cL i News,
February 28, 1879.
Ea ——— re
spheres and temperature of 62° should become reduced to Between these two motive cylinders is a heavy fily-wheel
—103° F. on being discharged, putting aside deductions of about 7 tons weight, It became very evident in the
for friction, &c. This illustrates the limitless production carly stages of construction that some kind of automatic
of cold by such a process; for let the initial pressure be regulator would be required, so that the speed of the
higher, say zo or 30 atmospheres, and the cooling effe® machine should ne such as to exercise no undue suction
will correspondingly be produced. Indeed, itseemstome upon the shale retorts, otherwise atmospheric air might
that if Messrs. Pictet and Cailletet had in their experi- have been taken into the machine in admixture with the
ments made the compressed oxygen or hydrogen do more hydrocarbon gases. This was accomplished by putting a
work in expanding than the mere displacement of the small gasometer governor between the two motive cylinatmosphere,
 then they would have been liquefied at much ders just described, and adjusted so delicately that a varialower
 pressures. M. Pictet employed no less than gooo Ibs. tion of pressure equivalent to 0°25 would, by a system of
pressure per square inch in his experiments. But it can [evers, attuate a throttle-valve and open or close the
be shown that a compression of only one-tenth of this, admission of steam to the cylinder, and thus regulate the
or goo lbs. per square inch, raises a gas to 1200° F.; and speed of the engine. These levers, when once adjusted,
that if gas so compressed be brought down to 60° and cause the engine to run at full speed of 80 revolutions
then expanded in the a of doing work, it must neces: when the pressure in the retorts rose to 0'75 (or $) inch, and
sarily be cooled down to a lower degree than any yet ex- to run at half speed when the pressure sank to o'25 inch,
perimentally shown, and which would probably be We will now trace the progress of the hydrocarbon gases,
sufficient to effe@ the liquefaction of any gas we are They are sucked into two pumps worked by the motive
acquainted with. * cylinders A and Ar, the piston rods of which extend to the
Again, in their experiments there must have been a pro- two pumps, and are therein compressed to about 8 atmodu@ion
 of heat militating against the liquefaction from spheres absolute, or alittle more than 100lbs. per square inch
the fri®ion of the gases in escaping into the atmosphere above the ordinary atmosphere. Under these circumstances
through a minute orifice. some hundreds of degrees of heat are generated which
This is the theoretical aspect of the case, but in praftice require to be removed : this is accomplished in great part
several considerations arise. by injecting about 8 cubic inches of water into each pump
It is very difficult constru@ing the necessary appa. cvery stroke of the engine. This water is forced into the
ratus strong enough without having such a mass of gas-pump by small inje@ion-pumps. The compressed
metals as to communicate heat rapidly to its contents; zas is now conveyed by the pipes with injected water to
and, further, the friction of the piston rings and the rubbing :he top of a surface condenser, and passes downwards
surfaces of the valves, piston-rods, &c., is difficult to through 200 iron tubes of about 1 inch diameter and 4 feet
neutralise, lubrication at excessively low temperatures 6 inches long, these tubes being surrounded with cold
being troublesome. water. The mixture of compressed gas, liquefied hydro-How
 far these difficulties may be overcome on original carbons, and injected water arrives at length at about
research remains to be proved ; but they have been dealt 70° F. in reservoir at bottom of the surface condenser.
with to some extent in machinery constructed under my The water and liquefied hydrocarbons are allowed to
direction for technical purposes, and it may be observec =scape by an automatic regulated cock, and the comthat
 this machinery differs essentially from apparatus pre- pressed air is carried to the top of a second surface conviously
 used, inasmuch as its construction admits of the denser, precisely similar in construction and with precisely
liquefied gases being produced in a continuous stream, similar outlets at the bottom reservoirs. Itis then carried
whereas in all former experiments with the liquefaction of (orward to the top of the third surface condenser, where it
gases, a small volume has been first confined and lique: rst passes downwards through a chamber packed with
fied, the experiment then coming to an abrupt end. salt, so as to convert any suspended mixture into brine,
In a paper read to the Chemical Society of London and afterwards further downwards through 200 more
(Sept., 1875) I described the effe® of pressure and cold t-inch iron pipes in the case not surrounded with water.
upon the gaseous products of the distillation of carbona. I'he compressed gas-still of about 8 atmospheres pressure
ceous shales, which remain permanent after all the con: is finally used for working the motive cylinder, which does
densable vapours within are removed in the usual way by not differ in constru@ion fiom a steam cylinder, from which
cooling to atmospheric temperature. These gases, whilst it is discharged after doing work considerably below zero
being permanent at 50° yield under the influence of a Fahr. This constant stream of ejected and cold gas is
pressure of about Io atmospheres and a cold of 200° large made to circulate around the condensing pipes of the
quantities of volatile liquid hydrocarbons, consisting third surface condenser, and is finally carried away to be
chiefly of butylen, amylen, hydride of amyl, and hexylen. burnt as fuel under the boiler, being chiefly a residue of
The machine which is the subje@ of this paper wat marsh-gas and hydrogen.
designed to deal with 300,000 cubic feet per day of this The cycle is thus complete, and it only becomes neceswaste
 gas, by subjecting it to the cold and pressure just sary to indicate all the cylinders and note the volumes and
mentioned, and has now been working three years, ‘emperatures of the incoming wtaer and gas and their final
having liquefied, in round numbers, about a quarter of a temperatures to have most interesting proof of some of
million gallons of these liquid hydrocarbons. It involves— he Moth important fundamental laws of thermo-dynamics.
. } g he machine was driven by steam of 50 Ibs. initial pres-{r.)
 TE eer owas inte 2 sure, and when it became desirable to indicate the cylincooled,
 and from which condensed liquids can be ders the working pressure was kept as nearly as possible
’ too lbs. to the square inch, and the piston speed moderate,
drawn off by ball-cocks. viz., 144 feet per minute (48 Tui Under th
Employing the compressed gas after being deprived I a BS was f ol 1] oh utions). Under these
of its liquid for working a second engine coupled | ” . o . BE tigre
with and parallel to the first, thus receiving a por- ~~ Motive cylinder A indicated .. .. .. .. 33h.p.
tion of the force originally employed in the com. a nw Ar, er ee ee ee 7 gy
pression. . —_—
(3.) Employing the expanded gas after having had its Total driving power. . Se se ee as 40
temperature reduced in the a& of doing the work ~~ The gas-pumps offered a resistance of.. .. 32 ,,
of pumping for supplying the necessary cold for . —_—
cooling a portion of the condenser pipes to zero. Difference .. +. +0 +o wo we. 8
The machinery is kept in motion by the piston’s cylin. The indicator cards show that the volume of
ders, A and A 1, the pistons of which are conne@ed with compressed gas introduced into cylinder A 1 became rea
 common crank shaft, both being of 30-inch stroke. duced to atmospheric pressure by the end of the stroke.

38

The Liquefaction of Gases.