and
worship the brazen image which the instrument maker hath set up.
* * * * *
NATURE, COMPOSITION, AND TREATMENT OF ANIMAL AND VEGETABLE FABRICS.
The inseparable duties of studying the composition of the various
animal and vegetable fabrics, as also their nature--when in contact
with the various mineral, vegetable, animal, and gaseous bodies
applied in the individual industries--should not devolve upon the
heads, chemists, or managers of firms alone. It is most important that
every intelligent workman, whom we cannot expect to acquire a very
extensive knowledge of chemistry and perfect acquaintance of the
particular nature and component parts of fabrics, should, at least, be
able to thwart the possibility of the majority of accidents brought
about in regard to the quality and aspect of materials treated by
them.
In the treatment of wool the first operations are of no mean
importance, and the whole subsequent operations and final results,
almost as a whole, depend on the manner in which the fleece washing
had been effected. In presence of suintine, as also fatty matters, as
well as the countless kinds of acids deposited on the wool through
exudation from the body, etc., the various agents and materials cannot
act and deposit as evenly as might be desired, and the complete
obliteration of the former, therefore, becomes an absolute necessity.
For vegetable fabrics a great technical and practical knowledge is
already requisite in their cultivation itself, and before any
operations are necessary at all. One of the greatest points is the
ripeness of the fibers. It is almost an impossibility to produce
delicate colors on vegetable fabrics which were gathered
inopportunely. Numerous experiments have been made on cotton
containing smaller or larger quantities of unripe fibers, and after
the necessary preceding operations, have been dyed in rose, purple,
and blue colors, and the beauty of the shades invariably differed in
proportion to the greater or lesser quantities of unripe fibers
contained in the samples, and by a careless admixture of unripe and
unseasoned fibers the most brilliant colors have been completely
spoiled in the presence of the former. These deficiencies of unripe
vegetable fibers are so serious that the utmost precautions should be
taken, not only by planters to gather the fibers in a ripe state, but
the natural aspect of ripe and unripe fibers and their respective
differences should be known to the operators of the individual
branches in the cotton industry themselves.
The newest vegetable fabrics, as _ma_ (China grass), pina, _abaca_, or
Manila hemp, _agave_, jute, and that obtained from the palm tree, must
be tended with equal care to that of cotton. The _ma_, or China grass,
is obtained from the _Boehmeria nivea_, as also from the less known
_Boehmeria puya_. The fibers of this stalk, after preparing and
bleaching, have the whiteness of snow and the brilliancy of silk. By a
special process--the description of which we must for the present
leave in abeyance--the China grass can be transformed into a material
greatly resembling the finest quality of wool. The greatest advantage
afforded in the application of China grass is, moreover, that the
tissues produced with this fiber are much more easily washed than
silks, and in this operation they lose none of their beauty or their
quality.
The _abaca_ is produced from the fibrous parts of the bark of the wild
banana tree, found in the Philippines. Its botanical denomination is
_Musa troglodytarum_. The _abaca_ fiber is not spun or wrung, but is
jointed end to end. The threads are wound and subsequently beaten for
softening, and finally bleached by plunging in lime water for
twenty-four hours, and dried in the sun.
The _pina_ is a fiber obtained from the leaf of the anana tree
(_Bromelias ananas_), and is prepared in the same way as the abaca,
but extreme care must in this case be observed in culling the fibers,
in order to sort in accordance with their degree of fineness.
The Arabs manufacture the stuff for their tents with a mixture of
camel's hair and the fibrous flocks (kind of wadding) obtained from
the stalks of the wafer palm (the _Chamærops humilis_).
The tissues used by the Arabs are coarse and colored, but the palm
fibers--when freed from gluten, which makes them adhere more
strongly--are susceptible to divide in a most astonishing manner.
The _Agave americana_ is a coarse fiber, mostly used in France for the
manufacture of Gobelin carpets and the production of ropes. Great
efforts have been made to bleach it in a satisfactory manner, as is
done with the _Phormium tenax_, but the former kind of fiber resists
the ordinary treatment with lyes, etc., and an appropriate bleaching
process has only been discovered quite recently.
Jute, which by many is confounded with _Phormium tenax_, or New
Zealand lint, is a fiber which can be divided as finely as desired,
and can be most beautifully bleached.
The jute or Indian _paat_ is generally known as a fibrous and textile
fabric, obtained chiefly from Calcutta, and is similar in nature to
the _Corchorus capsularis_, an Oriental species, known in Oriental
India by the name of _hatta jute_ and _gheenatlapaat_. This fibrous
plant has the property of dividing into the finest parallel fibers,
which can be carded without difficulty, and may be said to have the
excellent properties of linen, hemp, and cotton at once. When properly
bleached, it has an aspect which is as beautiful as that of silk. A
mixture of silk and jute can be easily worked together, and can also
be mixed with such vegetable fibers as cotton and linen. An immense
quantity of flannel and other stuffs are now manufactured and imitated
with the different mixtures containing jute.
The _suun_ is a fiber of a plant in the form of a cane (_Crotalaria
juncea_), and the paat or _suncheepaat_ is the thread of a species of
spiral (_Corchorus olitarius_), sold under the name of jute tissues.
The cotton tissues lose about twenty-five per cent. of their weight in
bleaching, five per cent. of the substances are dissolved through
alkalies, and the other twenty per cent., which are not attacked
directly through the alkalies, are removed through chlorine, acids,
and the water itself. The linen and hemp tissues contain eighteen per
cent. of substances which are soluble in alkalies, and they lose from
twenty-seven to thirty per cent. of their weight when taken through
the consecutive bleaching operations.
The substances do not alone include the substances contained in the
fabric originally, but also such as are deposited in the preliminary
treatment of the fabrics, as dirt from the hands of the operator, and
gluten soluble in warm water; as also glue or gelatine, potash or
soda, starch, albumen, and sugar, used by weavers, etc., and which are
all soluble in water; further, such as greasy matters, calcareous
soap, coppery soap, resinous or gummo-resinous matters, and the yellow
and green coloring matters contained in textile fabrics, which are
soluble in caustic soda; and finally, the earthy constituents which
are soluble in acids.
The nature and composition of silk and wool is diametrically opposed
to that of the former. The silk is more of a gummy nature, and is
susceptible to decompose into a kind of gelatinous mass if specially
treated.
The yellow coloring principle in silk was found only to be contained
in a very small proportion, and consisting of several distinct bodies.
The wool contains, first, a fatty matter which is solid at an ordinary
temperature, and perfectly liquid at 60° C.; secondly, a fatty matter
which is liquid at 15° C.; thirdly, a fibrous substance which
essentially constitutes the wool in the strict sense of the word.
The wool at least contains three important principles, as it will be
known that the fibrous substance disengages sulphur and
hydro-sulphuric acid without losing its peculiar properties; and it,
therefore, appears probable that the sulphur entered as an element in
the composition of a body which is perfectly distinct from the fibrous
substance aforementioned.
In treating wool with nitric acid, and taking all possible precautions
to determine as accurately as possible the quantity of sulphuric acid
produced by the contents of sulphur in the wool by the reaction with
chloride of barium, it will be found to contain from 1.53 to 1.87 per
cent. of sulphur.--_Wool and Textile Fabrics._
* * * * *
THE PRODUCTION OF AMMONIA FROM COAL.[1]
By LUDWIG MOND.
[Footnote 1: A paper read at the annual general meeting of the
Society of Chemical Industry, London, July 10, 1889.]
As exemplifying to a certain extent the application of methodical
research to an industrial problem, I propose to bring before you
to-day an account of the work I have been engaged in for many years in
relation to the procuring of new and abundant supplies of ammonia, and
to investigations connected therewith.
Through the classic researches of Lawes and Gilbert, who proved, in
opposition to no less an authority than Liebig, that ammonia is a most
valuable manure which enables us not only to maintain, but to
multiply, the yield of our fields, and thus to feed on the same area a
much larger number of inhabitants, the immense importance of an
abundant supply of ammonia, more particularly for the Old World, with
its teeming population and worn-out soil, has been apparent to every
one.
For many years Europe has paid to South America millions upon millions
of pounds for ammonia in the shape of guano, and more recently, since
the supply of guano practically ceased, for nitrate of soda, which
effectually serves the same purpose as ammonia. During the past year
South America exported 750,000 tons of nitrate, of which 650,000 went
to Europe, representing a value of not less than 6,500,000l.
The problem of saving this immense expenditure to Europe, of making
ourselves independent of a country so far away for the supply of a
material upon which the prosperity of our agriculture--our most
important industry--depends, by supplying this ammonia from sources at
our own command, is certainly one of the most important which our
science has to solve.
It is more than 100 years since Berthollet ascertained that ammonia
consists of nitrogen and hydrogen, two elements which we have in great
abundance at our command, and innumerable attempts have been made
during this century to produce this valuable product by the direct
combination of the elements, as well as by indirect means. It has been
equally well known that we are in possession of three abundant sources
of nitrogen:
(1.) In the shape of matter of animal origin.
(2.) In the shape of matter of vegetable origin.
(3.) In the atmosphere, which contains no less than 79 per cent.
of uncombined nitrogen.
In olden times ammonia was principally obtained from animal matter,
originally in Egypt by the distillation of camel dung, later on from
urine, and from the distillation of bones and horn. The quantity so
obtained was very small and the products very expensive. The
introduction of coal gas for illumination gave us a considerable and
constantly increasing supply of ammonia as a by-product of the gas
manufacture, and until recently all practical efforts to increase our
supply of ammonia were directed toward collecting and utilizing in the
best possible manner the ammonia so obtained. The immense extension of
the coal gas industry all over the world has in this way put us into
possession of a very considerable amount of sulphate of ammonia,
amounting in Europe now to 140,000 tons per annum. In recent years
this has been augmented by the ammonia obtained by the distillation of
shale, by the introduction of closed ovens for the manufacture of
coke, combined with apparatus for condensing the ammonia formed in
this manufacture, and also by the condensation of the ammonia
contained in the gases from blast furnaces working with coal. But all
these new sources have so far added only about 40,000 tons of
sulphate of ammonia to our supply, making a total of 180,000 tons per
annum, of which about 120,000 are produced in the United Kingdom,
while we still import 650,000 tons of nitrate of soda, equivalent to
500,000 tons of sulphate of ammonia, to make up our requirements.
Many processes have from time to time been proposed to obtain ammonia
from other sources. The distillation of turf, which contains upward of
3 per cent. of nitrogen, has received much attention, and a large
number of inventors have endeavored to produce ammonia from the
nitrogen of the air; but none of these processes has to my knowledge
been successful on a manufacturing scale.
My attention was called to this subject at an early part of my career.
Already, as far back as 1861, I undertook experiments to utilize, for
the production of ammonia, waste leather, a waste material of animal
origin at once abundant and very rich in nitrogen, containing from 12
per cent. to 15 per cent. of this element. Distillation in iron
retorts yielded about half the nitrogen of this material in the form
of ammonia, the carbon remaining in the retorts containing still from
6 per cent. to 8 per cent. Distillation with a moderate quantity of
hydrate of lime increased the yield of ammonia only by 1 per cent. to
1½ per cent. A rather better result was obtained by distilling the
ground residual carbon with hydrate of lime, but this operation
proceeded very slowly, and the total yield of ammonia still remained
very far below the quantity theoretically obtainable, so that I came
to the conclusion that it was more rational to utilize the leather,
reduced to powder by mechanical means, by mixing it directly with
other manures.
A few years later I became connected with a large animal charcoal
works, in which sulphate of ammonia was obtained as a by-product. Here
again I was met with the fact that the yield of ammonia by no means
corresponded with the nitrogen in the raw material and that the
charcoal remaining in the retorts contained still about half as much
nitrogen as had been present in the bones used.
From this time forward my attention was for many years given
exclusively to the soda manufacture, and it was only in 1879 that I
again took up the question of ammonia. I then determined to submit the
various processes which had been proposed for obtaining ammonia from
the nitrogen of the air to a searching investigation, and engaged Mr.
Joseph Hawliczek to carry out the experimental work.
These processes may be broadly divided into three classes:
(1.) Processes which propose to combine nascent hydrogen with
nitrogen at high temperatures or by electricity, with or without
the presence of acid gases.
(2.) Processes in which nitrides are first formed, from which
ammonia is obtained by the action of hydrogen or steam.
(3.) Processes in which cyanides are first formed and the ammonia
obtained from these by the action of steam.
We began with an investigation of those processes in which a mixture
of steam and nitrogen or of steam and air is made to act upon coke at
a high temperature, sometimes in the presence of lime, baryta, or an
alkali, sometimes in the presence of hydrochloric acid.
Very numerous patents have been taken out in this direction and there
is no doubt that ammonia has been obtained by these processes by many
inventors, but as I was aware that coke contains a considerable
quantity of nitrogen, frequently as much as 1.5 per cent., which might
be the source of the ammonia obtained, I determined to carry on the
investigation in such a way as to make quite certain whether we
obtained the ammonia from the coke or from the nitrogen of the
atmosphere, or from both. For this purpose we made for every
experiment carried on by a mixture of nitrogen or air with steam
another experiment with steam alone, carefully excluding nitrogen from
the apparatus. A very large number of experiments carried on at
carefully determined temperatures, ranging from 500° to 1,200°C., and
in which the directions given by the various inventors were most
carefully observed, all led to the same result, viz., that the
quantities of ammonia obtained were the same whether nitrogen was
introduced into the apparatus with the steam or whether steam alone
was used, thus proving conclusively that the ammonia obtained was
derived from the nitrogen contained in the coke.
Further, on carefully determining the nitrogen in the coke used, it
was found that the quantity of ammonia we had obtained in burning coke
in a current of nitrogen and steam very nearly corresponded with the
total nitrogen in the coke, so that we subsequently made our nitrogen
determinations in the coke by simply burning it in a current of steam.
A process belonging to this class, proposed by Hugo Fleck, in which a
mixture of carbonic oxide, steam, and nitrogen is made to pass over
lime at a moderate red heat in order to obtain ammonia, was also
carefully tried. It was claimed for this process that it produced
nascent hydrogen at temperatures at which the ammonia is not
dissociated, and for this reason succeeded where others had failed. We
found that a considerable amount of hydrogen was obtained in this way
at a temperature not exceeding 350°C., and that the reaction was
nearly complete at 500°C.; but although we tried many experiments over
a great range of temperatures, we never obtained a trace of ammonia by
this process.
Among experiments with processes of the second class, based upon the
formation of nitrides and their subsequent decomposition, the nitrides
of boron and titanium had received most attention from inventors. The
nitride of boron, which is obtained by treating boracic acid with
carbon in the presence of nitrogen, when acted upon by steam, forms
boracic acid again and yields the whole of its nitrogen in the form of
ammonia, but the high temperature at which the first reaction takes
place, and the volatility of boracic acid in a current of steam, make
it impossible to utilize this reaction industrially.
There seemed to be a better chance for a process patented by M.
Tessier du Mothay, who proposed to bring a mixture of nitrogen and
hydrogen into contact with titanium nitride and thus to form ammonia
continuously. Titanium is the only element of which we know at present
several combinations with nitrogen, and the higher of these does, on
being acted upon by a current of hydrogen at an elevated temperature,
produce ammonia and a lower nitride of titanium; but this lower
nitride does not absorb nitrogen under any of the conditions under
which we tried it, which explains the fact that if we passed a current
of hydrogen and nitrogen over the higher nitride, we at first obtained
a quantity of ammonia corresponding to the quantity which the nitride
would give with hydrogen alone, but that the formation of ammonia then
ceased completely.
