Scientific American Supplement, No. 358, November 11, 1882

V >> Various >> Scientific American Supplement, No. 358, November 11, 1882

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VINCENT'S CHLORIDE OF METHYL ICE MACHINE.

Chloride of methyl was discovered in 1840 by Messrs. Dumas and Peligot,
who obtained it by treating methylic alcohol with a mixture of sea salt
and sulphuric acid. It is a gaseous product at ordinary temperature, but
when compressed and cooled, easily liquefies and produces a colorless,
neutral liquid which enters into ebullition at 237.7 deg. above zero and
under a pressure of 0.76 m.

[Illustration: VINCENTS ICE MACHINE. FIG. 1.--THE FREEZER (Longitudinal
Section).]

Up to recent times, chloride of methyl in a free state had received
scarcely any industrial application, by reason of the difficulty of
preparing it in a state of purity at a low price. Mr. C. Vincent,
however, has made known a process which permits of this product being
obtained abundantly and cheaply. It consists in submitting to the action
of heat the hydrochlorate of trimethylamine, which is obtained as a
by-product in the manufacture of potash of beets. The hydrochlorate
is thus decomposed into free trimethylamine, ammonia, and chloride
of methyl. A washing with hydrochloric acid takes away all traces of
alkali, and the gas, which is gathered under a receiver full of water,
may afterward be dried by means of sulphuric acid, and be liquefied by
pressure.

[Illustration: VINCENTS ICE MACHINE. FIG. 2.--THE FREEZER (Transverse
Section).]

Pure liquid chloride of methyl is now an abundant product. There are two
uses to which it is applied: first, for producing cold, and second, for
manufacturing coal tar colors.

[Illustration: VINCENTS ICE MACHINE. FIG. 3.--HALF PLAN OF FREEZER]

At present we shall occupy ourselves with the first of such
applications--the production of cold.

The apparatus serving for the production of cold by this material are
three in number: (1) the _freezer_ (Figs. 1, 2, and 3), in which is
produced the lowering of temperature that converts into ice the water
placed in carafes or any other receptacles; (2) the _pump_ (Figs. 4, 5,
and 6), which sucks the chloride of methyl in a gaseous state up into
the freezer and forces it into the liquefier; and (3) the _liquefier_,
which is nothing else than a spiral condenser in which the chloride of
methyl condenses, and from thence returns to the freezer to serve anew
for the production of cold.

[Illustration: VINCENTS ICE MACHINE. FIG. 4.--THE PUMP (Longitudinal
Section).]

_The Freezer_.--This consists of a rectangular iron tank, 1 meter x 1
meter x 1.5 meters, containing a galvanized plate iron cylinder, A, kept
in place by iron supports. This cylinder contains 24 horizontal tubes,
which are open at the ends and riveted to vertical plates like those of
tubular steam boilers. The tank is filled with a mixture of water and
chloride of calcium, forming, as well known, an incongealable liquid.
Into this liquid are plunged the receptacles containing the water to be
converted into ice. The chloride of methyl is introduced through the
cock, B, into the body of the cylinder, A, and surrounds and cools the
tubes, as well as the incongealable liquid uninterruptedly circulating
in the latter, by means of a helix, C, set in motion by a belt from the
shop. This liquid is thus greatly lowered in temperature and freezes the
water in the receptacles.

[Illustration: VINCENTS ICE MACHINE. FIG. 5.--VERTICAL SECTION OF THE
PUMP.]

_The Pump_.--The pump in the larger apparatus has two chambers of
unequal diameter, that is to say, it operates after the manner of
compound engines.

The machine under consideration, being one that produces a moderate
quantity of ice, has but a single chamber, as shown in Figs 4, 5, and 6.
It is a suction and force pump, whose piston, E, is solid and formed of
two parts, which are set into each other, and the flanges of which hold
a series of bronze segments.

[Illustration: VINCENTS ICE MACHINE. FIG. 6.--PLAN OF THE PUMP.]

The chamber, properly so-called, is of iron, cast in one piece, and is
surmounted with a rectangular tank, F, in which constantly circulates
the cold water designed for cooling the sides of the cylinder; these
latter always tending to become heated through the compression of the
methyl chloride.

The cylinder heads are hollowed out in the middle, and carry the seats
of the suction valves. Each of the latter communicates with a chamber, G
G, in which debouches the pipe, H, communicating with the cylinder, A,
of the freezer (Figs. 1, 2, and 3).

