Scientific American Supplement No. 819 by Various
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9 [Illustration]
SCIENTIFIC AMERICAN SUPPLEMENT NO. 819
NEW YORK, SEPTEMBER 12, 1891.
Scientific American Supplement. Vol. XXXII, No. 819.
Scientific American established 1845
Scientific American Supplement, $5 a year.
Scientific American and Supplement, $7 a year.
* * * * *
TABLE OF CONTENTS.
I. ASTRONOMY.--The Story of the Universe.--By Dr. WILLIAM
HUGGINS.--A valuable account of modern views of the formation
of the universe, and of modern methods of studying the problem.--1
illustration.
II. ELECTRICITY.--The Production of Hydrogen and Oxygen through
the Electrolysis of Water.--A valuable paper on the electrolysis
of water on a large scale, with apparatus employed therefor.--4
illustrations.
III. MECHANICAL ENGINEERING.--An English Steam Fire Engine.--A
light fire engine built for East Indian service.--1 illustration.
IV. MEDICINE AND HYGIENE.--A Case of Drowning, with Resuscitation.--By
F.A. BURRALL, M.D.--A full account of a remarkable
case of resuscitation from drowning, with full details
of treatment.
V. METALLURGY.--How Gas Cylinders are Made.--The manufacture
of cylinders for highly compressed gases, a comparatively
new and growing industry.--6 illustrations.
Refining Silver Bullion.--The Gutzkow process in refining silver
bullion with sulphuric acid.--1 illustration.
The Treatment of Refractory Ores.--A new process for the extraction
of metal from refractory ore.--1 illustration.
Weldless Steel Chains.--An exhaustive examination of this curious
process, and very full illustrations.--43 illustrations.
VI. METEOROLOGY.--Climatic Changes in the Southern Hemisphere.
--By C.A.M. TABER.--Causes of the climatic changes the
southern hemisphere has undergone.
VII. MILITARY TACTICS.--The System of Military Dove Cotes in
Europe.--Continuation of this paper, treating of the pigeon service
in France, Germany, and Italy.
VIII. NAVAL ENGINEERING.--The Isle of Man Twin Screw
Steamer Tynwald.--A high speed steamer, with a steady sea-going
speed of between 18 and 19 knots.--2 illustrations.
IX. TECHNOLOGY.--Ammonia.--The manufacture of ammoniacal
gas for technical uses.--Full details of its production.
Musical Instruments.--Their construction and capabilities.--By
A.J. HIPKINS.--Second installment of this highly interesting
series of lectures treating of different kinds of instruments.
Note on Refrigerating Apparatus.
Sheet Glass from Molten Metal.--The method of making sheets
of glass from the molten material and manufacture of metal plates
by the same method.
X. VETERINARY SCIENCE.--Historical Development of the
Horseshoe.--By District Veterinarian ZIPPELIUS.--Very curious
investigation of the development of the horseshoe.--22 illustrations.
* * * * *
THE PRODUCTION OF HYDROGEN AND OXYGEN THROUGH THE ELECTROLYSIS OF
WATER.
All attempts to prepare gaseous fluids industrially were premature as
long as there were no means of carrying them under a sufficiently
diminished volume. For a few years past, the trade has been delivering
steel cylinders that permit of storing, without the least danger, a
gas under a pressure of from 120 to 200 atmospheres. The problem of
delivery without pipe laying having been sufficiently solved, that of
the industrial production of gases could be confronted in its turn.
Liquefied sulphurous acid, chloride of methyl, and carbonic acid have
been successively delivered, to commerce. The carbonic acid is now
being used right along in laboratories for the production of an
intense coldness, through its expansion. Oxygen and nitrogen, prepared
by chemical processes, soon followed, and now the industrial
electrolysis of water is about to permit of the delivery, in the same
manner, of very pure oxygen and hydrogen at a price within one's
reach.
Before describing the processes employed in this preparation, we must
answer a question that many of our readers might be led to ask us, and
that is, what can these gases be used for? We shall try to explain. A
prime and important application of pure hydrogen is that of inflating
balloons. Illuminating gas, which is usually employed for want of
something better, is sensibly denser than hydrogen and possesses less
ascensional force, whence the necessity of lightening the balloon or
of increasing its volume. Such inconveniences become serious with
dirigible balloons, whose surface, on the contrary, it is necessary to
diminish as much as possible. When the increasing interest taken in
aerostation at Paris was observed, an assured annual output of some
hundreds of cubic meters of eras for the sole use of balloons was
foreseen, the adoption of pure hydrogen being only a question of the
net cost.