Thus far we had quite failed to get the nitrogen of the air into
action.
With the third class of processes, however, based upon the formation
in the first instance of cyanides, we found by our very first
experiments that the nitrogen of the atmosphere can be easily led into
combination. A few experiments showed that the cyanide of barium was
much more readily formed than any other cyanide; so we gave our full
attention from this time to the process for obtaining ammonia by means
of cyanide of barium invented by MM. Margueritte and Sourdeval. This
process consists in heating a mixture of carbonate of barium with
carbon in the presence of nitrogen, and subsequently treating the
cyanide of barium produced with steam, thus producing ammonia and
regenerating the carbonate of barium. A great difficulty in this
process is that the carbonate of barium fuses at high temperatures,
and when fused attacks fireclay goods very powerfully.
We found that this can be overcome by mixing the carbonate of barium
with a sufficient quantity of carbon and a small quantity of pitch,
and that in this way balls can be made which will not fuse, so that
they can be treated in a continuous apparatus in which the broken
briquettes can be charged from the top, and after treatment can be
withdrawn from the bottom.
We found that the formation of cyanides required a temperature of at
least 1,200° C., and proceeded most readily at 1,400° C., temperatures
which, although difficult to attain, are still quite within the range
of practical working, and we found no difficulty in obtaining a
product containing 30 per cent. of barium cyanide, corresponding to a
conversion into cyanide of 40 per cent. of the barium present.
We found, however, that the cyanide when exposed to the atmosphere at
a temperature above 300° C. is readily destroyed under reformation of
carbonate of barium, so that it is absolutely necessary to cool it
down to this temperature before exposing it to the atmosphere, a fact
of great importance that had hitherto been overlooked.
The operation for producing ammonia and regenerating the carbonate of
barium by acting upon the cyanide with steam offers no difficulty
whatever, and if the temperature is not allowed to exceed 500° C., the
results are quantitative. The regenerated carbonate of barium acts
actually better than the ground witherite used in the first instance,
and if care is taken that no impurities are introduced by the pitch
which is used to remake the briquettes and to replace the small amount
of carbon consumed at each operation, I see no reason why it should
not continue to act for a very long time.
The cyanide is not acted on by carbonic oxide, but carbonic acid
destroys it at high temperatures, so that it is not possible to
produce it by heating the briquettes directly in a flame free from
oxygen, but containing carbonic acid. The process has, therefore, to
be carried out in closed vessels, and I designed for this purpose the
following apparatus:
Clay retorts of moderate dimensions and thin walls are placed
vertically in a furnace, passing through the hearth as well as through
the arch of the furnace. These are joined at the bottom to cast iron
retorts of the same shape as the earthenware retort. Through a cast
iron mouthpiece on the top of the retort the material was introduced,
while in the cast iron retort below the material was cooled to the
necessary temperature by radiation and by the cold nitrogen gas
introduced into the bottom of it. The lower end of the cast iron
retort was furnished with an arrangement for taking out from time to
time small quantities of the material, while fresh material was in the
same proportion fed in at the top. As a source of nitrogen I used the
gases escaping from the carbonating towers of the ammonia-soda
process. The formation of cyanide of barium from barium carbonate,
carbon, and nitrogen absorbs a very large amount of heat--no less than
97,000 calories per equivalent of the cyanide formed--which heat has
to be transmitted through the walls of the retort. I therefore
considered it necessary to use retorts with very thin walls, but I did
not succeed in obtaining retorts of this description which would
resist the very high temperatures which the process requires, and for
this reason I abandoned these experiments. I was at that time not
acquainted with the excellent quality of clay retorts used in zinc
works, with which I have since experimented for a different purpose. I
have no doubt that with such retorts the production of cyanides by
this process can be carried out without great difficulty.
I believe that the process will prove remunerative for the manufacture
of cyanogen products, which, if produced more cheaply, may in the
future play an important role in organic synthesis, in the extraction
of noble metals, and possibly other chemical and metallurgical
operations.
The process certainly also offers a solution of the problem of
obtaining ammonia from the nitrogen of the atmosphere, but whether
this can be done with satisfactory commercial results is a question I
cannot at present answer, as I have not been able to secure the data
for making the necessary calculations.
I am the more doubtful about this point, as in the course of our
investigations I have found means to produce ammonia at small cost and
in great abundance from the immense store of combined nitrogen which
we possess in our coal fields.
Among the processes for obtaining ammonia from the nitrogen of the air
which we investigated, was one apparently of great simplicity,
patented by Messrs. Rickman and Thompson. These gentlemen state that
by passing air and steam through a deep coal fire, the nitrogen so
passed through is to a certain extent converted into ammonia. In
investigating this statement we found that the process described
certainly yields a considerable quantity of ammonia, but when we
burned the same coal at a moderate temperature by means of steam
alone in a tube heated from the outside, we obtained twice as much
ammonia as we had done by burning it with a mixture of air and steam,
proving in this case, as in all others, the source of the ammonia to
have been the nitrogen contained in the coal. The quantity of ammonia
obtained was, however, so large that I determined to follow up this
experience, and at once commenced experiments on a semi-manufacturing
scale to ascertain whether they would lead to practical and economic
results.
I came to the conclusion that burning coal by steam alone at a
temperature at which the ammonia formed should not be dissociated,
although it yielded more ammonia, would not lead to an economic
process, because it would require apparatus heated from the outside,
of great complication, bulk, and costliness, on account of the immense
quantity of raw material to be treated for a small amount of ammonia
obtainable.
On the other hand, if the coal could be burned in gas producers by a
mixture of air and steam, the plant and working of it would be simple
and inexpensive, the gas obtained could be utilized in the same way as
ordinary producer gas, and would pay to a large extent for the coal
used in the operation, so that although only one-half of the ammonia
would be obtained, it seemed probable that the result would be
economical.
I consequently constructed gas producers and absorbing plant of
various designs and carried on experiments for a number of years.
These experiments were superintended by Mr. G. H. Beckett, Dr. Carl
Markel, and, during the last four years, by Dr. Adolf Staub, to whose
zeal and energy I am much indebted for the success that has been
achieved. The object of these experiments was to determine the most
favorable conditions for the economic working of the process with
respect to both the cost of manufacture as well as the first cost and
simplicity of plant. The cost of manufacture depends mainly upon the
yield of ammonia, as the expenses remain almost the same whether a
large or a small amount of ammonia is obtained; the only other item of
importance is the quantity of steam used in the process. We found the
yield of ammonia to vary with the temperature at which the producer
was working, and to be highest when the producer was worked as cool as
was compatible with a good combustion of the fuel. The temperature
again depended upon the amount of steam introduced into the producer,
and of course decreased the more steam increased. We obtained the best
practical results by introducing about two tons of steam for every ton
of fuel consumed. We experimented upon numerous kinds of fuel, common
slack and burgy of the Lancashire, Staffordshire, and Nottinghamshire
districts. We found not much difference in the amount of nitrogen
contained in these fuels, which varied between 1.2 and 1.6 per cent.,
nor did we find much difference in the ammonia obtained from these
fuels if worked under similar conditions. Employing the quantity of
steam just named we recovered about half the nitrogen in the form of
ammonia, yielding on an average 0.8 per cent. of ammonia, equal to 32
kilos, of sulphate per ton of fuel. In order to obtain regular results
we found it necessary to work with a great depth of fuel in the
producers, so that slight irregularities in the working would not
affect results. Open burning kinds of slack do of course work with the
greater ease, but there is no difficulty in using a caking fuel, as
the low temperature at which the producers work prevents clinkering
and diminishes the tendency of such fuels to cake together.
The quantity of steam thus required to obtain a good yield of ammonia
is rather considerable, and threatened to become a serious item of
expense. Only one-third of this steam is decomposed, in its passage
through the producer, and two-thirds remain mixed with the gases which
leave the producer. My endeavors were consequently directed toward
finding means to recover this steam, and to return it to the
producers, and also to utilize the heat of the gases which leave the
producers with a temperature of 450° to 500° C., for raising steam for
the same purpose. The difficulties in the way of attaining this end
and at the same time of recovering, in a simple manner, the small
amount of ammonia contained in the immense volume of gas we have to
deal with, were very great. We obtain from one ton of coal 160,000
cubic feet of dry gas at 0° C. and atmospheric pressure. The steam
mixed with this gas as it leaves the producer adds another 80,000
cubic feet to this, and the large amount of latent heat in this
quantity of steam makes the problem still more difficult. The
application of cooling arrangements, such as have been successfully
applied to blast furnace gases, in which there is no steam present,
and which depend upon the cooling through the metallic sides of the
apparatus, is here practically out of the question. After trying a
number of different kinds of apparatus, I have succeeded in solving
the problem in the following way:
The gases issuing from the producers are led through a rectangular
chamber partly filled with water, which is thrown up in a fine spray
by revolving beaters so as to fill the whole area of the chamber. This
water, of course, becomes hot; a certain quantity of it evaporates,
the spray produced washes all dust and soot out of the gases, and also
condenses the fixed ammonia. The water thus becomes, to a certain
degree, saturated with ammonia salts, and a certain portion of it is
regularly removed from the chamber and distilled with lime to recover
the ammonia.
[Illustration: Longitudinal Section of Plant for obtaining Ammonia
from Gas Producers.
Cross Section through Gas Producers.]
This chamber is provided with water lutes, through which the tar
condensed in it is from time to time removed. From this chamber the
gases, which are now cooled down to about 100° C., and are loaded with
a large amount of water vapor, are passed through a scrubber filled
with perforated bricks, in which the ammonia contained in the gases is
absorbed by sulphuric acid. In this scrubber a fairly concentrated
solution of sulphate of ammonia containing 36 to 38 per cent. is used,
to which a small quantity of sulphuric acid is added, so that the
liquid leaving the scrubber contains only 2.5 per cent. of free acid.
This is necessary, as a liquid containing more acid would act upon the
tarry matter and produce a very dark-colored solution. The liquid
running from the scrubber is passed through a separator in which the
solution of sulphate of ammonia separates from the tar. The greater
portion of the clear liquid is, after adding a fresh quantity of acid
to it, pumped back through the scrubber. A certain portion of it is,
after treatment with a small quantity of heavy tar oils, which take
the tarry matter dissolved in it out, evaporated in conical lead-lined
pans furnished with lead steam coils, and which are kept constantly
filled by the addition of fresh liquor until the whole mass is thick.
This is then run out on a strainer and yields, after draining and
washing with a little water, a sulphate of ammonia of very fair
quality, which finds a ready sale. The mother liquor, which contains
all the free acid, is pumped back to the scrubber.
The gas on entering this scrubber contains only 0.13 volume per cent.
of ammonia, and on leaving the scrubber it contains not more than
one-tenth of this quantity. Its temperature has been reduced to
80° C., and is fully saturated with moisture, so that practically no
condensation of water takes place in the scrubber. The gas is next
passed through a second scrubber filled with perforated wood blocks.
In this it meets with a current of cold water which condenses the
steam, the water being thereby heated to about 78° C. In this scrubber
the gas is cooled down to about 40°-50° C., and passes from it to the
gas main leading to the various places where it is to be consumed. The
hot water obtained in this second scrubber is passed through a vessel
suitably constructed for separating the tar which is mixed with it,
and is then pumped through a third scrubber, through which, in an
opposite direction to the hot water, cold air is passed. This is
forced by means of a Roots blower through the scrubber into the
producer.
The air gets heated to about 76° C. and saturated with moisture at
that temperature by its contact with the hot water, and the water
leaves this third scrubber cold enough to be pumped back through the
second scrubber. The same quantity of water is thus constantly used
for condensing the water vapor in one scrubber and giving it up to the
air in the other. In this way we recover and return to the producer
fully two-thirds of the steam which has been originally introduced, so
that we have to add to the air, which has thus been loaded with
moisture, an additional quantity of steam equal to only one-third of
the total quantity required before it enters the producer. This
additional quantity of steam, which amounts to 0.6 ton of steam for
every ton of fuel burnt, we obtain as exhaust steam from the engines
driving the blowers and pumps required for working the plant.
The gas producers which I prefer to use are of rectangular shape, so
that a number of them can be put into a row. They are six feet wide
and 12 feet long inside. The air is introduced and the ashes removed
at the two small sides of the producer which taper toward the middle
and are closed at the bottom by a water lute of sufficient depth for
the pressure under which the air is forced in, equal to about 4 inches
of water. The ashes are taken out from underneath the water, the
producers having no grate or fire bars at all. The air enters just
above the level of the water through a pipe connected with the blower.
These small sides of the producer rest upon cast iron plates lined to
a certain height with brickwork, and this brickwork is carried by
horizontal cast iron plates above the air entrance. In this way a
chamber is formed of triangular shape, one side of which is closed by
the ashes, and thus the air is distributed over the whole width of the
producer.
The gas is taken out in the middle of the top of the producer by an
iron pipe, and fuel charged in by hoppers on both sides of this pipe.
Between the pipe and the hoppers two hanging arches are put into the
producers a certain distance down, and the fuel is kept above the
bottom level of these hanging arches. This compels the products of
distillation, produced when fresh fuel is charged in, to pass through
the incandescent fuel between the two hanging arches, whereby the
tarry products are to a considerable extent converted into permanent
gas, and the coal dust arising from the charging is kept back in the
producer.
The details of construction of this plant will be easily understood by
reference to the diagrams before you.
The fuel we use is a common kind of slack, and contains, on an
average, 33.5 per cent. of volatile matter, including water, and 11.5
per cent. of ashes, leaving 55 per cent. of non-volatile carbon.
The cinders which we take out of the producer contain, on an average,
33 per cent. of carbon. Of this we recover about one-half by riddling
or picking, which we return to the producer. The amount of unburnt
carbon lost in the cinders is thus not more than 3 per cent. to 4 per
cent. on the weight of fuel used.
The gas we obtain contains, in a dry state, on an average, 15 per
cent. of carbonic acid, 10 per cent. of carbonic oxide, 23 per cent.
of hydrogen, 3 per cent. of hydrocarbons, and 49 per cent. of
nitrogen.
The caloric value of this gas is very nearly equal to 73 per cent. of
the caloric value of the fuel used, but in using this gas for heating
purposes, such as raising steam or making salt, we utilize the heat it
can give very much better than in burning fuel, as we can completely
burn it with almost the theoretical quantity of air, so that the
products of combustion resulting do not contain more than 1 to 2 per
cent. of free oxygen. Consequently the heat escaping into the chimney
is very much less than when fuel is burnt direct, and we arrive at
evaporating, by means of the gas, 85 per cent. of the water that we
would evaporate by burning the fuel direct, in ordinary fireplaces.
We have, however, to use a certain quantity of steam in the producers
and in evaporating the sulphate of ammonia liquors, which has to be
deducted from the steam that can be raised by the gas in order to get
at the quantity of available steam therefrom obtainable. The former
amounts, as already stated, to 0.6 ton, the latter to 0.1 ton of steam
per ton of fuel burnt, making a total of 0.7 ton. The gas obtained
from one ton of fuel evaporates 5.8 tons of water in good steam
boilers, working at a rate of evaporation of 50 to 55 tons per 24
hours under 90 lb. pressure. Deducting from this the 0.7 ton necessary
for working the plant leaves an available amount of steam raised by
the gas from one ton of fuel of 5.1 tons, equal to 75 per cent. of the
steam that we can obtain from the same fuel by hand firing.
