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° 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
G¹, 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 ½ 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_.
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