Pure or slightly carbureted hydrogen is capable of being substituted
to advantage for coal gas for heating or lighting. Such an application
is doubtless somewhat premature, but we shall see that it has already
got out of the domain of Utopia. Finally the oxyhydrogen blowpipe,
which is indispensable for the treatment of very refractory metals,
consumes large quantities of hydrogen and oxygen.
For a few years past, oxygen has been employed in therapeutics; it is
found in commerce either in a gaseous state or in solution in water
(in siphons); it notably relieves persons afflicted with asthma or
depression; and the use of it is recommended in the treatment of
albumenuria. Does it cure, or at least does it contribute to cure,
anaemia, that terrible affection of large cities, and the prime source
of so many other troubles? Here the opinions of physicians and
physiologists are divided, and we limit ourselves to a mention of the
question without discussing it.
Only fifteen years ago it would have been folly to desire to obtain
remunerative results through the electrolysis of water. Such research
was subordinated to the industrial production of electric energy.
We shall not endeavor to establish the priority of the experiments and
discoveries. The question was in the air, and was taken up almost
simultaneously by three able experimenters--a Russian physicist, Prof.
Latchinof, of St. Petersburg, Dr. D'Arsonval, the learned professor of
the College of France, and Commandant Renard, director of the military
establishment of aerostation at Chalais. Mr. D'Arsonval collected
oxygen for experiments in physiology, while Commandant Renard
naturally directed his attention to the production of pure hydrogen.
The solutions of the question are, in fact, alike in principle, and
yet they have been developed in a very different manner, and we
believe that Commandant Renard's process is the completest from an
industrial standpoint. We shall give an account of it from a
communication made by this eminent military engineer, some time ago,
to the French Society of Physics.
_Transformations of the Voltameter._--In a laboratory, it is of no
consequence whether a liter of hydrogen costs a centime or a franc. So
long as it is a question of a few liters, one may, at his ease, waste
his energy and employ costly substances.
The internal resistance of a voltameter and the cost of platinum
electrodes of a few grammes should not arrest the physicist in an
experiment; but, in a production on a large scale, it is necessary to
decrease the resistance of the liquid column to as great a degree as
possible--that is to say, to increase its section and diminish its
thickness. The first condition leads to a suppression of the platinum,
and the second necessitates the use of new principles in the
construction of the voltameter. A laboratory voltameter consists
either of a U-shaped tube or of a trough in which the electrodes are
covered by bell glasses (Fig. 1, A and B). In either case, the
electric current must follow a tortuous and narrow path, in order to
pass from one electrode to the other, while, if the electrodes be left
entirely free in the bath, the gases, rising in a spreading form, will
mix at a certain height. It is necessary to separate them by a
partition (Fig. 1, C). If this is isolating and impermeable, there
will be no interest in raising the electrodes sensibly above its lower
edge. Now, the nearer together the electrodes are, the more it is
necessary to lower the partition. The extension of the electrodes and
the bringing of them together is the knotty part of the question. This
will be shown by a very simple calculation.
[Illustration: FIG. 1.--A, B, COMMONEST FORMS OF LABORATORY
VOLTAMETERS. C, DIAGRAM SHOWING ASCENT OF BUBBLES IN A VOLTAMETER.]
The visible electrolysis of water begins at an E.M.F. of about 1.7 V.
Below this there is no disengagement of bubbles. If the E.M.F. be
increased at the terminals of the voltameter, the current (and
consequently the production of gas) will become proportional to the
excess of the value over 1.7 V; but, at the same time, the current
will heat the circuit--that is to say, will produce a superfluous
work, and there will be waste. At 1.7 V the rendering is at its
maximum, but the useful effect is _nil_. In order to make an
advantageous use of the instruments, it is necessary to admit a
certain loss of energy, so much the less, moreover, in proportion as
the voltameters cost less; and as the saving is to be effected in the
current, rather than in the apparatus, we may admit the use of three
volts as a good proportion--that is to say, a loss of about half the
disposable energy. Under such conditions, a voltameter having an
internal resistance of 1 ohm produces 0.65 liter of hydrogen per hour,
while it will disengage 6.500 liters if its resistance be but 0.0001
of an ohm. It is true that, in this case, the current would be in the
neighborhood of 15,000 amperes. Laboratory voltameters frequently have
a resistance of a hundred ohms; it would require a million in
derivation to produce the same effect. The specific resistance of the
solutions that can be employed in the production of gases by
electrolysis is, in round numbers, twenty thousand times greater than
that of mercury. In order to obtain a resistance of 0.0001 of an ohm,
it is necessary to sensibly satisfy the equation
20,000 l/s = 1/10,000
_l_ expressing the thickness of the voltameter expressed in meters,
and _s_ being the section in square millimeters. For example: For l =
1/10, s = 20,000,000, say 20 square meters. It will be seen from this
example what should be the proportions of apparatus designed for a
production on a large scale.
