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,
anæmia, 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