In addition to the gas, we obtain about 3 per cent. of tar from the
fuel. This tar is very thick, and of little commercial value. It
contains only 4 per cent. of oils volatile below 200° C., and 38 per
cent. of oils of a higher boiling point, consisting mostly of creosote
oils very similar to those obtained from blast furnaces; and only
small quantities of anthracene and paraffin wax.
I have made no attempts to utilize this tar except as fuel. It
evaporates nearly twice as much water as its weight of coal, and we
have thus to add its evaporative efficiency to that of the gas given
above, leading to a total of about 80 per cent. of the evaporative
efficiency of the fuel used in the producers. The loss involved in
gasifying the fuel to recover the ammonia therefrom amounts thus to 20
per cent. of the fuel used. This means that, where we have now to burn
100 tons of fuel, we shall have to burn 125 tons in the producers in
order to obtain ammonia equal to about half the nitrogen contained
therein. Our actual yield of ammonia on a large scale amounting on an
average to 32 kilos., equal to 70.6 lb. per ton of fuel, 125 tons of
fuel will turn out 4 tons of sulphate of ammonia. We thus consume 6.25
tons of fuel for every ton of sulphate obtained, or nearly the same
quantity as is used in producing a ton of caustic soda by the Le Blanc
process--a product not more than half the value of ammonium sulphate.
At present prices in Northwich this fuel represents a value of 35s. If
we add to this the extra cost of labor over and above the cost of
burning fuel in ordinary fireplaces, the cost of sulphuric acid, bags,
etc., we come to a total of 4l. 10s. to 5l. per ton of sulphate of
ammonia, which at the present selling price of this article, say 12l.
per ton, leaves, after a liberal allowance for wear and tear of plant,
an ample margin of profit. With a rise in the price of fuel, this
margin, however, rapidly decreases, and the working of the process
will, of course, be much more expensive on a small scale, as will also
be the cost of the plant, which under all circumstances is very
considerable. The great advantages incidental to this process over and
above the profit arising from the manufacture of sulphate of ammonia,
viz., the absolute impossibility of producing smoke and the great
regularity of the heating resulting from the use of gas, are,
therefore, as far as I can see for the present, only available for
large consumers of cheap fuel.
We have tried many experiments to produce hydrochloric acid in the
producers, with the hope of thereby increasing the yield of ammonia,
as it is well known that ammonium chloride vapor, although it consists
of a mixture of ammonia gas and hydrochloric acid gas, is not at all
dissociated at temperatures at which the dissociation of ammonia alone
has already taken place to a considerable extent.
I had also hoped that I might in this way produce the acid necessary
to combine with the ammonia at very small cost. For this purpose we
moistened the fuel used with concentrated brine, and also with the
waste liquors from the ammonia soda manufacture, consisting mainly of
chloride of calcium; and we also introduced with the fuel balls made
by mixing very concentrated chloride of calcium solution with clay,
which allowed us to produce a larger quantity of hydrochloric acid in
the producer than by the other methods.
We did in this way succeed in producing hydrochloric acid sometimes
less and sometimes more than was necessary to combine with the
ammonia, but we did not succeed in producing with regularity the exact
amount of acid necessary to neutralize the ammonia. When the ammonia
was in excess, we had therefore to use sulphuric acid as before to
absorb this excess, and we were never certain that sometimes the
hydrochloric acid might not be in excess, which would have
necessitated to construct the whole plant so that it could have
resisted the action of weak hydrochloric acid--a difficulty which I
have not ventured to attack. The yield of ammonia was not in any case
increased by the presence of the hydrochloric acid. This explains
itself if we consider that there is only a very small amount of
ammonia and hydrochloric acid diffused through a very large volume of
other gases, so that the very peculiar protective action which the
hydrochloric acid does exercise in retarding the dissociation of
ammonia in ammonium chloride vapor, where an atom of ammonia is always
in contact with an atom of hydrochloric acid, will be diminished
almost to zero in such a dilute gas where the atoms of hydrochloric
acid and ammonia will only rarely come into immediate contact with
each other.
When we burnt coke by a mixture of air and steam in presence of a
large excess of hydrochloric acid, the yield of ammonia certainly was
thereby considerably increased, but such a large excess cannot be used
on an industrial scale. I have therefore for the present to rest
satisfied with obtaining only half the nitrogen contained in the fuel
in the form of ammonia.
The enormous consumption of fuel in this country--amounting to no less
than 150 million tons per annum--would at this rate yield as much as
five million tons of sulphate of ammonia a year, so that if only
one-tenth of this fuel would be treated by the process, England alone
could supply the whole of the nitrogenous compounds, sulphate of
ammonia, and nitrate of soda at present consumed by the Old World. As
the process is especially profitable for large consumers of fuel
situated in districts where fuel is cheap, it seems to me particularly
suitable to be adopted in this country. It promises to give England
the privilege of supplying the Old World with this all-important
fertilizer, and while yielding a fair profit to the invested capital
and finding employment for a considerable number of men, to make us,
last not least, independent of the New World for our supply of so
indispensable a commodity.
Before leaving my subject, I will, if you will allow me, give you in a
few words a description of two other inventions which have been the
outcome of this research. While looking one day at the beautiful,
almost colorless, flame of the producer gas burning under one of our
boilers, it occurred to me that a gas so rich in hydrogen might be
turned to better use, and that it might be possible to convert it
direct into electricity by means of a gas battery.
You all know that Lord Justice Grove showed, now fifty years ago, that
two strips of platinum partly immersed in dilute sulphuric acid, one
of which is in contact with hydrogen and the other with oxygen,
produce electricity. I will not detain you with the many and varied
forms of gas batteries which Dr. Carl Langer (to whom I intrusted this
investigation) has made and tried during the last four years, in order
to arrive at the construction of a gas battery which would give a
practical result, but I will call your attention to the battery before
me on the table, which is the last result of our extended labors in
this direction, and which we hope will mark a great step in advance in
the economic production of electricity.
The distinguishing feature of this battery is that the electrolyte is
not employed as a mobile liquid, but in a quasi-solid form, and it is,
therefore, named dry gas battery. It consists of a number of elements,
which are formed of a porous diaphragm of a non-conducting material
(in this instance plaster of Paris), which is impregnated with dilute
sulphuric acid. Both sides of this diaphragm are covered with very
fine platinum leaf perforated with very numerous small holes, and over
this a thin film of platinum black. Both these coatings are in contact
with frameworks of lead and antimony, insulated one from the other,
which conduct the electricity to the poles of the battery.
A number of these elements are placed side by side, with
non-conducting frames intervening, so as to form chambers through
which the hydrogen gas is passed along one side of the element and air
along the other.
This peculiar construction allows us to get a very large amount of
duty from a very small amount of platinum. One of the batteries before
you, consisting of seven elements, with a total effective surface of
half a square meter, contains 2½ grammes of platinum leaf and 7
grammes of platinum black, a total of 9½ grammes of platinum, and
produces a current of 2 amperes and 5 volts, or 10 watts, when the
outer resistance is properly adjusted. This current is equal to nearly
50 per cent. of the total energy obtainable from the hydrogen absorbed
in the battery.
In order to maintain a constant current, we have from time to time
(say once an hour) to interchange the gases, so as to counteract the
disturbing influence produced by the transport of the sulphuric acid
gas from one side of the diaphragm to the other. This operation can
easily be performed automatically by a commutator worked by a clock.
The water produced in the battery by the oxidation of the hydrogen is
carried off by the inert gas mixed with the hydrogen, and by the air,
of which we use a certain excess for this purpose. This is important,
as if the platinum black becomes wet, it loses its absorbing power for
the gases almost completely and stops the work of the battery. To
avoid this was in fact the great difficulty in designing a powerful
gas battery, and all previous constructions which employed the
electrolyte as a mobile liquid failed in consequence.
The results obtained by our battery are practically the same whether
pure oxygen and hydrogen or air and gases containing 25 per cent. of
hydrogen are used; but we found that the latter gases must be
practically free from carbonic oxide and hydrocarbons, which both
interfere very much with the absorbing power of the platinum black.
We had thus to find a cheap method of eliminating these two gases from
the producer gas, and converting them at the same time into their
equivalent of hydrogen. The processes hitherto known for this purpose,
viz., passing a mixture of such gases with steam over lime (which I
mentioned some time ago) or over oxide of iron or manganese, require
high temperatures, which render them expensive, and the latter do not
effect the reaction to a sufficient extent for our purpose.
We have succeeded in attaining our object at a temperature below that
at which the gases leave my producers, viz., at 350° C. to 450° C., by
passing the producer gases, still containing a considerable excess of
steam, over metallic nickel or cobalt. These metals have the
extraordinary property of decomposing almost completely, even at the
low temperature named, carbonic oxide into carbon and carbonic acid
and hydrocarbons into carbon and hydrogen.
In order to carry the process out with small quantities of nickel and
cobalt, we impregnate pumice stone or similar material with a salt of
nickel or cobalt, and reduce this by means of hydrogen or producer
gas. These pieces of pumice stone are filled into a retort or chamber
and the hot gases passed through them. As the reaction produces heat,
it is not necessary to heat the chambers or retorts from the outside
when the necessary temperature has once been attained. This process
has not yet been carried out on a large scale, but the laboratory
experiments have been so satisfactory that we have no doubt as to its
complete success. It will enable us to obtain gases containing 36 per
cent. to 40 per cent. of hydrogen and practically free from carbonic
oxide and hydrocarbons from producer gas at a very small cost, and
thus to make the latter suitable for the production of electricity by
our gas battery. We obtain, as stated before, 50 per cent. of the
energy in the hydrogen absorbed in the battery in the form of
electricity, while, if the same gas was consumed under steam boilers
to make steam, which, as I have shown before, could in this way be
raised cheaper than by burning fuel direct, and if this steam was
turned into motive power by first-rate steam engines, and the motive
power converted into electricity by a dynamo, the yield of electricity
would in the most favorable case not exceed 8 per cent. of the energy
in the gas. I hope that this kind of battery will one day enable us to
perform chemical operations by electricity on the largest scale, and
to press this potent power into the service of the chemical
industries.
The statement is frequently made that "Necessity is the mother of
invention." If this has been the case in the past, I think it is no
longer so in our days, since science has made us acquainted with the
correlation of forces, teaching us what amount of energy we utilize
and how much we waste in our various methods for attaining certain
objects, and indicating to us where and in what direction and how far
improvement is possible; and since the increase in our knowledge of
the properties of matter enables us to form an opinion beforehand as
to the substances we have available for obtaining a desired result.
We can now foresee, in most cases, in what direction progress in
technology will move, and in consequence the inventor is now
frequently in advance of the wants of his time. He may even create new
wants, to my mind a distinct step in the development of human culture.
It can then no longer be stated that "Necessity is the mother of
invention;" but I think it may truly be said that the steady,
methodical investigation of natural phenomena is the father of
industrial progress.
Sir Lowthian Bell, Bart., F.R.S., in moving a vote of thanks, said
that the meeting had had the privilege of listening to a description
of results obtained by a man of exceptional intelligence and learning,
supplemented by that devotion of mind which qualified him to pursue
his work with great energy and perseverance. The importance of the
president's address could not possibly be overrated. At various
periods different substances had been put forward as indications of
the civilization of the people. He remembered hearing from Dr. Ure
that he considered the consumption of sulphuric acid to be the most
accurate measure of the civilization of the people.
In course of time sulphuric acid gave way to soap, the consumption of
which was probably still regarded as the great exponent of
civilization by such of his fellow citizens as had thereby made their
name. From what he had heard that morning, however, he should be
inclined to make soap yield to ammonia, as sulphuric acid had in its
time succumbed to soap. For not only was ammonia of great importance
to us as a manufacturing nation, but it almost appeared to be a
condition of our existence. England had a large population
concentrated on an area so small as to make it almost a matter of
apprehension whether the surface could maintain the people upon it.
We were now importing almost as much food as we consumed, and were
thus more and more dependent on the foreigner. Under certain
conditions this would become a very serious matter, and thus any one
who showed how to produce plenty of ammonia at a cheap rate was a
benefactor to his country. Mr. Mond's process seemed to come nearer to
success than any which had preceded it, and it needed no words from
him to induce the meeting to accord a hearty vote of thanks to the
president for his admirable paper.
Mr. J. C. Stevenson, M.P., in seconding the motion, said that no paper
could be more interesting and valuable to the society than that
delivered by the president. It opened out a future for the advancement
of chemical industry which almost overcame one by the greatness of its
possibilities. Mr. Mond had performed an invaluable service by
investigating the various methods proposed for the manufacture of
ammonia, and clearing the decks of those processes supposed by their
inventors to be valuable, but proved by him to be delusive. It gave
him hearty pleasure therefore to second the vote of thanks proposed by
Sir Lowthian Bell.
The vote having been put and carried by acclamation, after a brief
reply from the president:
The secretary read the report of the scrutators, which showed that 158
ballot papers had been sent in, 154 voting for the proposed list
intact, and four substituting other names. The gentlemen nominated in
the list issued by the Council were therefore declared elected.
* * * * *
In his brief report for the year ending May 1, 1889, the director of
the Pasteur Institute, Paris, announces the treatment of 1,673
subjects, of whom 6 were seized with rabies during and 4 within a
fortnight after the process. But 3 only succumbed after the treatment
had been completely carried out, making 1 death in 554, or, including
all cases, 1 in 128.
* * * * *
ALKALI MANUFACTORIES.
When the alkali, etc., Works Regulation Act was passed in 1881, it was
supposed that the result would be that the atmosphere in the districts
where such works are situated would be considerably improved, and,
consequently, that vegetation would have a better chance in the
struggle for existence, and the sanitary conditions of human dwellings
would be advanced. In all these respects the act has been a success.
But perhaps the most notable result is the effect which the act and
those which have preceded it have had upon the manufactures which they
control.
This was not anticipated by manufacturers, but now one of the
principal of them (Mr. A. M. Chance) has stated that "Government
inspection has not only led to material improvement in the general
management of chemical works, but it has also been in reality a
distinct benefit to, rather than a tax upon, the owners of such
works."
This expression of opinion is substantiated by the chief inspector
under the act, whose report for last year has recently been laid
before the local government board.
There are 1,057 works in the United Kingdom which are visited by the
inspectors, and in only two of these during 1888 did the neglect to
carry out the inspectors' warnings become so flagrant as to call for
legal interference; viz., in the case of Thomas Farmer & Co.
(limited), Victoria Docks, E., who were fined 20l. and costs for
failing to use the "best practicable means" for preventing the escape
of acid gas from manure plant; and in the case of Joseph Fison & Co.,
Bramford, who were fined 50l. and costs for excessive escape of acid
gas from sulphuric acid plant. There were seven other cases, but these
were simply for failure to register under the act.
It is very evident, therefore, that from a public point of view the
act is splendidly successful, and from the practical or scientific
side it is no less satisfactory.
Of the total number of chemical works (1,057) 866 are registered in
England, 131 in Scotland, and 44 in Ireland--a decrease in the case of
Scotland of 8, and in Ireland of 2 from the previous year, while
England has increased by 1. This must not, however, be taken as a sign
of diminished production, because there is a tendency for the larger
works to increase in size and for the smaller ones to close their
operations. The principal nuisances which the inspectors have to
prevent are the escape of hydrochloric acid gas from alkali works and
of sulphurous gas from vitriol and manure works.