The new principles that permit of the construction of such voltameters
are as follows: (1) the substitution of an alkaline for the acid
solution, thus affording a possibility of employing iron electrodes;
(2) the introduction of a porous partition between the electrodes, for
the purpose of separating the gases.
_Electrolytic Liquid._--Commandant Renard's experiments were made with
15 per cent, solution of caustic soda and water containing 27 per
cent. of acid. These are the proportions that give the maximum of
conductivity. Experiments made with a voltameter having platinum
electrodes separated by an interval of 3 or 4 centimeters showed that
for a determinate E.M.F. the alkaline solution allows of the passage
of a slighter intenser current than the acidulated water, that is to
say, it is less resistant and more advantageous from the standpoint of
the consumption of energy.
_Porous Partition._--Let us suppose that the two parts of the trough
are separated by a partition containing small channels at right angles
with its direction. It is these channels alone that must conduct the
electricity. Their conductivity (inverse of resistance) is
proportional to their total section, and inversely proportional to
their common length, whatever be their individual section. It is,
therefore, advantageous to employ partitions that contain as many
openings as possible.
The separating effect of these partitions for the gas is wholly due to
capillary phenomena. We know, in fact, that water tends to expel gas
from a narrow tube with a pressure inversely proportional to the
tube's radius. In order to traverse the tube, the gaseous mass will
have to exert a counter-pressure greater than this capillary pressure.
As long as the pressure of one part and another of the wet wall
differs to a degree less than the capillary pressure of the largest
channel, the gases disengaged in the two parts of the trough will
remain entirely separate. In order that the mixing may not take place
through the partition above the level of the liquid (dry partition),
the latter will have to be impenetrable in every part that emerges.
The study of the partitions should be directed to their separating
effect on the gases, and to their electric resistance. In order to
study the first of these properties, the porous partition, fixed by a
hermetical joint to a glass tube, is immersed in the water (Fig. 2).
An increasing pressure is exerted from the interior until the passage
of bubbles is observed. The pressure read at this moment on the
manometer indicates (transformed above the electrolytic solution) the
changes of level that the bath may undergo. The different porcelains
and earths behave, from this point of view, in a very unequal manner.
For example, an earthen vessel from the Pillivayt establishment
supports some decimeters of water, while the porcelain of Boulanger,
at Choisy-le-Roi, allows of the passage of the gas only at pressures
greater than one atmosphere, which is much more than is necessary.
Wire gauze, canvas, and asbestos cloth resist a few centimeters of
water. It might be feared, however, that the gases, violently
projected against these partitions, would not pass, owing to the
velocity acquired. Upon this point experiment is very reassuring.
After filling with water a canvas bag fixed to the extremity of a
rubber tube, it is possible to produce in the interior a tumultuous
disengagement of gas without any bubbles passing through.
[Illustration: FIG. 2.--ARRANGEMENT FOR THE STUDY OF CAPILLARY
REACTION IN POROUS VESSELS.]
From an electrical point of view, partitions are of very unequal
quality. Various partitions having been placed between electrodes
spaced three centimeters apart, currents were obtained which indicated
that, with the best of porcelains, the rendering of the apparatus is
diminished by one-half. Asbestos cloth introduces but an insignificant
resistance.
To this inconvenience of porous vessels is added their fragility,
their high price, and the impossibility of obtaining them of the
dimensions that large apparatus would call for. The selection of
asbestos cloth is therefore clearly indicated; but, as it does not
entirely separate the gases, except at a pressure that does not exceed
a few centimeters of water, it was always necessary to bring back the
variation of the level to these narrow limits by a special
arrangement. We cannot, in fact, expect that the entire piping shall
be always in such conditions that no difference in pressure can occur.