[Illustration: VINCENTS ICE MACHINE. FIG. 7.--THE LIQUEFIER.]

Above the cylinder there are two delivery valves which give access to
the chamber, D, communicating with the worm of the liquefier (Fig. 7)
through the pipe, J.

The piston of the pump is set in motion by a pulley, K, and a cranked
shaft actuated by a belt from the shafting. The piston head is guided by
a slide keyed to the frame.

[Illustration: VINCENTS ICE MACHINE. FIG. 8.--SECTION OF FLANGE OF THE
WORM.]

_The Liquefier_.--This apparatus consists of a cylindrical tank, L, of
3 mm. thick boiler plate, mounted vertically on a masonry base and
designed to be constantly fed with cool water. It contains a second
cylindrical tank, M, of 6 mm. thick galvanized iron. This latter tank is
provided with a cast-iron cover, on which are mounted the worm, N, and a
pipe, O, connected with the tube of the pressure gauge. To the base of
the tank, M, there is affixed, on a cast iron thimble, a cock, P, for
setting up a communication between the tank and the pipe, R, which
returns to the freezer through the cock, B (Fig. 1).

[Illustration: VINCENTS ICE MACHINE. FIG. 9.--VIEW OF THE UNDERSIDE OF
THE SAME.]

The cold water requisite for condensation enters the tank, L, through
a pipe terminating in a pump or a reservoir. The waste water flows off
through the tubulure, Q. The tank is emptied, when necessary, through
the blow-off cock, S.

[Illustration: VINCENTS ICE MACHINE. FIG. 10.--PLAN OF THE WORM.]

_Operation of the Apparatus_.--As has been remarked above, the cylinder,
A, is filled with chloride of methyl. The pump, through suction,
produces in this cylinder a depression from which there results the
evaporation of a portion of the chloride of methyl, and consequently
a depression of temperature which is transmitted to the incongealable
liquid circulating in the tubes, and to the receptacles (carafes or
otherwise) containing the water to be converted into ice.

The pump sucks in the vapor of mythyl chloride through the pipe, H, and
through its suction valves, and forces it into the chamber, D, through
its delivery valves, and from thence into the worm, N, through the pipe,
J. Under the influence of compression and of the water contained in the
tank, L, the methyl chloride liquefies and falls into the receptacle, M,
from whence it returns to the freezer through the pipe, R.

Two pressure-gauges, one of them fixed on the freezer and the other on
the liquefier, permit of regulating the running of the machine. The
vacuum in the freezer is 0 to 1/2 atmosphere, and the pressure in the
liquefier is 3 to 4 atmospheres. These apparatus make opaque ice, but
will likewise produce transparent, if a pump for injecting air is
adjoined. This, however, doubles the time that it takes to effect the
freezing, and carries with it the necessity of doubling the number of
moulds to have the same quantity of ice.

The cost price of ice made by this system depends evidently on the price
of coal in each country, on the perfection of the boiler and motor, as
well as on the power of the freezing machine. Putting the coal at 20
francs per ton, and the consumption at 2 kilogrammes per horse and
per hour, ice may be obtained at a cost of about half a centime per
kilogramme. The apparatus shown in the accompanying figures have been
constructed according to the following data:

Production of ice per hour............ 25 kilogrammes.
Production of heat units per hour..... 2.5 grammes.
Quantity of ice produced per
kilogramme of coal burned........... 5 kilogrammes.
Water of condensation per hour........ 0.75 cubic meter.

These machines are employed not only for the manufacture of ice, but
also in breweries for cooling the air of the cellars and fermenting
rooms, or that of the vats themselves; in manufactories of chemical
products; in distilleries; in manufactories of aerated waters, etc.

They may also be used in the carrying of meats and other food products
across the ocean, and, in a word, in all industries in which it is
necessary to obtain artificial cold.

The power necessary to operate apparatus that produce 25 kilogrammes per
hour is about that of 3 horses.--_Annales Industrielles_.

* * * * *

CARBONIC ACID IN THE AIR.

[Footnote: An address before the Paris Academy.]

By M. DUMAS.

Of all the gases that the atmosphere contains, there is one which offers
a special interest, as well on account of the part ascribed to it in
the mutual interchange going on between the two organic kingdoms, as
on account of the relation that it has been observed to occupy between
earth, air, and water; this gas is carbonic acid.