The alkali act forbids the manufacturer to allow the escape of more
than 5 per cent. of the hydrochloric acid which he produces, or that
that acid must not exist to a greater extent than 0.2 grain in 1 cubic
foot of air, steam, or chimney gas which accompanies. The inspectors'
figures for last year show that the percentage of the acid which
escaped amounted to only 1.96 of the total produced, which is equal to
0.089 grain per cubic foot, and much below the figures for previous
years. The figures in regard to sulphurous gas are equally
satisfactory. The act allows 4 grains of sulphuric anhydride (SO3) per
cubic foot to escape into the air, and last year's average was only
0.737 grain, or less than a fifth of the limit.
Of course it is now the aim of the Leblanc alkali manufacturers to
reduce the escape of hydrochloric acid to the lowest possible amount,
as their profits depend solely upon the sale of chlorine products,
soda products being sold at a loss. In this connection it is
interesting to note that the amount of common salt manufactured in the
United Kingdom in 1888 was 2,039,867 tons, and of this nearly 600,000
tons were taken by Leblanc soda makers, and over 200,000 tons by the
ammonia-soda makers. The figures are very largely in excess of
previous years, and indicate a gratifying growth in trade.
The salt used in the Leblanc process yields the hydrochloric acid, and
that in the ammonia-soda method none, so that we may put down the
theoretical production of acid as 380,000 tons, 7,600 tons of which
was allowed to escape.
What was a mere trace in the chimney gases amounts, therefore, to a
good round figure at the end of a year, and if it were converted into
bleaching powder it would be worth nearly 150,000l. These figures are,
it should be understood, based on theory, but they serve to show to
what importance a gas has now reached which twenty-five years ago was
a perfect incubus to the manufacturers, and wrought desolation in the
country sides miles and miles around the producing works. There has
long been an expectation that the ammonia-soda makers would add the
manufacture of bleaching powder to their process, but they appear to
be as far as ever from that result, and meanwhile the Leblanc makers
are honestly striving to utilize every atom of the valuable material
which they handle. Hence the eagerness to recover the sulphur from
tank waste by one or other of the few workable processes which have
been proposed.
This waste contains from 11 to 15 per cent. of sulphur, and when it is
stated that the total amount of tank waste produced yearly is about
750,000 tons, containing about 100,000 tons of sulphur, it will be
seen how large is the reward held out to the successful manipulator.
Moreover, the value of the sulphur that might possibly be saved is not
the only prize held out to those who can successfully deal with the
waste, for this material is not only thrown away as useless, but much
expense is incurred in the throwing.
In Lancashire and in other inland districts land must be found on
which to deposit it, and the act of depositing is costly, for unless
it is beaten together so as to exclude the air, an intolerable
nuisance arises from it. The cost of haulage and deposit on land
varies, according to the district, from 1s. to 1s. 6d. a ton. In
Widnes it is about 1s.
In the Newcastle district the practice is to carry this material out
to sea at a cost of about 4d. a ton.
Mr. Chance's process for the recovery of sulphur from the waste
signalizes the centenary of the Leblanc process; Parnell and Simpson
are following in his wake, and lately Mr. F. Gossage, of Widnes, has
been working on a process for the production of alkali, which enables
him to save the sulphur of the sulphuric acid. In his process a
mixture of 70 parts Leblanc salt cake (sulphate of soda) and 30 parts
common salt is mixed with coal and heated in a furnace, and so reduced
to sulphide of sodium. The resulting "ash" is then dissolved in water
and exposed to the action of carbonic acid, when sulphureted hydrogen
is given off, to be dealt with as in Mr. Chance's sulphur process,
while bicarbonate of soda is formed and separates by precipitation
from the solution of undecomposed common salt.
Ere long it is expected this new method will be in active operation in
some Leblanc works, the plant of which will, in all probability, be
utilized. It has these great advantages: The absence of lime, the
recovery of the sulphur used in the first instance and the consequent
absence of the objectionable tank waste. Thus a bright promise is held
out that the days of alkali waste are numbered, and that the air in
certain parts of Lancashire will be more balmy than it has been in the
memory of the oldest inhabitant.--_Chemist and Druggist._
* * * * *
THE FUELS OF THE FUTURE.
It is undeniable that in this country, at least, we are accustomed to
regard coal as the chief, and, indeed, the only substance which falls
to be considered under the name of fuel. In other countries, however,
the case is different. Various materials, ranging from wood to oil,
come within the category of material for the production of heat. The
question of fuel, it may be remarked, has a social, an antiquarian,
and a chemical interest. In the first place, the inquiry whether or
not our supplies of coal will hold out for say the next hundred
thousand years, or for a much more limited period only, has been very
often discussed by sociologists and by geological authorities.
Again, it is clear that as man advances in the practice of civilized
arts, his dependence upon fuel becomes of more and more intimate
character. He not merely demands fire wherewith to cook his food, and
to raise his own temperature or that of his dwelling, but requires
fuel for the thousand and one manufacturing operations in which he is
perpetually engaged. It is obvious that without fuel civilized life
would practically come to an end. We cannot take the shortest journey
by rail or steamboat without a tacit dependence upon a fuel supply;
and the failure of this supply would therefore mean and imply the
extinction of all the comforts and conveniences on which we are
accustomed to rely as aids to easy living in these latter days. Again,
socially regarded, man is the only animal that practices the
fire-making habit. Even the highest apes, who will sit round the fire
which a traveler has just left, and enjoy the heat, do not appear to
have developed any sense or idea of keeping up the fire by casting
fresh fuel upon it. It seems fairly certain, then, that we may define
man as being a "fuel-employing animal," and in so doing be within the
bounds of certitude. He may be, and often is, approached by other
animals in respect of many of his arts and practices. Birds weave nest
materials, ants make--and maul--slaves, beavers build dams, and other
animals show the germs and beginnings of human contrivances for aiding
the processes of life, but as yet no animal save man lights and
maintains a fire. That the fire-making habit must have dawned very
early in human history appears to be proved by the finding of ashes
and other evidences of the presence of fire among the remains and
traces of primitive man.
All we know, also, concerning the history of savage tribes teaches us
that humanity is skillful, even in very rude stages of its progress,
in the making of fire. The contrivances for obtaining fire are many
and curious in savage life, while, once attained, this art seems to
have not only formed a constant accompaniment but probably also a
determining cause in the evolution of civilization. Wood, the fat of
animals, and even the oils expressed from plants, probably all became
known to man as convenient sources of fuel in prehistoric times. From
the incineration of wood to the use of peat and coal would prove an
easy stage in the advance toward present day practices, and with the
attainment of coal as a fuel the first great era in man's fire-making
habits may be said to end.
Beyond the coal stage, however, lies the more or less distinctively
modern one of the utilization of gas and oil for fuel. The existence
of great natural centers, or underground stores, of gas and oil is
probably no new fact. We read in the histories of classic chroniclers
of the blazing gases which were wont to issue from the earth, and to
inspire feelings of superstitious awe in the minds of beholders. Only
within a few years, however, have geologists been able to tell us much
or anything regarding these reservoirs of natural fuel which have
become famous in America and in the Russian province of Baku.
For example, it is now known that three products--gas, oil, and salt
or brine--lie within natural receptacles formed by the rock strata in
the order of their weight. This law, as has well been said, forms the
foundation of all successful boring experiments, and the search for
natural fuel, therefore, becomes as easy and as reliable a duty as
that for artesian water or for coal. The great oil fever of the West
was attended at first, as Professor M'Gee tells us, with much waste of
the product. Wells were sunk everywhere, and the oil overflowed the
land, tainting the rivers, poisoning the air, and often driving out
the prospectors from the field of discovery. In Baku accidents and
catastrophes have, similarly, been of frequent occurrence. We read of
petroleum flowing from the ground in jets 200 feet high, and as thick
as a man's body; we learn how it swept away the huge cranes and other
machinery, and how, as it flowed away from the orifices, its course
was marked by the formation of rivers of oil many miles in length.
In America the pressure of rock gas has burst open stills weighing
over a ton, and has rushed through huge iron tanks and split open the
pipes wherewith it was sought to control its progress. The roar of
this great stream of natural gas was heard for miles around as it
escaped from the outlet, and when it was ignited the pillar of flame
illumined the surrounding country over a radius extending in some
cases to forty miles. It is clear that man having tapped the earth's
stores of natural fuel, stood in danger of having unloosed a monster
whose power he seemed unable to control. Yet, as the sequel will show,
science has been able to tackle with success the problems of mastering
the force and of utilizing the energy which are thus locked up within
the crust of the globe.
As regards the chemistry of rock gas, we may remark in the first place
that this natural product ranks usually as light carbureted hydrogen
gas. In this respect it is not unlike the marsh gas with which
everyone is familiar, which is found bubbling up from swamps and
morasses, and which constitutes the "will o' the wisp" of romance. In
rock gas, marsh gas itself is actually found in the proportion of
about 93 per cent. The composition of marsh gas is very simple. It
consists of the two elements carbon and hydrogen united in certain
proportions, indicated chemically by the symbol CH4. We find, in fact,
that rock gas possesses a close relationship, chemically speaking,
with many familiar carbon compounds, and of these latter, petroleum
itself, asphaltum, coal, jet, graphite or plumbago, and even the
diamond itself--which is only crystallized carbon after all--are
excellent examples.
The differences between these substances really consist in the degree
of fixing of the carbon or solid portion of the product, as it were,
which exists. Thus in coal and jet the carbon is of stable character,
such as we might expect to result from the slow decomposition of
vegetable matter, and the products of this action are not volatile or
liable to be suddenly dissociated or broken up. On the other hand,
when we deal with the _hydrocarbons_ as they are called, in the shape
of rock gas, naphtha, petroleum, tar, asphaltum, and similar
substances, we see how the carbon has become subordinated to the
hydrogen part of the compounds, with the result of rendering them more
or less unstable in their character. As Professor M'Gee has shown us,
there is in truth a graduated series leading us from the marsh gas and
rock gas as the lightest members of this class of compounds onward
through the semi-gaseous naphtha to the fluid petroleum, the
semi-fluid tar, the solid asphaltum, and the rigid and brittle
substance known as albertite, with other and allied products. Having
said so much regarding the chemistry of the fuels of the future, we
may now pass to consider their geological record. A somewhat curious
distribution awaits the man of science in this latter respect. Most
readers are aware that the geologists are accustomed to classify
rocks, according to their relative age, into three great groups, known
respectively as the primary, secondary, and tertiary periods. In the
secondary period we do not appear to meet with the fuels of the
future, but as far back as the Devonian or old Red Sandstone period,
and in the still older Silurian rocks, stores of gas and petroleum
abound. In the latest or tertiary period, again, we come upon nearly
all the forms of fuels we have already specified.
The meaning of this geological distribution of the fuels is entirely
fortuitous. Dr. M'Gee tells us that as their formation depended on
local conditions (such as plant growth), and as we have no means of
judging why such local conditions occurred within any given area, so
must we regard the existence of fuel products in particular regions as
beyond explanation. Of one point, however, we are well assured, namely
that the volume of the fuels of the future is developed in an inverse
proportion to their geological age. The proportionate volume, as it
has been expressed, diminishes progressively as the geological scale
is descended. Again, the weight of the fuels varies directly with
their age; for it is in the older formation of any series that we come
upon the oils and tars and asphaltum, while the marsh gas exists in
later and more recently formed deposits. Further geological research
shows us that the American gas fields exist each as an inverted trough
or dome, a conformation due, of course, to the bending and twisting of
the rocks by the great underground heat forces of the world. The
porous part of the dome may be sandstone or limestone, and above this
portion lie shales, which are the opposite of porous in texture. The
dome, further, contains gas above, naphtha in the middle, and
petroleum below, while last of all comes water, which is usually very
salt. In the Indiana field, however, we are told that the oils lie
near the springing or foundation of the arch of the dome, and at its
crown gas exists, and overlies brine.
A very important inquiry, in relation to the statement that upon the
products whose composition and history have just been described the
fuel supply of the future will depend, consists in the question of the
extent and duration of these natural gas and oil reservoirs. If we are
beginning to look forward to a time when our coal supply will have
been worked out, it behooves us to ask whether or not the supply of
natural gas and oil is practically illimitable. The geologist will be
able to give the coming man some degree of comfort on this point, by
informing him that there seems to be no limit to the formation of the
fuel of the future.
Natural gas is being manufactured to-day by nature on a big scale.
Wherever plant material has been entombed in the rock formations, and
wherever its decomposition proceeds, as proceed it must, there natural
gas is being made. So that with the prospect of coal becoming as rare
as the dodo itself, the world, we are told by scientists, may still
regard with complacency the failure of our ordinary carbon supply. The
natural gases and oils of the world will provide the human race with
combustible material for untold ages--such at least is the opinion of
those who are best informed on the subject. For one thing, we are
reminded that gas is found to be the most convenient and most
economical of fuels. Rock gas is being utilized abroad even now in
manufacturing processes. Dr. M'Gee says that even if the natural
supply of rock gas were exhausted to-morrow, manufacturers of glass,
certain grades of iron, and other products would substitute an
artificial gas for the natural product rather than return to coal. He
adds that "enormous waste would thereby be prevented, the gas by which
the air of whole counties in coke-burning regions is contaminated
would be utilized, and the carbon of the dense smoke clouds by which
manufacturing cities are overshadowed would be turned to good
account." So that, as regards the latter point, even Mr. Ruskin with
his horror of the black smoke of to-day and of the disfigurement of
sky and air might become a warm ally of the fuel of the future. The
chemist in his laudation of rock gas and allied products is only
re-echoing, when all is said and done, the modern eulogy pronounced on
ordinary coal gas as a cooking and heating medium.
We are within the mark when we say that the past five years alone have
witnessed a wonderful extension in the use of gas in the kitchen and
elsewhere. It would be singular, indeed, if we should happen to be
already anticipating the fuel of the future by such a practice.
Whether or not this is the case, it is at least satisfactory for
mankind to know that the mother earth will not fail him when he comes
to demand a substitute for coal. I may be too early even to think of
the day of extinction; but we may regard that evil day with
complacency in face of the stores of fuel husbanded for us within the
rock foundations of our planet.--_Glasgow Herald._
* * * * *
PORTABLE ELECTRIC LIGHT.
The famous house of MM. Sautter, Lemonnier & Co. takes a conspicuous
part in the Paris exhibition, and from the wide range of its
specialties exhibits largely in three important branches of industry:
mechanics, electricity, and the optics of lighthouses and projectors.
In these three branches MM. Sautter, Lemonnier & Co. occupy a leading
position in all parts of the world.
The invention of the aplanetic projector, due to Col. Mangin, was a
clever means of overcoming difficulties, practically insurmountable,
that were inseparable from the construction of parabolic mirrors; this
contributed chiefly to the success of MM. Sautter, Lemonnier & Co. in
this direction. The firm has produced more than 1,500 of these
apparatus, representing a value of nearly £500,000, for the French and
other governments.
Besides the great projector, which forms the central and crowning
object of the exhibit of MM. Sautter, Lemonnier & Co. in the machinery
hall, the firm exhibits a projector 90 centimeters in diameter mounted
on a crane traveling on wheels, in the pavilion of the War Department.
The lamp used for this apparatus has a luminous value of 6,000
carcels, with a current of 100 amperes; the amplifying power of the
mirror is 2,025, which gives an intensity of ten millions to twelve
millions of carcels to the beam.
Projectors used for field work are mounted on a portable carriage,
which also contains the electric generator and the motor driving it.
[Illustration: MILITARY PORTABLE ELECTRIC LIGHT AT THE PARIS
EXHIBITION.]
It consists of a tubular boiler (Dion, Bouton & Trepardoux system).