The levels are brought back to equality within the effective limits by
interposing between the voltameter and the piping an apparatus called
a compensator, which consists of two vessels that communicate in the
interior part through a large tube. The gases enter each vessel
through a pipe that debouches beneath the level of the water. If a
momentary stoppage occurs in one of the conduits, the water changes
level in the compensator, but the pressure remains constant at the
orifice of the tubes. The compensator is, as may be seen, nothing more
than a double Mariotte flask. When it is desired to obtain pure gases,
there is introduced into the compensator a solution of tartaric acid,
which retains the traces of alkalies carried along by the current of
gas. The alkaline solution, moreover, destroys the ozone at the moment
of its formation.
It will be seen that laboratory studies have furnished all the
elements of a problem which is now capable of entering the domain of
practice. The cheapness of the raw materials permits of constructing
apparatus whose dimensions will no longer be limited except by reasons
of another nature. The electrodes may be placed in proximity at will,
owing to the use of the porous partition. It may be seen, then, that
the apparatus will have a considerable useful effect without its being
necessary to waste the electric energy beyond measure.
_Industrial Apparatus._--We have shown how the very concise researches
of Commandant Renard have fixed the best conditions for the
construction of an industrial voltameter. It remains for us to
describe this voltameter itself, and to show the rendering of it.
[Illustration: FIG. 3.--PLANT FOR THE INDUSTRIAL ELECTROLYSIS OF
WATER.]
The industrial voltameter consists of a large iron cylinder. A battery
of such voltameters is shown to the left of Fig. 3, and one of the
apparatus, isolated, is represented in Fig. 4. The interior electrode
is placed in an asbestos cloth bag, which is closed below and tied at
its upper part. It is provided with apertures which permit of the
ascent of the gases in the interior of the cylinder. The apparatus is
hermetically sealed at the top, the two electrodes being naturally
insulated with rubber. Above the level of the liquid the interior
electrode is continuous and forms a channel for the gas. The hydrogen
and oxygen, escaping through the upper orifices, flow to the
compensator. The apparatus is provided with an emptying cock or a cock
for filling with distilled water, coming from a reservoir situated
above the apparatus.
[Illustration: FIG. 4.--DETAILS OF AN INDUSTRIAL VOLTAMETER.]
The constants of the voltameter established by Commandant Renard are
as follows:
Height of external electrode 3.405 m.
" internal " 3.290 "
Diameter of external " 0.300 "
" internal " 0.174 "
The iron plate employed is 2 millimeters in thickness. The electric
resistance is about 0.0075 ohm. The apparatus gives 365 amperes under
2.7 volts, and consequently nearly 1 kilowatt. Its production in
hydrogen is 158 liters per hour.
It is clear that, in an industrial exploitation, a dynamo working
under 3 volts is never employed. In order to properly utilize the
power of the dynamo, several voltameters will be put in series--a
dozen, for example, if the generating machine is in proximity to the
apparatus, or a larger number if the voltameters are actuated by a
dynamo situated at a distance, say in the vicinity of a waterfall.
Fig. 3 will give an idea of a plant for the electrolysis of water.
It remains for us to say a few words as to the net cost of the
hydrogen and oxygen gases produced by the process that we have just
described. We may estimate the value of a voltameter at a hundred
francs. If the apparatus operates without appreciable wear, the
amortizement should be calculated at a very low figure, say 10 per
cent., which is large. In continuous operation it would produce more
than 1,500 cubic meters of gas a year, say a little less than one
centime per cubic meter. The caustic soda is constantly recuperated
and is never destroyed. The sole product that disappears is the
distilled water. Now one cubic meter of water produces more than 2,000
cubic meters of gas. The expense in water, then, does not amount to a
centime per cubic meter. The great factor of the expense resides in
the electric energy. The cost of surveillance will be minimum and the
general expenses _ad libitum_.
Let us take the case in which the energy has to be borrowed from a
steam engine. Supposing very small losses in the dynamo and piping, we
may count upon a production of one cubic meter of hydrogen and 500
cubic decimeters of oxygen for 10 horse-power taken upon the main
shaft, say an expenditure of 10 kilogrammes of coal or of about 25
centimes--a little more in Paris, and less in coal districts. If,
consequently, we fix the price of the cubic meter of gas at 50
centimes, we shall preserve a sufficient margin. In localities where a
natural motive power is at our disposal, this estimate will have to be
greatly reduced. We may, therefore, expect to see hydrogen and oxygen
take an important place in ordinary usages. From the standpoint alone
of preservation of fuel, that is to say, of potential energy upon the
earth, this new conquest of electricity is very pleasing. Waterfalls
furnish utilizable energy in every locality, and, in the future, will
perhaps console our great-grandchildren for the unsparing waste that
we are making of coal.--_La Nature._
* * * * *
[Continued from SUPPLEMENT, No. 818, page 13066.]