Ever since the fact has been established that animals consume oxygen
and give out carbonic acid as the product of respiration, while plants
consume carbonic acid and give out oxygen, the question has often been
asked whether the quantity of carbonic acid contained in the air did not
represent a sort of sustaining reservoir which was being continually
drawn on by the plants and resupplied by animals, so that it has
doubtless remained unchanged owing to this double action.

On the other hand, Boussingault has long since shown that volcanic
regions give out through crevices and fumaroles enormous quantities of
carbonic acid. The deposition of carbonate of lime that is continually
taking place on the sea-bottom is, on the other hand, fixing carbonic
acid in quantities which we may accurately estimate from the strata of
limestone seen on the surface of the earth. We might imagine, that in
comparison with the huge volumes of carbonic acid sent forth in volcanic
districts, even in the oldest one, and the mass of carbonate of lime
deposited on the sea bottom, the results attributed to the life of
plants and animals would be of no consequence either for increasing or
diminishing the physiological carbonic acid in the air comparable with
those which are accomplished by the purely geological exchange.

Schloesing has recently succeeded, by a happy application of the
principle of dissociation, in showing that the amount of carbonic acid
in the air bears a direct relation to the quantity of bicarbonate
of lime dissolved in sea water. If the quantity of carbonic acid
diminishes, the bicarbonate of the water is decomposed, half of its
carbonic acid escapes into the atmosphere, and the neutral carbonate of
lime is precipitated. The aqueous vapor condensed from the air dissolves
part of the carbonic acid contained therein, and carries it along, when
it falls as rain upon the earth, and takes up there enough lime to form
the bicarbonate, which is thus carried back to the sea.

The physiological role of carbonic acid, its geognostic influence, and
its relations to most ordinary meteorological phenomena on the earth's
surface--all these contribute to give special weight to studies
concerned in the estimation of the normal quantity of carbonic acid in
the air.

Nevertheless, this estimation is attended with great difficulty. Not
everyone is able to take up such questions, and not all processes are
adapted to it. The first thought which would naturally arise would be to
inclose a known volume of air in a given vessel, and then determine its
carbonic acid by measuring or weighing it. In this way we should obtain
the exact relation between a volume of air and the volume of carbonic
acid in it, for any given moment, and in any given place. If, however,
this be done with a ten-liter flask, for example, it would only hold
3 c.c. of carbonic acid, weighing 6 milligrammes; and, whether it is
weighed or measured, the error may easily equal 10 per cent. of the real
value, hence no deductions could be drawn from the observed facts.

For this reason larger volumes of air were taken, and a current of air,
whose volume could be accurately measured by known methods, was passed
through condensers capable of retaining the carbonic acid. But in this
case the air must pass very slowly through it, so that the process may
last several hours; and since the air is continually in motion, owing to
vertical and horizontal currents, the experiment may be begun with the
air of one place, and concluded with air from a far distant spot. For
example, if an experiment lasting twenty-four hours was made in Paris
when the air moved but four meters per second (nine or ten miles per
hour), it might be begun with air from the Department of the Seine, and
end with air from the Department of the Rhone, or the Belgian frontier,
according to the direction of the wind.

So long as we had no analytical methods of sufficient delicacy to
estimate with certainty the hundredth, or at least the tenth of a
milligramme of carbonic acid, it was very difficult to determine the
quantity in the air at a given time and place. It is frequently possible
to analyze upon the plain air that has descended from the heights
above, and to examine by bright daylight the effect of night upon the
atmosphere.

Still other difficulties show themselves in such investigations. It
seems very easy to collect carbonic acid in potash tubes, and to
determine its amount from the increase in weight of the tubes; but,
alas! to how many sources of error is this method exposed. If the potash
has been in contact with any organic substance, it will absorb oxygen.
If the pumice that takes the place of the potash contains protoxide of
iron, it will also absorb oxygen. In both cases the oxygen increases the
weight of the carbonic acid.

Every experimenter who has been compelled to repeat the weighing of a
somewhat complicate piece of apparatus, with an interval of several
hours between, knows how many inaccuracies he is exposed to if he is
compelled to take into calculation the changes of temperature and
pressure, and the moisture on the surface of the apparatus. After
fighting all these difficulties, and frequently in vain, the
experimenter begins to mistrust every result that depends only on
difference in weight, and to prefer those methods whereby the substance
to be estimated can be isolated, so that it can be seen and handled,
weighed or measured, in a free state, and in its own natural condition.