This generator is easily taken to pieces, cleaned, and repaired, and
steam can be raised to working pressure in 20 minutes. The mechanical
and electrical part of the apparatus consists of a Parsons
turbo-motor, of which MM. Sautter, Lemonnier & Co. possess the license
in France for application to military and naval purposes. The speed of
the motor is 9,000 revolutions per minute, and the dynamo is driven
direct from it; at this speed it gives a current of 100 amperes with
and from 55 to 70 volts; the intensity of the light is from 5,500 to
6,000 carcels. The carriage upon which the whole of this apparatus is
mounted is carried on four wheels, made of wood with gun metal
mountings. These are more easy to repair when in service than if they
were wholly of iron. The weight of the carriage is three
tons.--_Engineering._
* * * * *
ELECTRIC MOTOR FOR ALTERNATING CURRENTS.
Prof. Galileo Ferraris, of Turin, who has carefully studied
alternating currents and secondary transformers, has constructed a
little motor based upon an entirely new principle, which is as
follows: If we take two inductive fields developed by two bobbins, the
axes of which cut each other at right angles, and a pole placed at the
vertex of the angle, this pole will be subjected to the simultaneous
action of the two bobbins, and the resultant of the magnetic actions
will be represented in magnitude and direction by the diagonal of the
parallelogram, two consecutive sides of which have for their length
the intensity of the two fields, and for their direction the axes of
the two bobbins.
If into each of these bobbins we send alternating currents having
between one bobbin and the other a difference of phase of 90°, the
extremity of the resultant will describe a circle having for its
center the vertex of the right angle.
If, instead of a fixed pole, we use a metal cylinder movable on its
axis, we shall obtain a continuous rotatory motion of this part, and
the direction of the movement will change when we interchange the
difference of phase in the exciting currents. This rotatory movement
is not due to the Foucault currents, for the metal cylinder may
consist of plates of iron insulated from each other.
In order to realize the production of these fields, several means can
be employed: The current is sent from an alternating current machine
into the primary circuit of a transformer and thence into one of the
bobbins, the other being supplied by means of the secondary current of
the transformer. A resistance introduced into the circuit will produce
the required difference of phase, and the equality of the intensities
of the fields will be obtained by multiplying the number of turns of
the secondary wire on the bobbin. Moreover, the two bobbins may be
supplied by the secondary current of a transformer by producing the
difference of phase, as in the first case.
In the motor constructed by Prof. Ferraris the armature consisted of a
copper cylinder measuring 7 centimeters in diameter and 15 centimeters
in length, movable on its axis. The inductors were formed of two
groups of two bobbins. The bobbins which branched off from the primary
circuit of a Gaulard transformer, and were connected in series,
comprised 196 spirals with a resistance of 13 ohms; the bobbins
comprising the secondary circuit were coupled in parallel, and had 504
spirals with 3.43 ohms resistance. In order to produce the difference
of phase, a resistance of 17 ohms was introduced into the second
circuit, when the dynamo produced a current of 9 amperes with 80
inversions per second. Under these conditions the available work
measured on the axis of the motor was found for different speeds:
Revolutions per minute: 262--400--546--650--722--770. Watts measured
at the brake: 1.32--2.12--2.55--2.77--2.55--2.40. The maximum
rendering corresponds to a speed of rotation of 650 revolutions, and
Prof. Ferraris attributes the loss of work for higher speeds to the
vibrations to which the machine is exposed. At present the apparatus
is but a laboratory one.--_Bulletin International de l'Electricite._
* * * * *
THE ELECTRIC AGE.
By CHARLES CARLETON COFFIN.
The application of electricity for our convenience and comfort is one
of the marvels of the age. Never in the history of the world has there
been so rapid a development of an occult science. Prior to 1819 very
little was known in regard to magnetism and electricity. During that
year Oersted discovered that an electric current would deflect a
magnetic needle, thus showing that there was some relationship between
electric and magnetic force. A few months later, Arago and Sir Humphry
Davy, independently of each other, discovered that by coiling a wire
around a piece of iron, and passing an electric current through it,
the iron would possess for the time being all the properties of a
magnet. In 1825 William Sturgeon, of London, bent a piece of wire in
the form of the letter U, wound a second wire around it, and, upon
connecting it with a galvanic battery, discovered that the first wire
became magnetic, but lost its magnetic property the moment the battery
was disconnected. The idea of a telegraphic signal came to him, but
the electric impulse, through his rude apparatus, faded out at a
distance of fifty feet. In 1830 Prof. Joseph Henry, of this country,
constructed a line of wire, one and a half miles in length, and sent a
current of electricity through it, ringing a bell at the farther end.
The following year Professor Faraday discovered magnetic induction.
This, in brief, is the genesis of magnetic electricity, which is the
basis of all that has been accomplished in electrical science.
The first advance after these discoveries was in the development of
the electric telegraph--the discovery in 1837, by the philosopher
Steinhill, that the earth could serve as a conductor, thus requiring
but one wire in the employment of an electric current. Simultaneously
came Morse's invention of the mechanism for the telegraph in 1844,
foreshadowed by Henry in the ringing of bells, thus transmitting
intelligence by sound. Four years later, in 1848, Prof. M. G. Farmer,
still living in Eliot, Me., attached an electro-magnet to clockwork
for the striking of bells to give an alarm of fire. The same idea came
to William F. Channing. The mechanism, constructed simply to
illustrate the idea by Professor Farmer, was placed upon the roof of
the Court House in Boston, and connected with the telegraph wire
leading to New York, and an alarm rung by the operator in that city.
The application of electricity for giving definite information to
firemen was first made in Boston, and it was my privilege to give the
first alarm on the afternoon of April 12, 1852.
At the close of the last century, Benjamin Thompson, born in Woburn,
Mass., known to the world as Count Rumford, was in the workshop of the
military arsenal of the King of Bavaria in Munich, superintending the
boring of a cannon. The machinery was worked by two horses. He was
surprised at the amount of heat which was generated, for when he threw
the borings into a tumbler filled with cold water, it was set to
boiling, greatly to the astonishment of the workmen. Whence came the
heat? What was heat? The old philosopher said that it was an element.
By experiment he discovered that a horse working two hours and twenty
minutes with the boring machinery would heat nineteen pounds of water
to the boiling point. He traced the heat to the horse, but with all
his acumen he did not go on with the induction to the hay and oats, to
the earth, the sunshine and rain, and so get back to the sun. One
hundred years ago there was no chemical science worthy of the name, no
knowledge of the constitution of plants or the properties of light and
heat. The old philosophers considered light and heat to be fluids,
which passed out of substances when they were too full. Count Rumford
showed that motion was convertible into heat, but did not trace the
motion to its source, so far as we know, in the sun.
It is only forty-six years since Professor Joule first demonstrated
the mutual relations of all the manifestations of nature's energy.
Thirty-nine years only have passed since he announced the great law of
the convertibility of force. He constructed a miniature churn which
held one pound of water, and connected the revolving paddle of the
churn with a wheel moved by a pound weight, wound up the weight, and
set the paddle in motion. A thermometer detected the change of
temperature and a graduated scale marked the distance traversed by the
descending weight. Repeated experiments showed that a pound weight
falling 772 feet would raise the temperature of water one degree, and
that this was an unvarying law. This was transferring gravitation to
heat, and the law held good when applied to electricity, magnetism,
and chemical affinity, leading to the conclusion that they were
severally manifestations of one universal power.--_Congregationalist._
* * * * *
EARLY ELECTRIC LIGHTING.
The opening of the new station of the Electric Lighting Co., of Salem,
Mass., was recently celebrated with appropriate festivities.
Among the letters of regret from those unable to attend the opening
was the following from Prof. Moses G. Farmer:
"ELIOT, Me., Aug. 5, 1889.
"_To the Salem Electric Lighting Company, Charles H. Price,
President_:
"GENTLEMEN: It would give me great pleasure to accept your kind
invitation to be present at the opening of your new station in Salem
on the 8th of this present August.
"It is now thirty years since the first dwelling house in Salem was
lighted by electricity. That little obscure dwelling, 11 Pearl Street,
formerly owned by 'Pa' Webb, had the honor to be illuminated by the
effulgent electric beam during every evening of July, 1859, as some of
your honored residents, perhaps, well remember. Mr. George D. Phippen
can doubtless testify to one or more evenings; Mr. Wm. H. Mendell, of
Boston, can also add his testimony; dozens of others could also do the
same, had not some of them already passed to the 'great beyond,' among
whom I well recollect the interest taken by the late and honored Henry
L. Williams, Mr. J. G. Felt, and I do not know how many others. I well
remember reading some of the very finest print standing with my back
to the front wall and reading by the light of a 32 candle power lamp
on the northernmost end of the mantel piece in the parlor; very
possibly the hole in which the lamp was fastened remains to this day.
In a little closet in the rear sleeping room was a switch which could
be turned in one direction and give a beautiful glow light, while if
turned in the other direction, it instantly gave as beautiful a dark.
My then 12 year old daughter used to surprise and please her visitors
by suddenly turning on and off the 'glim.' It is not well to despise
the day of small things, for although the dynamo had not at that date
put in an appearance, and though I used thirty-six Smee cells of six
gallons capacity each, yet I demonstrated then and there that the
incandescent electric light was a possibility, and although I
innocently remarked to the late Samuel W. Bates, of Boston, who with
his partner, Mr. Chauncey Smith, furnished so generously in the
interest of science, not wholly without hope of return, the funds for
the experiment, that it 'did not take much zinc,' and though Mr. Bates
as naively replied, 'I notice that it takes some silver, though,'
still it was then and there heralded as the coming grand illuminant
for the dwelling. I am thankful to have lived to see my predictions
partly fulfilled.
"During the early fifties I published a statement something like this:
'One pound of coal will furnish gas enough to maintain a candle light
for fifteen hours. One pound of gas (the product of five pounds of
coal) will, in a good fishtail gas burner, furnish one candle light
for seventy-five hours. One pound of coal burned in a good furnace,
under a good boiler, driving a good steam engine, turning a good
magneto-electric machine, will give a candle light for one thousand
hours. But if all the energy locked up in one pound of pure carbon
could be wholly converted into light, it would maintain one candle
light for more than one and a half years.'
"So, gentlemen, _nil desperandum_; there is still room for
improvement. Let your motto be 'Excelsior.' Possibly you may have
already extracted from one-fifteenth to one-twelfth of the energy
stored in the pound of carbon, but hardly more. Go on, go on, and
bring it so cheap as to reach the humblest dwelling when you shall
celebrate the centennial of the opening of your new station.
"I do most sincerely regret that I cannot be with you in the flesh. I
am, like Ixion of old, confined to a wheel (chair in my case), cannot
walk, cannot even stand; hence, owing to the impairment of my
understanding (???), I must wish you all the enjoyments of the
evening, and gladly content myself that you have made so much
possible.
"Very truly yours, MOSES G. FARMER."
* * * * *
THE MODERN THEORY OF LIGHT.[1]
[Footnote 1: Being the general substance of a lecture to the
Ashmolean Society in the University of Oxford, on Monday, June
3, 1889. [Reprinted from the _Liverpool University College
Magazine_.]]
By Prof. OLIVER LODGE.
To persons occupied in other branches of learning, and not directly
engaged in the study of physical science, some rumor must probably
have traveled of the stir and activity manifest at the present time
among the votaries of that department of knowledge.
It may serve a useful purpose if I try and explain to outsiders what
this stir is mainly about, and why it exists. There is a proximate and
there is an ultimate cause. The proximate cause is certain experiments
exhibiting in a marked and easily recognizable way the already
theoretically predicted connection between electricity and light. The
ultimate cause is that we begin to feel inklings and foretastes of
theories, wider than that of gravitation, more fundamental than any
theories which have yet been advanced; theories which if successfully
worked out will carry the banner of physical science far into the dark
continent of metaphysics, and will illuminate with a clear philosophy
much that is at present only dimly guessed. More explicitly, we begin
to perceive chinks of insight into the natures of electricity, of
ether, of elasticity, and even of matter itself. We begin to have a
kinetic theory of the physical universe.
We are living, not in a Newtonian, but at the beginning of a perhaps
still greater Thomsonian era. Greater, not because any one man is
probably greater than Newton,[2] but because of the stupendousness of
the problems now waiting to be solved. There are a dozen men of great
magnitude, either now living or but recently deceased, to whom what we
now know toward these generalizations is in some measure due, and the
epoch of complete development may hardly be seen by those now alive.
It is proverbially rash to attempt prediction, but it seems to me that
it may well take a period of fifty years for these great strides to be
fully accomplished. If it does, and if progress goes on at anything
like its present rate, the aspect of physical science bequeathed to
the latter half of the twentieth century will indeed excite
admiration, and when the populace are sufficiently educated to
appreciate it, will form a worthy theme for poetry, for oratorios, and
for great works of art.
[Footnote 2: Though, indeed, a century hence it may be premature
to offer an opinion on such a point.]
To attempt to give any idea of the drift of progress in all the
directions which I have hastily mentioned, to attempt to explain the
beginnings of the theories of elasticity and of matter, would take too
long, and might only result in confusion. I will limit myself chiefly
to giving some notion of what we have gained in knowledge concerning
electricity, ether, and light. Even that is far too much. I find I
must confine myself principally to light, and only treat of the others
as incidental to that.
For now well nigh a century we have had a wave theory of light; and a
wave theory of light is quite certainly true. It is directly
demonstrable that light consists of waves of some kind or other, and
that these waves travel at a certain well-known velocity, seven times
the circumference of the earth per second, taking eight minutes on the
journey from the sun to the earth. This propagation in time of an
undulatory disturbance necessarily involves a medium. If waves setting
out from the sun exist in space eight minutes before striking our
eyes, there must necessarily be in space some medium in which they
exist and which conveys them. Waves we cannot have unless they be
waves in something.
No ordinary medium is competent to transmit waves at anything like the
speed of light; hence the luminiferous medium must be a special kind
of substance, and it is called the ether. The _luminiferous_ ether it
used to be called, because the conveyance of light was all it was then
known to be capable of; but now that it is known to do a variety of
other things also, the qualifying adjective may be dropped.
Wave motion in ether, light certainly is; but what does one mean by
the term wave? The popular notion is, I suppose, of something heaving
up and down, or, perhaps, of something breaking on the shore in which
it is possible to bathe. But if you ask a mathematician what he means
by a wave, he will probably reply that the simplest wave is
y = a sin (p t - n x),
and he might possibly refuse to give any other answer.
And in refusing to give any other answer than this, or its equivalent
in ordinary words, he is entirely justified; that is what is meant by
the term wave, and nothing less general would be all-inclusive.
Translated into ordinary English the phrase signifies "a disturbance
periodic both in space and time." Anything thus doubly periodic is a
wave; and all waves, whether in air as sound waves, or in ether as
light waves, or on the surface of water as ocean waves, are
comprehended in the definition.
What properties are essential to a medium capable of transmitting wave
motion? Roughly we may say two--_elasticity_ and _inertia_. Elasticity
in some form, or some equivalent of it, in order to be able to store
up energy and effect recoil; inertia, in order to enable the disturbed
substance to overshoot the mark and oscillate beyond its place of
equilibrium to and fro. Any medium possessing these two properties can
transmit waves, and unless a medium possesses these properties in some
form or other, or some equivalent for them, it may be said with
moderate security to be incompetent to transmit waves. But if we make
this latter statement, one must be prepared to extend to the terms
elasticity and inertia their very largest and broadest signification,
so as to include any possible kind of restoring force and any possible
kind of persistence of motion respectively.