MUSICAL INSTRUMENTS: THEIR CONSTRUCTION AND CAPABILITIES.
By A.J. HIPKINS, F.S.A.
LECTURE II.
I will now invite your attention to the wind instruments, which, in
Handel's time, were chiefly used to double in unison the parts of
stringed instruments. Their modern independent use dates from Haydn;
it was extended and perfected by Mozart, Beethoven, and Weber; and the
extraordinary changes and improvements which have been effected during
the present century have given wind instruments an importance that is
hardly exceeded by that of the stringed, in the formation of the
modern orchestra. The military band, as it now exists, is a creation
of the present century.
The so-called wood wind instruments are the flute, oboe, bassoon, and
clarinet. It is as well to say at once that their particular qualities
of tone do not absolutely depend upon the materials of which they are
made. The form is the most important factor in determining the
distinction of tone quality, so long as the sides of the tube are
equally elastic, as has been submitted to proof by instruments made of
various materials, including paper. I consider this has been
sufficiently demonstrated by the independent experiments of Mr.
Blaikley, of London, and Mr. Victor Mahillon, of Brussels. But we must
still allow Mr. Richard Shepherd Rockstro's plea, clearly set forth in
a recently published treatise on the flute, that the nature and the
substance of the tube, by reciprocity of vibration, exercise some
influence, although not so great as might have been expected, on the
quality of the tone. But I consider this influence is already
acknowledged in my reference to equality of elasticity in the sides of
the tube.
The flute is an instrument of _embouchure_--that is to say, one in
which a stream of air is driven from the player's lips against an edge
of the blow hole to produce the sound. The oboe and bassoon have
double reeds, and the clarinet a single reed, made of a species of
cane, as intermediate agents of sound production. There are other
flutes than that of _embouchure_--those with flageolet or whistle
heads, which, having become obsolete, shall be reserved for later
notice. There are no real tenor or bass flutes now, those in use being
restricted to the upper part of the scale. The present flute dates
from 1832, when Theobald Boehm, a Bavarian flute player, produced the
instrument which is known by his name. He entirely remodeled the
flute, being impelled to do so by suggestions from the performance of
the English flautist, Charles Nicholson, who had increased the
diameter of the lateral holes, and by some improvements that had been
attempted in the flute by a Captain Gordon, of Charles the Tenth's
Swiss Guard. Boehm has been sufficiently vindicated from having
unfairly appropriated Gordon's ideas. The Boehm flute, since 1846, is
a cylindrical tube for about three-fourths of its length from the
lower end, after which it is continued in a curved conical
prolongation to the cork stopper. The finger holes are disposed in a
geometrical division, and the mechanism and position of the keys are
entirely different from what had been before. The full compass of the
Boehm flute is chromatic, from middle C to C, two octaves above the
treble clef C, a range of three octaves, which is common to all
concert flutes, and is not peculiar to the Boehm model. Of course this
compass is partly produced by altering the pressure of blowing.
Columns of air inclosed in pipes vibrate like strings in sections,
but, unlike strings, the vibrations progress in the direction of
length, not across the direction of length. In the flute, all notes
below D, in the treble clef, are produced by the normal pressure of
wind; by an increasing pressure of overblowing the harmonics, D in the
treble clef, and A and B above it, are successively attained. The
fingerholes and keys, by shortening the tube, fill up the required
intervals of the scale. There are higher harmonics still, but
flautists generally prefer to do without them when they can get the
note required by a lower harmonic. In Boehm's flute, his ingenious
mechanism allows the production of the eleven chromatic semitones
intermediate between the fundamental note of the flute and its first
harmonic, by holes so disposed that, in opening them successively,
they shorten the column of air in exact proportion. It is, therefore,
ideally, an equal temperament instrument and not a D major one, as the
conical flute was considered to be. Perhaps the most important thing
Boehm did for the flute was to enunciate the principle that, to insure
purity of tone and correct intonation, the holes must be put in their
correct theoretical positions; and at least the hole below the one
giving he sound must be open, to insure perfect venting. Boehm's
flute, however, has not remained as he left it. Improvements, applied
by Clinton, Pratten, and Carte, have introduced certain modifications
in the fingering, while retaining the best features of Boehm's system.
But it seems to me that the reedy quality obtained from the adoption
of the cylindrical bore which now prevails does away with the sweet
and characteristic tone quality of the old conical German flute, and
gives us in its place one that is not sufficiently distinct from that
of the clarinet.
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