The classical experiments of Thenard, of Th. de Saussure, of Messrs.
Boussingault, on the quantity of carbonic acid in the air, are well
known to every one: they need only to be organized, repeated, and
multiplied.

J. Reiset, who has conducted a long and tedious series of experiments on
this subject, has adopted a process that seems to offer every guarantee
of accuracy. The air that furnishes the carbonic acid is aspirated
through the absorption apparatus by two aspirators of 600 liters
capacity. The temperature and pressure of the air are carefully
measured. The carbonic acid is absorbed by baryta water in three bulb
apparatus. The last bulb, which serves as a check to control the
operation, remains clear, and proves that no binoxide of barium
is formed. The baryta water used is titrated before and after the
operation, and from the difference is calculated the quantity of
carbonate formed, and hence of the carbonic acid.

These tedious experiments, which varied in duration from 6 to 25 hours,
require at least two days of continuous labor. They were repeated
193 times by Reiset in 1872, 1873, and 1879. They were made in still
weather, and in violent winds and storms. The air was taken at the
sea-shore, in the middle of the fields, on the level earth, during
harvests, in the forests, and in Paris. Under such varied conditions,
the quantity of carbonic acid varied but little; the numbers obtained
were between 2.94 and 3.1, which may be taken as a general average of
the carbonic acid in the air.

The quantity of carbonic acid in the free atmosphere is tolerably
constant, which must necessarily be the case according to Schloesing's
proposed relation between the bi-carbonate of lime in the sea and the
carbonic acid in the air. The only cause that seems at all competent to
change the geological quantity of carbonic acid in the atmosphere is
the formation of fog. As the aqueous vapors condense, they collect the
carbonic acid; and the foggy air, as a rule, is more heavily laden with
this gas than ordinary air.

It is not surprising that there is less carbonic acid in the air
collected on clear summer days, in the midst of clover, etc., that is in
an active reducing furnace; if anything is surprising, it is that the
quantity of carbonic acid does not sink below 2.8.

It is also a matter for surprise that in Paris, among so many sources of
carbonic acid, the furnace fires, the respiration of men and animals,
and the spontaneous decomposition and decay of organic substances, the
quantity of carbonic acid does not exceed 3.5.

If, then, the great general mean of normal atmospheric carbonic acid
deviates but little from 2.9 or 3.0, it is not doubtful that under local
conditions, in closed places, and under exceptional meteorological
conditions, considerable variations may occur in these proportions. But
these variations do not affect the general laws of the composition of
the atmosphere.

There are two entirely distinct points from which the measurement of the
atmospheric carbonic acid may be contemplated.

The first consists in considering it as a geological element which
belongs to the gaseous envelope of the earth in general, and it leads us
to express the general relation of carbonic acid to the quantity of air,
as about three volumes in 10,000.

The second, which relates to accidental and local phenomena, to the
activity of man and beast, to the effect of fires and of decomposing
organic matter, to volcanic emanations, and finally to the action of
clouds and rain, permits us to recognize the changes which can occur
in air exposed to the influences mentioned, and to a certain extent
confined. Without denying that it is of interest from a meteorological
and hygienic standpoint, it does not take the same rank as first.

J. Reiset's experiments, by their number, accuracy, the large volumes
employed, and the interval of years that separate them, have definitely
established two facts on which the earth's history must depend: the
first is, that the percentage of carbonic acid in the air scarcely
changes; the second, that it differs but little from three
ten-thousandths by volume.

These results are fully confirmed by the results which were obtained by
Franz Schulze, in Rostock, in 1868, 1869, 1870, and 1871. The averages
which he got, with very small variation, were 2.8668 for 1869, 2.9052
for 1870, and 3.0126 for 1871.

More recently Muentz and Aubin have analyzed air collected on the plains
near Paris, on the Pic du Midi, and on the top of Puy-de-Dome. Their
results agree with those published by Reiset and Schulze.

The grand average of carbonic oxide in the air seems to be tolerably
fixed, but after this starting-point is established it remains to study
the variations that it is capable of, not from local causes, which are
of little importance, but from general causes connected with large
movements of the air. Upon this study, which demands the co-operation of
a definite number of observers stationed at different and distant
points of the earth, the experiments being made simultaneously and by
comparable methods.

M. Dumas called the attention of the Academy to this point, in
connection with its mission of selecting suitable stations for observing
the transit of Venus. The process and apparatus of Muentz and Aubin
offer the means adapted for making these experiments, and seem
sufficient to solve the problem which science proposes, of determining
the present quantity of carbonic acid in the air.