These matters may be illustrated in many ways, but perhaps a simple
loaded lath or spring in a vise will serve well enough. Pull aside one
end, and its elasticity tends to make it recoil; let it go, and its
inertia causes it to overshoot its normal position; both causes
together cause it to swing to and fro till its energy is exhausted. A
regular series of such springs at equal intervals in space, set going
at regular intervals of time one after the other, gives you at once a
wave motion and appearance which the most casual observer must
recognize as such. A series of pendulums will do just as well. Any
wave-transmitting medium must similarly possess some form of
elasticity and of inertia.
But now proceed to ask what is this ether which in the case of light
is thus vibrating? What corresponds to the elastic displacement and
recoil of the spring or pendulum? What corresponds to the inertia
whereby it overshoots its mark? Do we know these properties in the
ether in any other way?
The answer, given first by Clerk Maxwell, and now reiterated and
insisted on by experiments performed in every important laboratory in
the world, is:
The elastic displacement corresponds to electrostatic charge (roughly
speaking, to electricity).
The inertia corresponds to magnetism.
This is the basis of the modern electro-magnetic theory of light. Now
let me illustrate electrically how this can be.
The old and familiar operation of charging a Leyden jar--the storing
up of energy in a strained dielectric, any electrostatic charging
whatever--is quite analogous to the drawing aside of our flexible
spring. It is making use of the elasticity of the ether to produce a
tendency to recoil. Letting go the spring is analogous to permitting a
discharge of the jar--permitting the strained dielectric to recover
itself, the electrostatic disturbance to subside.
In nearly all the experiments of electrostatics, ethereal elasticity
is manifest.
Next consider inertia. How would one illustrate the fact that water,
for instance, possesses inertia--the power of persisting in motion
against obstacles--the power of possessing kinetic energy? The most
direct way would be to take a stream of water and try suddenly to stop
it. Open a water tap freely and then suddenly shut it. The impetus or
momentum of the stopped water makes itself manifest by a violent shock
to the pipe, with which everybody must be familiar. The momentum of
water is utilized by engineers in the "water ram."
A precisely analogous experiment in electricity is what Faraday called
"the extra current." Send a current through a coil of wire round a
piece of iron, or take any other arrangement for developing powerful
magnetism, and then suddenly stop the current by breaking the circuit.
A violent flash occurs if the stoppage is sudden enough, a flash which
means the bursting of the insulating air partition by the accumulated
electro-magnetic momentum.
Briefly, we may say that nearly all electro-magnetic experiments
illustrate the fact of ethereal inertia.
Now return to consider what happens when a charged conductor (say a
Leyden jar) is discharged. The recoil of the strained dielectric
causes a current, the inertia of this current causes it to overshoot
the mark, and for an instant the charge of the jar is reversed; the
current now flows backward and charges the jar up as at first; back
again flows the current, and so on, charging and reversing the charge
with rapid oscillations until the energy is all dissipated into heat.
The operation is precisely analogous to the release of a strained
spring or to the plucking of a stretched string.
But the discharging body thus thrown into strong electrical vibration
is embedded in the all-pervading ether, and we have just seen that the
ether possesses the two properties requisite for the generation and
transmission of waves--viz., elasticity and inertia or density; hence,
just as a tuning fork vibrating in air excites aerial waves or sound,
so a discharging Leyden jar in ether excites ethereal waves or light.
Ethereal waves can therefore be actually produced by direct electrical
means. I discharge here a jar, and the room is for an instant filled
with light. With light, I say, though you can see nothing. You can see
and hear the spark indeed--but that is a mere secondary disturbance we
can for the present ignore--I do not mean any secondary disturbance. I
mean the true ethereal waves emitted by the electric oscillation going
on in the neighborhood of this recoiling dielectric. You pull aside
the prong of a tuning fork and let it go; vibration follows and sound
is produced. You charge a Leyden jar and let it discharge; vibration
follows and light is excited.
It is light just as good as any other light. It travels at the same
pace, it is reflected and refracted according to the same laws; every
experiment known to optics can be performed with this ethereal
radiation electrically produced, and yet you cannot see it. Why not?
For no fault of the light; the fault (if there be a fault) is in the
eye. The retina is incompetent to respond to these vibrations--they
are too slow. The vibrations set up when this large jar is discharged
are from a hundred thousand to a million per second, but that is too
slow for the retina. It responds only to vibrations between 4,000
billions and 7,000 billions per second. The vibrations are too quick
for the ear, which responds only to vibrations between 40 and 40,000
per second. Between the highest audible and the lowest visible
vibrations there has been hitherto a great gap, which these electric
oscillations go far to fill up. There has been a great gap simply
because we have no intermediate sense organ to detect rates of
vibration between 40,000 and 4,000,000,000,000,000 per second. It was,
therefore, an unexplored territory. Waves have been there all the time
in any quantity, but we have not thought about them nor attended to
them.
It happens that I have myself succeeded in getting electric
oscillations so slow as to be audible. The lowest I have got at
present are 125 per second, and for some way above this the sparks
emit a musical note; but no one has yet succeeded in directly making
electric oscillations which are visible, though indirectly every one
does it when they light a candle.
Here, however, is an electric oscillator, which vibrates 300 million
times a second, and emits ethereal waves a yard long. The whole range
of vibrations between musical tones and some thousand million per
second is now filled up.
These electro-magnetic waves have long been known on the side of
theory, but interest in them has been immensely quickened by the
discovery of a receiver or detector for them. The great though simple
discovery by Hertz of an "electric eye," as Sir W. Thomson calls it,
makes experiments on these waves for the first time easy or even
possible. We have now a sort of artificial sense organ for their
appreciation--an electric arrangement which can virtually "see" these
intermediate rates of vibration.
The Hertz receiver is the simplest thing in the world--nothing but a
bit of wire or a pair of bits of wire adjusted so that when immersed
in strong electric radiation they give minute sparks across a
microscopic air gap.
The receiver I have here is adapted for the yard-long waves emitted
from this small oscillator; but for the far longer waves emitted by a
discharging Leyden jar an excellent receiver is a gilt wall paper or
other interrupted metallic surface. The waves falling upon the
metallic surface are reflected, and in the act of reflection excite
electric currents, which cause sparks. Similarly, gigantic solar waves
may produce auroræ; and minute waves from a candle do electrically
disturb the retina.
The smaller waves are, however, far the most interesting and the most
tractable to ordinary optical experiments. From a small oscillator,
which may be a couple of small cylinders kept sparking into each other
end to end by an induction coil, waves are emitted on which all manner
of optical experiments can be performed.
They can be reflected by plain sheets of metal, concentrated by
parabolic reflectors, refracted by prisms, concentrated by lenses. I
have at the college a large lens of pitch, weighing over three
hundredweight, for concentrating them to a focus. They can be made to
show the phenomenon of interference, and thus have their wave length
accurately measured. They are stopped by all conductors and
transmitted by all insulators. Metals are opaque, but even imperfect
insulators such as wood or stone are strikingly transparent, and waves
may be received in one room from a source in another, the door between
the two being shut.
The real nature of metallic opacity and of transparency has long been
clear in Maxwell's theory of light, and these electrically produced
waves only illustrate and bring home the well known facts. The
experiments of Hertz are in fact the apotheosis of that theory.
Thus, then, in every way Maxwell's 1865 brilliant perception of the
real nature of light is abundantly justified; and for the first time
we have a true theory of light, no longer based upon analogy with
sound, nor upon a hypothetical jelly or elastic solid.
Light is an electro-magnetic disturbance of the ether. Optics is a
branch of electricity. Outstanding problems in optics are being
rapidly solved now that we have the means of definitely exciting light
with a full perception of what we are doing and of the precise mode of
its vibration.
It remains to find out how to shorten down the waves--to hurry up the
vibration until the light becomes visible. Nothing is wanted but
quicker modes of vibrations. Smaller oscillators must be used--very
much smaller--oscillators not much bigger than molecules. In all
probability--one may almost say certainly--ordinary light is the
result of electric oscillation in the molecules of hot bodies, or
sometimes of bodies not hot--as in the phenomenon of phosphorescence.
The direct generation of _visible_ light by electric means, so soon as
we have learnt how to attain the necessary frequency of vibration,
will have most important practical consequences.
Speaking in this university, it is happily quite unnecessary for me to
bespeak interest in a subject by any reference to possible practical
applications. But any practical application of what I have dealt with
this evening is apparently so far distant as to be free from any
sordid gloss of competition and company promotion, and is interesting
in itself as a matter of pure science.
For consider our present methods of making artificial light; they are
both wasteful and ineffective.
We want a certain range of oscillation, between 7,000 and 4,000
billion vibrations per second; no other is useful to us, because no
other has any effect upon our retina; but we do not know how to
produce vibrations of this rate. We can produce a definite vibration
of one or two hundred or thousand per second; in other words, we can
excite a pure tone of definite pitch; and we can demand any desired
range of such tones continuously by means of bellows and a keyboard.
We can also (though the fact is less well known) excite momentarily
definite ethereal vibrations of some million per second, as I have
explained at length; but we do not at present seem to know how to
maintain this rate quite continuously. To get much faster rates of
vibration than this we have to fall back upon atoms. We know how to
make atoms vibrate; it is done by what we call "heating" the
substance, and if we could deal with individual atoms unhampered by
others, it is possible that we might get a pure and simple mode of
vibration from them. It is possible, but unlikely; for atoms, even
when isolated, have a multitude of modes of vibration special to
themselves, of which only a few are of practical use to us, and we do
not know how to excite some without also the others. However, we do
not at present even deal with individual atoms; we treat them crowded
together in a compact mass, so that their modes of vibration are
really infinite.
We take a lump of matter, say a carbon filament or a piece of
quicklime, and by raising its temperature we impress upon its atoms
higher and higher modes of vibration, not transmuting the lower into
the higher, but superposing the higher upon the lower, until at length
we get such rates of vibration as our retina is constructed for, and
we are satisfied. But how wasteful and indirect and empirical is the
process. We want a small range of rapid vibrations, and we know no
better than to make the whole series leading up to them. It is as
though, in order to sound some little shrill octave of pipes in an
organ, we are obliged to depress every key and every pedal, and to
blow a young hurricane.
I have purposely selected as examples the more perfect methods of
obtaining artificial light, wherein the waste radiation is only useless
and not noxious. But the old-fashioned plan was cruder even than this;
it consisted simply in setting something burning; whereby not the fuel
but the air was consumed, whereby also a most powerful radiation was
produced, in the waste waves of which we were content to sit stewing,
for the sake of the minute--almost infinitesimal--fraction of it which
enabled us to see.
Every one knows now, however, that combustion is not a pleasant or
healthy mode of obtaining light; but every one does not realize that
neither is incandescence a satisfactory and unwasteful method which is
likely to be practiced for more than a few decades, or perhaps a
century.
Look at the furnaces and boilers of a great steam engine driving a
group of dynamos, and estimate the energy expended; and then look at
the incandescent filaments of the lamps excited by them, and estimate
how much of their radiated energy is of real service to the eye. It
will be as the energy of a pitch pipe to an entire orchestra.
It is not too much to say that a boy turning a handle could, if his
energy were properly directed, produce quite as much real light as is
produced by all this mass of mechanism and consumption of material.
There might, perhaps, be something contrary to the laws of nature in
thus hoping to get and utilize some specific kind of radiation without
the rest, but Lord Rayleigh has shown in a short communication to the
British Association at York that it is not so, and that, therefore, we
have a right to try to do it.
We do not yet know how, it is true, but it is one of the things we
have got to learn.
Any one looking at a common glow-worm must be struck with the fact
that not by ordinary combustion, nor yet on the steam engine and
dynamo principle, is that easy light produced. Very little waste
radiation is there from phosphorescent things in general. Light of the
kind able to affect the retina is directly emitted; and for this, for
even a large supply of this, a modicum of energy suffices.
Solar radiation consists of waves of all sizes, it is true; but then
solar radiation has innumerable things to do besides making things
visible. The whole of its energy is useful. In artificial lighting
nothing but light is desired; when heat is wanted it is best obtained
separately by combustion. And so soon as we clearly recognize that
light is an electric vibration, so soon shall we begin to beat about
for some mode of exciting and maintaining an electrical vibration of
any required degree of rapidity. When this has been accomplished the
problem of artificial lighting will have been solved.
* * * * *
ON PURIFICATION OF AIR BY OZONE--WITH AN ACCOUNT OF A NEW METHOD.[1]
[Footnote 1: Paper read in Section C, Domestic Health, at the
Hastings Health Congress, on Friday, May 3, 1889.]
By Dr. B. W. RICHARDSON.
During the time when I was engaged in my preliminary medical
studies--for I never admit to this day of being anything less than a
medical student--the substance called ozone became the topic of much
conversation and speculation. I cannot say that ozone was a discovery
of that date, for in the early part of the century Von Marum had
observed that when electrical discharges were made through oxygen in a
glass cylinder inverted over water, the water rose in the cylinder as
if something had either been taken away from the gas, or as if the gas
itself had been condensed, and was therefore occupying a smaller
space. It had also been observed by many electricians that during a
passage of the electric spark through air or oxygen, there was a
peculiar emanation or odor which some compared to fresh sea air,
others to the air after a thunderstorm, when the sky has become very
clear, the firmament blue, and the stars, if visible, extremely
bright.
But it was not until the time, or about the time, of which I have
spoken, 1846-49, that these discovered but unexplained phenomena
received proper recognition. The distinguished physicist Schonbein
first, if I may so say, isolated the substance which yielded the
phenomena, and gave to it the name, by which it has since generally
been known, of _ozone_, which means, to emit an odor; a name, I have
always thought, not particularly happy, but which has become,
practically, so fully recognized and understood, that it would be
wrong now to disturb it.
Schonbein made ozone by the action of the electric spark on oxygen. He
collected it, he tested its chemical properties, he announced it to be
oxygen in a modified form, and he traced its action as an active
oxidizer of various substances, and especially of organic substances,
even when they were in a state of decomposition.
But Schonbein went further than this. He argued that ozone was a
natural part of the atmosphere, and that in places where there was no
decomposition, that is to say, in places away from great towns, ozone
was present. On the high tower of a cathedral in a big city he
discovered ozone; in the city, at the foot of the tower, he found no
ozone at the same time. He argued, therefore, that the ozone above was
used up in purifying the town below, and so suggested quite a new
explanation of the purification of air.
The subject was very soon taken up by English observers, and I
remember well a lecture upon it by Michael Faraday, in which that
illustrious philosopher, confirming Schonbein, stated that he had
discovered ozone freely on the Brighton Downs, and had found the
evidence of it diminishing as he approached Brighton, until it was
lost altogether in the town itself.
Such was the beginning of our knowledge of ozone, the precise nature
of which has not yet been completely made out. At the present time it
is held to be oxygen condensed. To use a chemical phrase, the molecule
of oxygen, which in the ordinary state is composed of two atoms, is
condensed, in ozone, as three atoms. By the electric spark discharged
in dry oxygen as much as 15 per cent. may, under proper conditions, be
turned into ozone. Ozone has also been found to be heavier than air.
Professor Zinno says, that compared with an equal volume of air its
density is equal to 1,658, and that it is forty-eight times heavier
than hydrogen. Heat decomposes it; at the temperature of boiling water
it begins to decompose. In water it is much less soluble than oxygen,
and indeed is practically insoluble; when made to bubble through
boiling water, it ceases to be ozone. The oxidizing power of ozone is
very much greater than that of oxygen, and, according to Saret, when
ozone is decomposed, one part of it enters into combination, the other
remains simply as oxygen.
