160 
POPULAR SCIENCE REVIEW. 
Fig. 4. 
M. Eaoul Pictet was described, and its advantages mentioned. It 
will be remembered that intense cold is produced in this machine 
by the evaporation in vacuo of sul- 
phurous acid liquefied by pressure. 
In continuation, as it were, of this 
subject comes the following de- 
scription of the most perfect and 
elaborate refrigerating apparatus, 
capable of withstanding enormous 
pressures, which has hitherto been 
constructed. It is the invention of 
M. Pictet, and is a further develop- 
ment of his ice-machine. 
The accompanying drawings (figs. 
3 and 4), show the general arrange- 
ment of its parts, while some idea 
of its very considerable dimensions 
may be gained from the fact that 
the manometer near the letter (n)is 
raised from the ground about the 
height of a man, while the room is 
capable of holding more than thirty 
persons. 
A howitzer shell (b), containing 
7 00 grammes (a pound and a half ) 
of chlorate of potash, mixed with 
chloride of potassium to moderate 
its decomposition. It is heated 
with gas. 
(aa', fig. 4.) A tube, over 16 feet 
in length, \ inch external diameter, 
and £ inch internal diameter, in 
which the oxygen condenses. It is 
furnished with a screw-tap at a', 
from which the liquefied gas streams 
forth. A pressure-gauge measures 
the pressure up to 800 atmo- 
spheres. 
(c) A tube, 13 feet in length, 
in which is solid carbonic acid. 
The stock of carbonic acid is con- 
tained in a gasholder (g), 220 gal- 
lons in capacity. A three-way tap 
places it, when desired, in connec- 
tion with the apparatus. 
(f) A non-conducting covering, with a wooden casing. 
(d) A tube of 2J inches diameter, and 3 feet 7 inches long, 