If these experiments yield satisfactory results, as we have good reasons
to believe they will, it is to be hoped that annual observations will be
made in properly-chosen places, so as to determine the variations which
may possibly take place in the relative quantity of atmospheric carbonic
acid during the coming century.--_Compt. Rend_., p. 589.

[Although this proposition was made by a Frenchman to his fellow
scientists, would it not be well for some American to accept the
challenge, and bring it before the coming meeting of the American
Association for the Advancement of Science, in the hope that we,
too, may contribute our mite of effort in the same direction?--_Ed.
Knowledge_.]

* * * * *

THE INFLUENCE OF AQUEOUS VAPOR ON THE EXPLOSION OF CARBONIC OXIDE AND
OXYGEN.

[Footnote: Read before the British Association, Southampton Meeting,
Section B, 1882.]

By HAROLD B. DIXON, M.A., Millard Lecturer in Chemistry, Balliol and
Trinity Colleges, Oxford.

Two years ago I had the honor of showing before the Chemical Section of
the British Association some experiments, in which a well-dried mixture
of carbonic oxide and oxygen was submitted to electric sparks without
exploding.[1] It was further shown that the introduction of a very
minute quantity of aqueous vapor into the non-explosive mixture was
sufficient to cause explosive combination between the gases when the
spark was passed. The hypothesis advanced to account for the observed
facts was that carbonic oxide does not unite directly with oxygen at
a high temperature, but only indirectly through the intervention of
water-vapor present, a molecule of water being decomposed by one of
carbonic oxide to form a molecule of carbonic acid and one of free
hydrogen, and the latter uniting with the oxygen to re-form a molecule
of water, which again undergoes the same cycle of changes, till all the
oxygen is transferred to the carbonic oxide:

H_{2}O + CO = H_{2} + CO_{2}

H_{2} + O = H_{2}O

[Footnote 1: "Report of British Association," 1880, p. 503.]

For such a series of reactions a _comparatively_ few molecules of water
would suffice, and the change produced by their alternate reduction and
oxidation would come under the old term of "catalytic action," inasmuch
as the few water molecules present at the beginning are found in the
same state at the completion of the reaction.

The truth of this hypothesis has since been confirmed by experiments I
have made on the incomplete combustion of mixtures of carbonic oxide and
hydrogen; and on the velocity of explosion of carbonic oxide and oxygen
with varying proportions of aqueous vapor. I therefore thought a
description of the more convenient methods lately devised as lecture
experiments for showing the influence of water on the combustion of
carbonic oxide would not be uninteresting to the Section.

A glass tube from 18 inches to 2 feet long, closed at one end, and
provided with platinum wires, is bent near its open end so that the
shorter arm makes an angle of about 60 deg. with the longer arm. The tube,
held by a clamp, is heated in a Bunsen flame, and is then filled with
mercury heated to about 130 deg. C. The mixture of gases is then made to
displace a portion of the mercury by forcing it through a fine tube,
which is connected by a steel cap to the eudiometer of McLeod's gas
apparatus, and passes down through the mercury in the shorter arm of the
experimental tube. When a sufficient quantity of the gaseous mixture
has been collected in the longer arm, some dry phosphoric oxide is
introduced in the following way: A small glass tube is heated, packed
with the dry powder, and pushed down into the shorter arm of the
experimental tube. With a hot glass rod the phosphoric oxide is pushed
out at the bottom of the small tube, and passes up into the gaseous
mixture in the longer arm. After standing for a few hours in contact
with the phosphoric oxide, the gases may be submitted to strong sparks
from a Leyden jar without igniting. Care must be taken that none of the
oxide comes in contact with the platinum wires, for if any sticks to
the wires it becomes heated by the passage of the sparks, and gives off
enough water to determine the explosion. In this way I have prepared
several specimens of a non-explosive mixture of carbonic oxide and
oxygen in the proper proportions to form carbonic acid. Some of these
tubes have been submitted without explosion to sparks from a large
Leyden jar, to a continuous succession of sparks from a Holtz machine,
and to the discharge of a Ruhmkorff's coil, that heated the platinum
wires between which it passed to bright redness. Other tubes which
withstood the passage of the sparks from a Leyden jar, when submitted
to the discharge of the coil, exploded after a few seconds when the
platinum wires became red-hot. This I think may probably be attributed
to hydrogen, occluded by the platinum, being given off on heating, and
forming steam with the oxygen present.

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