It is remarkable that some substances, like turpentine and cinnamon,
absorb ozone and combine with it, a simple fact of much greater
importance than has ever been attached to it. I found, for instance,
that cinnamon which by exposure to the air has been made odorless and,
as it is said, "spoiled," can be made to reabsorb ozone and gain a
kind of freshness. It is certain also that some substances which are
supposed to have disinfecting properties owe what virtues they possess
to the presence of ozone.
On some grand scale ozone is formed in the air, and my former friend
and colleague, the late Dr. Moffatt, of Hawarden, with whom I wrote a
paper on "Meteorology and Disease," read before the Epidemiological
Society in 1852-53, described what he designated ozone periods of the
atmosphere, connecting these with storms. When the atmospheric
pressure is decreasing, when with that there is increasing warmth and
moisture, and when south and southwesterly winds prevail, then ozone
is active; but when the atmospheric pressure is increasing, when the
air is becoming dry and cold, and north and northeasterly winds
prevail, then the presence of ozone is less active. These facts have
also been put in another way, namely, that the maximum period of ozone
occurs when there is greatest evaporation of water from the earth, and
the minimum when there is greatest condensation of water on the earth;
a theory which tallies well with the idea that ozone is most freely
present when electricity is being produced, least present when
electricity is in smallest quantity. Mr. Buchan, reporting on the
observations of the Scottish Meteorological Society, records that
ozone is most abundant from February to June, when the average amount
is 6.0; and least from July to January, when the average is 5.7; the
maximum, 6.2, being reached in May, and the minimum, 5.3, in November.
This same excellent observer states that "ozone is more abundant on
the sea coast than inland; in the west than the east of Great Britain;
in elevated than in low situations; with southwest than with northeast
winds; in the country than in towns; and on the windward than the
leeward side of towns."
Recently a very singular hypothesis has been broached in regard to the
blue color of the firmament and ozone. It has been observed that when
a tube is filled with ozone, the light transmitted through it is of a
blue color; from which fact it is assumed that the blue color of the
sky is due to the presence of this body in the higher atmospheric
strata. The hypothesis is in entire accord with the suggestion of
Professor Dove, to which Moffatt always paid the greatest respect,
viz., that the source of ozone for the whole of the planet is
equatorial, and that the point of development of ozone is where the
terrestrial atmosphere raised to its highest altitude, at the equator,
expands out north and south in opposite directions toward the two
poles, to return to the equator over the earth as the trade winds.
It is necessary for all who would understand the applications of ozone
for any purpose, whether for bleaching purposes or pure chemical
purposes, or for medical or sanitary purposes, to understand these
preliminary facts concerning it, facts which bring me to the
particular point to which I wish to refer to-day.
In my essay describing the model city, Hygeiopolis, it was suggested
that in every town there should be a building like a gas house, in
which ozone should be made and stored, and from which it should be
dispensed to every street or house at pleasure. This suggestion was
made as the final result of observations which had been going on since
I first began to work at the subject in 1852. It occurred to me from
the moment when I first made ozone by Schonbein's method, that the
value of it in a hygienic point of view was incalculable.
To my then young and enthusiastic mind it seemed that in ozone we had
a means of stopping all putrefaction, of destroying all infectious
substances, and of actually commanding and destroying the causes which
produced the great spreading diseases; and, although increase of years
and greater experience have toned down the enthusiasm, I still believe
that here one of the most useful fields for investigation remains
almost unexplored.
In my first experiments I subjected decomposing blood to ozone, and
found that the products of decomposition were instantly destroyed, and
that the fluid was rendered odorless and sweet. I discovered that the
red corpuscles of fresh blood decomposed ozone, and that coagulated
blood underwent a degree of solution through its action. I put dead
birds and pieces of animal substances that had undergone extreme
decomposition into atmospheres containing ozone, and observed the
rapidity with which the products of decomposition were neutralized and
rendered harmless. I employed ozone medicinally, by having it inhaled
by persons who were suffering from foetor of the breath, and with
remarkable success, and I began to employ it and have employed it ever
since (that is to say, for thirty-seven years), for purposes of
disinfection and deodorization, in close rooms, closets, and the like.
I should have used it much more largely but for one circumstance,
namely, the almost impracticable difficulty of making it with
sufficient ease and in sufficient quantities to meet the necessities
of sanitary practice. We are often obstructed in this way. We know of
something exceedingly useful, but we cannot utilize it. This was the
case with ozone. I hope now that difficulty is overcome. If it is, we
shall start from this day on a new era in regard to ozone as an
instrument of sanitation.
As we have seen, ozone was originally made by charging dry oxygen or
common dry air with electricity from sparks or points. Afterward
Faraday showed that it could be made by holding a warm glass rod in
vapor of ether. Again he showed that it could be made by passing air
over bright phosphorus half immersed in water. Then Siemens modified
the electric process by inventing his well known ozone tube, which
consists of a wide glass tube coated with tinfoil on its outside, and
holding within it a smaller glass tube coated with tinfoil on its
surface. When a current of dry air or oxygen was passed in current
between these two tubes, and the electric spark from a Ruhmkorf coil
was discharged by the terminal wires connected with tinfoil surfaces,
ozone was freely produced, and this was no doubt the best method, for
by means of a double-acting hand bellows currents of ozone could be
driven over very freely. One of these tubes with hand bellows
attached, which I have had in use for twenty-four years, is before the
meeting, and answers as well as ever. The practical difficulty lies in
the requirement of a battery, a large coil, and a separate bellows as
well as the tube.
My dear and most distinguished friend, the late Professor Polli, of
Milan, tried to overcome the difficulties arising from the use of the
coil by making ozone chemically, namely, by the decomposition of
permanganate of potassa with strong sulphuric acid. He placed the
permanganate in glass vessels, moistened it gradually with the acid,
and then allowed the ozone, which is formed, to diffuse into the air.
In this way he endeavored, as I had done, to purify the air of rooms,
especially those vitiated by the breaths of many people. When he
visited me, not very long before his death, he was enthusiastic as to
the success that must attend the utilization of ozone for
purification, and when I expressed a practical doubt, he rallied me by
saying I must not desert my own child. At the theater La Scala, on the
occasion of an unusually full attendance, Polli collected the
condensible part of the exhaled organic matter, by means of a large
glass bell filled with ice and placed over the circular opening in the
roof, which corresponds with the large central light. The deposit on
this bell was liquid and had a mouldy smell; was for some few days
limpid, but then became very thick and had a nauseous odor. When mixed
with a solution of one part glucose to four parts of water, and kept
at a temperature of from 20° to 24° C., this liquid underwent a slow
fermentation, with the formation, on the superficies, of green must;
during the same period of time, and placed under the same conditions,
a similar glucose solution underwent no change whatever.
By the use of his ozone bottles Polli believed that he had supplied a
means most suitable for directly destroying in the air miasmatic
principles, without otherwise interfering with the respiratory
functions. The ozonized air had neither a powerful nor an offensive
smell, and it might be easily and economically made. The smell of
ozone was scarcely perceptible, and was far less disagreeable than
chlorine, bromine, and iodine, while it was more efficacious than
either of these; if, therefore, its application as a purifier of a
vitiated air succeeded, it would probably supply all the exigences of
defective ventilation in crowded atmospheres. In confined places
vessels might be placed containing mixtures of permanganate of potassa
or soda and acid in proper quantities, and of which the duration of
the action was known; or sulphuric acid could be dropped upon the
permanganate.
This idea of applying ozone was no doubt very ingenious, and in the
bottles before us on the table, which have been prepared in Hastings
by Mr. Rossiter, we see it in operation. The disadvantages of the plan
are that manipulation with strong sulphuric acid is never an agreeable
or safe process, and that the ozone evolved cannot be on a large scale
without considerable trouble.
In 1875 Dr. Lender published a process for the production of ozone. In
this process he used equal parts of manganese, permanganate of potash,
and oxalic acid. When this mixture is placed in contact with water,
ozone is quickly generated. For a room of medium size two spoonfuls of
this powder, placed in a dish and occasionally diluted with water,
would be sufficient. As the ozone is developed, it disinfects the
surrounding air without producing cough.
Lender's process is very useful when ozone is wanted on a limited
scale. We have some of it here prepared by Mr. Rossiter, and it
answers exceedingly well; but it would be impossible to generate
sufficient ozone by this plan for the large application that would be
required should it come into general use. The process deserves to be
remembered, and the physician may find it valuable as a means by which
ozone may be medically applied, to wounds, or by inhalation when there
are foetid exhalations from the mouth or nostrils.
A NEW METHOD.
For the past ten or fifteen years the manufacture of ozone, for the
reasons related above, has remained in abeyance, and it is to a new
mode, which will, I trust, mark another stage of advancement, that I
now wish to direct attention. Some years since, Mr. Wimshurst, a most
able electrician, invented the electrical machine which goes by his
name. The machine, as will be seen from the specimen of it on the
table, looks something like the old electrical machine, but differs in
that there is no friction, and that the plates of glass with their
metal sectors, separated a little distance from each other, revolve,
when the handle of the machine is turned, in opposite directions. The
machine when it is in good working order (and it is very easily kept
in good working order) produces electricity abundantly, and in working
it I observed that ozone was so freely generated, that more than once
the air of my laboratory became charged with ozone to an oppressive
degree. The fact led me to use this machine for the production of
ozone on a large scale, in the following way.
From the terminals of the machine two wires are carried and are
conducted, by their terminals, to an ozone generator formed somewhat
after the manner of Siemens', but with this difference, that the
discharge is made through a series of fine points within the
cylinders. The machine is placed on a table with the ozone generator
at the back of it, and can be so arranged that with the turning of the
handle which works the machine a blast of air is carried through the
generator. Thus by one action electricity is generated, sparks are
discharged in the ozone generator, air is driven through, and ozone is
delivered over freely.
If it be wished to use pure oxygen instead of common air, nothing more
is required than to use compressed oxygen and to allow a gentle
current to pass through the ozone generator in place of air. For this
purpose Brin's compressed oxygen is the purest and best; but for
ordinary service atmospheric air is sufficient.[2]
[Footnote 2: For illustration to-day, Messrs Mayfield, the
electrical engineers of Queen Victoria Street, E. C., have been
good enough to lend me a machine fitted up on the plan named. It
works so effectively that I can make the ozone given off from it
detectable in every part of this large hall.]
The advantages of this apparatus are as follows:
1. With care it is always ready for use, and as no battery is required
nor anything more than the turning of a handle, any person can work
it.
2. It can be readily moved about from one part of a room or ward to
another part.
3. If required for the sick it can be wheeled near the bedside and, by
a tube, the ozone it emits can be brought into action in any way
desired by the physician.
I refer in the above to the minor uses of ozone by this method, but I
should add that it admits of application on a much grander scale. It
would now be quite easy in any public institution to have a room in
which a large compound Wimshurst could be worked with a gas engine,
and from which, with the additional apparatus named, ozone could be
distributed at pleasure into any part of the building. On a still
larger scale ozone could be supplied to towns by this method, as
suggested in Hygeiopolis, the model city.
It will occur, I doubt not, to the learned president of this section,
and to others of our common profession, that care will have to be
taken in the application of ozone that it be used with discretion.
This is true. It has been observed in regard to diseases, that in the
presence of some diseases ozone is absent in the atmosphere, but that
with other diseases ozone is present in abundance. During epidemics of
cholera, ozone is at a minimum. During other epidemics, like
influenza, it has been at a maximum. In our paper Dr. Moffatt and I
classified diseases under both conditions, and the difference must
never be forgotten, since in some diseases we might by the use of
ozone do mischief instead of good. Moreover, as my published
experiments have shown, prolonged inhalation of ozone produces
headache, coryza, soreness of the eyes, soreness of the throat,
general malaise, and all the symptoms of severe influenza cold.
Warm-blooded animals, also, exposed to it in full charge, suffer from
congestion of the lungs, which may prove rapidly fatal. With care,
however, these dangers are easily avoided, the point of practice being
never to charge the air with ozone too abundantly or too long.
A simple test affords good evidence as to presence of ozone. If into
twenty ounces of water there be put one ounce of starch and forty
grains of potassium iodide, and the whole be boiled together, a starch
will be made which can be used as a test for ozone. If ozone be passed
through this starch the potassium is oxidized, and the iodine, set
free, strikes a blue color with the starch. Or bibulous paper can be
dipped in the starch, dried and cut into slips, and these slips being
placed in the air will indicate when ozone is present. In disinfecting
or purifying the air of a room with ozone, there is no occasion to
stop until the test paper, by change of color, shows that the ozone
has done its work of destroying the organic matter which is the cause
of impurity or danger. For my own part, I have never seen the
slightest risk from the use of ozone in an impure air. The difficulty
has always been to obtain sufficient ozone to remove the impurity, and
it is this difficulty which I hope now to have conquered.--_The
Asclepiad._
* * * * *
HEAT IN MAN.
At a recent meeting of the Physiological Society of Berlin, Prof.
Zuntz spoke on heat regulation in man, basing his remarks on
experiments made by Dr. Loewy. The store of heat in the human body at
any one time is very large, equal, in fact, to nearly all the heat
produced by the body during twenty hours, hence the heat given off to
a calorimeter during a given period cannot be taken as a measure of
the heat production. This determination must be based rather upon the
amount of oxygen consumed and of carbonic acid gas given off. The
purpose of the experiments was to ascertain what alteration the
gaseous interchange of the body undergoes by the application of cold,
inasmuch as existing data on this point are largely contradictory.
The observations were made on a number of men whose respiratory gases
were compared, during complete rest, when they were at one time
clothed, at another time naked, at temperatures from 12° to 15° C.,
and in warm and cold baths. Each experiment lasted from half an hour
to an hour, during which period the gases were repeatedly analyzed. As
a result of fifty-five experiments, twenty showed no alteration of
oxygen consumption as the result of cooling, nine gave a lessened
consumption, while the remaining twenty-six showed an increased using
up of oxygen. This diversity of result is explicable on the basis of
observations made by Prof. Zuntz, who was himself experimented upon,
as to his subjective heat sensations during the experiments. He found
that after the first impression due to the application of cold is
overcome, it was quite easy to maintain himself in a perfectly passive
condition; subsequently it required a distinct effort of the will to
refrain from shivering and throwing the muscles into activity, and
finally even this became no longer possible, and involuntary shivering
and muscular contraction supervened, as soon as the body temperature
(_in ano_) had fallen ½° to 1° C. During the first stage of cooling,
Zuntz's oxygen consumption showed a uniform diminution; during the
period also in which shivering was repressed by an effort of the will,
cooling led to no increased consumption of oxygen, but as soon as
shivering became involuntary there was at once an increased using up
of oxygen and excretion of carbonic acid.
This explains the differences in the results of Dr. Loewy's
experiments, and may be taken to show that in man, and presumably in
_large_ animals, heat regulation as directly dependent upon alteration
(fall) in temperature of the surrounding medium does not exist; the
increased heat production is rather the outcome of the movements
resulting from the application of cold to the body. In _small_
animals, on the other hand, there undoubtedly exists a heat regulation
dependent upon an increased activity of chemical changes in the
tissues set up by the application of cold to the surface of the body,
and in this case the thermotaxic centers in the brain most probably
play some part.--Dr. Herter gave an account of experiments made by Dr.
Popoff on the artificial digestion of various and variously cooked
meats. Lean beef and the flesh of eels and flounders were digested in
artificial gastric juice; the amount of raw flesh thus peptonized was
in all cases greater than that of cooked meat similarly treated. The
flesh was shredded and heated by steam to 100° C. The result was the
same for beef as for fish. When compared with each other, beef was, on
the whole, the most digestible, but the amount of fish flesh which was
peptonized was sufficiently great to do away with the evil repute
which fish still has in Germany as a proteid food. Smoked meat
differed in no essential extent from raw meat as regards its
digestibility.
* * * * *
PRESERVATION OF SPIDERS FOR THE CABINET.
For several years past, I have devoted a portion of my leisure time to
the arrangement of the collection of Arachnidæ of the Natural History
Museum of the University of Gand. This collection, which is partially
a result of my own captures, is quite a large one, for a university
museum, since it comprises more than six hundred European and foreign
specimens. Each group of individuals of the small forms and each
individual of the large forms is contained in a bottle of alcohol
closed with a ground glass stopper, and, whenever possible, the
specimens have been spread out and fixed upon strips of glass.
The loss of alcohol through evaporation is almost entirely prevented
by paraffining the stoppers and tying a piece of bladder over them.
Properly labeled, the series has a very satisfactory aspect, and is
easily consulted for study. The reader, however, will readily
understand how much time and patience such work requires, and can
easily imagine how great an amount of space the collection occupies,
it being at least twenty times greater than that that would be taken
up by a collection of an equal number of insects mounted in the
ordinary way on pins and kept in boxes.
These inconveniences led me to endeavor to find out whether there was
not some way of preserving spiders, properly so called, in a dry
state, and without distortion or notable modification of their colors.
Experience long ago taught me that pure and simple desiccation, after
a more or less prolonged immersion in alcohol, gives passable results
only with scorpions, galeodes, phrynes, and mygales, and consequently
with arachnides having thick integuments, while it is entirely
unsuccessful with most of the spiders. The abdomen of these shrivels,
the characteristic colors disappear in great part, and the animals
become unrecognizable.
Something else was therefore necessary, and I thought of carbolated
glycerine. My process, which I have tried only upon the common species
of the country--_Tegenaria domestica_, _Epeira cucurbitina_, _Zilla
inclinata_, etc., having furnished me with preparations that were
generally satisfactory. I think I shall be doing collectors a service
by publishing it in the _Naturaliste_.
The specimens should first be deprived of moisture, that is to say,
they should be allowed to remain eight or ten days in succession in 50
per cent. alcohol and in pure commercial alcohol. Absolute alcohol is
not necessary.
After being taken from the alcohol, and allowed to drain, the
specimens are immersed in a mixture compound of
Pure glycerine 2 volumes,
Pure carbolic acid in crystals 1 volume.
In this they ought to remain at least a week, but there will be no
harm if they are left therein indefinitely, so that the collections of
summer may be mounted during winter evenings.
What follows is a little more delicate, although very easy. After
being removed from the carbolated glycerine, the spiders are placed
upon several folds of white filtering paper, and are changed from time
to time until the greatest part of the liquid has been absorbed. An
insect pin is then passed through the cephalothorax of each individual
and is inserted in the support upon which the final desiccation is to
take place. This support consists of a piece of sheet cork tacked or
glued at the edges to a piece of wood at least one inch in thickness.
Upon the cork are placed four or five folds of filtering paper, so
that the ventral surface of the pinned spider is in contact with this
absorbing surface. For the rest, the legs, palpi, spinnerets, etc.,
are spread out by means of fine pins, precisely as would be done in
the case of coleoptera.
[Illustration: SETTING BOARD FOR SPIDERS.
A. Absorbent papers. B. Sheet cork. C. Wooden support.]
The setting board is put for two or three months in a very dry place
under cover from dust.
The spiders thus treated will scarcely have changed in appearance, the
abdomen of the largest Epeiras will have preserved its form, the hairs
will in nowise have become agglutinated, and a person would never
suspect that glycerine had performed the role.
The forms with a large abdomen require a special precaution; it is
necessary to pass the mounting pin through a piece of thin cardboard
or of gelatine prolonged behind under the abdomen, because the latter
is heavy, and the pedicel that connects it with the cephalothorax
easily breaks.
The specimens are mounted in boxes lined with cork, just as insects
are.
As there is nothing simpler than to have in one's laboratory three
bottles, two of them containing alcohol and the other containing
carbolated glycerine, and as it is easy to make setting boards capable
of holding from twenty to thirty individuals at once, it will be seen
that, with a little practice, the method is scarcely any more
complicated than the one daily employed for coleoptera and orthoptera,
which latter, too, must pass through alcohol, and be pinned, spread
out, and dried. There are but two additional elements, carbolated
glycerine and absorbent paper. I do not estimate the time necessary
for desiccation as being very long, since the zoologist can occupy
himself with other subjects while the specimens are drying. Let us add
that the process renders the preservation indefinite, and that
destructive insects are not to be feared. Some vertebrates, such as
monkeys, that I preserved in the flesh ten years ago, by a nearly
identical method, are still intact.--_F. Plateau, in Le Naturaliste._
* * * * *
DRIED WINE GRAPES.
According to a report of the Committee of the Grape Growers' and Wine
Maker's Association of California, the drying of wine grapes on a
large scale was begun during the vintage season of 1887, in which
season about eight carloads in all were made and sold, the bulk of
which came from the vicinity of Fresno; that year, the committee are
informed, the growers netted about three and a half cents per pound.
During the season of 1888 about 112 carloads were dried, packed, and
sold, netting the growers from two and a half to three and a half
cents per pound, depending on the quality of the fruit. The great bulk
of that year's product has entered into consumption, but there yet
remains unsold to consumers, we are informed, about ten carloads,
which, it is expected, will be sold during the next three months. It
has been observed by those handling this product that the largest
sales of dried wine grapes in 1888 and 1889 took place at those points
to which the first lots were shipped in 1887, which would show that as
the product becomes better known it finds a readier market.
Dried wine grapes are prepared in a similar manner to raisins; that is
they are dried in the sun, but do not require the same care in
handling that are given to raisins. Wooden trays 2 × 3 are sometimes
used, but it is by no means necessary to go to the expense of
procuring trays, as it has been found that a good quality of coarse
brown paper will answer every purpose, and this, with care, may be
made to last two or three seasons. The drying was last season
principally done on the bare ground, but there is much loss by
shelling, as those dried are required to be turned; a pitchfork is
used for that purpose. Brown building paper can be procured of city
paper dealers in large rolls at four and a half cents per pound;
according to the thickness, it will cost from one and three-quarters
to three and a half cents per square yard. A thin, tough, waterproof
paper is also made in rolls at about six cents a square yard. Wine
grapes dry in from ten days to three weeks, according to variety and
weather, and with the exception of Malvoisie, Rose of Peru, and Black
Hamburg, from three and a half to four and a half tons of the green
fruit are required to make one of the dried; these three varieties,
however, being large, meaty, and a firm pulp, do not require more than
from three to three and a half tons of the green fruit to produce one
ton of dried, and are, therefore, the most profitable for drying; they
also command better values in the market. The grapes are sufficiently
dried when, on being rolled between the thumb and finger, no moisture
exudes, and also when the stems are found to be dry and brittle, so
that they can be separated readily from the berries. After the grapes
have reached the proper state of dryness, they are taken in boxes or
sacks to the packing house, where they are stemmed and cleaned, after
which they are packed in white cotton sacks, holding from fifty to
seventy-five pounds each, and when marked are ready for shipment.
The stemming and cleaning of the dried grapes is done by special
machines designed for that purpose, which leaves the fruit in a
bright, clean condition attractive to purchasers. These machines are
at present built only by James Porteous, Fresno, and are operated
either by hand or power. The cost of a stemmer and cleaner complete is
$80, f. o. b. cars at Fresno. Where several producers can do so, it
would be advisable to club together and get the machine in this way.
Much extra expense could be avoided and one set of machinery would
serve several vineyards, possibly an entire district where time was
not a great object; or some one person in a district could purchase an
outfit and do the work by contract, going from place to place. The
capacity of the stemmer and cleaner is from five to eight tons per
day, when the grapes are in proper condition; and the cost or charge
for stemming, cleaning, sacking, and sewing up the sacks is from four
to five dollars per ton when the producer furnishes the sacks. Good
cotton sacks, holding about seventy-five pounds, cost from eight to
ten cents each, including the necessary twine. Last year dried grapes
were generally sold for cash, f. o. b., but it is probable that other
markets could be secured by selling on consignment.
As to the advisability of such a course, each producer must himself be
the judge. It is, however, quite certain that until consumers have an
opportunity to try this product, the sales will necessarily be more or
less limited, unless vigorously pushed by merchants and others
interested in extending the markets for California products in the
Eastern cities not yet tried. The varieties most suitable and
profitable for drying, and especially for consumption in the Eastern
markets, are the Malvoisie, Rose of Peru, Black Hamburg, Mission,
Zinfandel, Charbono, Grenache, and in some localities the Carignan, of
the dark varieties, and the Feher Zagos and Golden Chasselas of the
white grapes; there are many other white grapes that are excellent
when dried, but are too valuable for wine-making purposes, or are too
small or deficient in sugar for use as dried grapes.
The same is true of the dark grapes, some of which ripen so late that
it would be impossible to dry them in the sun, and the use of
artificial heat is, at present prices, too expensive. Therefore, the
varieties mentioned, which generally mature early, are found to be the
most suitable for this purpose. This product is sold by dealers in the
Eastern cities for cooking purposes, and as a substitute for dried
fruits, such as peaches, apples, apricots, etc., in comparison with
which it is usually much cheaper; while for stewing and for puddings
and pies it answers the same purpose. The demand for this product will
probably be gauged by the Eastern fruit crop; that is, the quantity
that can be disposed of will depend upon the quantity of Eastern fruit
in the market, and the prices will be largely dependent upon that of
dried fruit.
* * * * *
WALNUT OIL.
By THOMAS T. P. BRUCE WARREN.
This oil, which I obtained from the fully ripened nut of the _Jugluns
regia_, has so many excellent properties, especially for mixing with
artists' colors for fine art work, that I am surprised at the small
amount of information available on this interesting oil.
Walnut oil is largely used for adulterating olive oil, and to
compensate for its high iodine absorption it is mixed with pure lard
oil olein, which also retards the thickening effect due to oxidation.
The marc left on expression of the oil is said to be largely used in
the manufacture of chocolate. Many people, I am told, prefer walnut
oil to olive oil for cooking purposes.
The value of this oil for out-door work has been given me by a friend
who used it for painting the verandas and jalousies of his house (near
Como, Italy) some twenty years ago, and which have not required
painting since. In this country, at least, walnut oil is beyond the
reach of the general painter, and I do not know that the pure oil is
to be obtained as a commercial article, even on a small scale.
It was in examining the properties of this and other oils, used as
adulterants of olive oil, that I was obliged to prepare them so as to
be sure of getting them in a reliable condition as regards purity. The
walnuts were harvested in the autumn of 1887, and kept in a dry airy
room until the following March. The kernels had shrunk up and
contracted a disagreeable acrid taste, so familiar with old olive oil
in which this has been used as an adulterant. Most oxidized oils,
especially cotton seed oil, reveal a similar acrid taste, but walnut
oil has, in addition, an unmistakable increase in viscosity. The nuts
were opened and the kernels thrown into warm water, so as to loosen
the epidermis; they were then rubbed in a coarse towel, so as to
blanch them. The decorticated nuts were wiped dry and rubbed to a
smooth paste in a marble mortar. The paste was first digested in CS2,
then placed in a percolator and exhausted with the same solvent, which
was evaporated off. The yield of oil was small, but probably, if the
nuts had been left to fully ripen on the trees without knocking them
off, the yield might have been greater. It is by no means improbable
that oxidation may have rendered a portion of the oil insoluble. The
decorticated kernels gave a perfectly sweet, inodorous, and almost
colorless oil, which rapidly thickens to an almost colorless,
transparent, and perfectly elastic skin or film, which does not darken
or crack easily by age. These are properties which, for fine art
painting, might be of great value in preserving the tinctorial purity
and freshness of pigments.
Sulphur chloride gives a perfectly white product with the fresh oil,
but, when oxidized, the product is very dark, almost black. The iodine
absorption of the fresh oil thus obtained is very high, but falls
rapidly by oxidation or blowing. A curious fact has been disclosed
with reference to the oxidation of this and similar oils. If such an
oil be mixed with lard oil, olive oil, or sperm oil, it thickens by
oxidation, but is perfectly soluble. Such a mixture is largely used in
weaving or spinning. Commercial samples of linseed oil, when
cold-drawn, have a much higher iodine absorption, probably due to the
same cause. Oils extracted by CS2 are very much higher than the same
oils, especially if hot-pressed.--_Chem. News._
* * * * *
THE PYRO DEVELOPER WITH METABISULPHITE OF POTASH.
By Dr. J. M. EDER.
Lately I called attention to the metabisulphite of potassium as an
addition to the pyro solution for development, and can give now some
of my experiences with this salt.
The metabisulphite of potassium, which was introduced into the market
by Dr. Schuchardt, and whose correct analysis is not known yet, is a
white crystal, which in a solid condition, as well as in an aqueous
solution, has a strong smell of sulphurous acid. An aqueous 2 per
cent. solution of this salt dissolves pyrogallic acid to a weak
yellowish color, being distinguished from the more light brown
solution of sulphite of soda and pyro. The solution kept very well for
four weeks in half-filled bottles, and showed a better preservation
than the usual solution of pyro and sulphite of soda. More than 2 per
cent. of the metabisulphite of potassium is without any advantage. If
this solution is mixed with soda, a picture will develop rapidly, but
the same will show a strongly yellow coloration in the gelatine film.
Sulphite of soda has to be added to the soda solution to obtain an
agreeable brownish or black tone in the negatives.
If the contents of metabisulphite and pyro-soda developer are
increased, it will act very slowly; larger quantities of the
metabisulphite of potassium, therefore, act like a strong retarder. In
small quantities there is no injurious retarding action, but it will
have the effect that the plates obtain very clear shadows in this
developer, and that the picture appears slower, and will strengthen
more slowly. The strongly retarding action of larger quantities of
metabisulphite might be accounted for in that the bisulphite will
give, with the carbonate of soda, monosulphite and soda bicarbonate,
which latter is not a strong enough alkali to develop the bromide of
silver strongly with pyro. An increase of soda compensates this
retarding action of the metabisulphite of potassium.
Good results were obtained by me with this salt after several tests,
by producing the following solutions:
A.
Pyrogallic acid 4 grammes.
Metabisulphite of potassium 1½ "
Water 100 c. c.
This solution keeps for weeks in corked bottles.
B.
Crystallized soda 10 grammes.
Neutral sulphite of soda 15 "
Water 100 c. c.
Before using mix--
Pyro solution A 20 c. c.
Soda solution B 20 "
Water 20 "
The developer acts about one and a half times slower than the ordinary
pyro soda developer, approaching to the latter pretty nearly, and
gives to the negatives an agreeable color and softness, with clear
shadows. If the negatives are to be thinner, more water, say 30 to 40
c. c., is taken. If denser, then the soda is increased, and the water
in the developer is reduced. An alum bath before fixing is to be
recommended.
An advantage of this development is the great durability of the
pyro-meta sulphite solution. The cost price is about the same as
that of the ordinary pyro developer. At all events, it is worth while
to make further investigation with the metabisulphite of potassium,
the same being also a good preservative for hydroquinone
solutions.--_Photographische Correspondenz; Reported in the Photo.
News._
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