300 Apparatus for Solidifying Carbonic Acid. 
A cast-steel plug with stop-cock precisely similar to the one de- 
scribed, screws into the receiver, as the other does into the gene- 
rator. The tube L screws into the plug which is inserted in the 
receiver, and the other end, turned to a conical point, fits accu- 
rately into a cavity in the plug B, and is held in its place by 
means of the stirrup screw M. Another stirrup screw N, and 
block of wood O, secures the receiver C in its place. 
To use this apparatus the generator and receiver are separated, 
and the plug B being removed, two pounds of bicarbonate of soda, 
made into a paste with the same weight of water, are introduced 
into A, and twenty ounces* of strong sulphuric acid are poured 
into several lead vessels, made by soldering bottoms in pieces of 
lead tube a little shorter than the length internally of the gene- 
rator, and of such a diameter that they will just pass the aperture. 
These being nearly filled with acid are dropped into the genera- 
tor, which, after the plug Bis inserted, is allowed to lie on one 
side for fifteen or twenty minutes, or a less time if it is several 
times rolled over to mix the acid with the soda. The receiver Is 
then attached to it as seen in the figure, by means of the stirrup 
screws M and N; and if kept sufficiently cool by means of ice, 
the liquid carbonic acid formed in A will shortly be distilled ovet 
into C, the passage between them being of course previously 
opened by means of the stop-cocks before described. 
The stop-cocks are now to be closed and the receiver, which 
now contains the liquid carbonic acid, separated from the genera 
tor. A small tin cup is then to be attached to the tube L, pre 
cisely as in Dr. Mitchell’s apparatus,t to receive the jet of acid 
from the receiver. Tt is essential that the liquid acid should escape 
into this cup, which is effected by having a small tube pass from 
the steel plug nearly to the bottom of the receiver, or by inverl- 
ing the receiver before opening the stop-cock. 
The best method of testing the strength of the apparatus, is by 
means of a hydraulic press, but it can be done as effectually by 
permitting it to lie, when charged, exposed to the direct rays © 
the sun, and excluded from currents of air, till the temperature 
Pea hae ea te se eeteall 
- a ne tity of acid required to saturate or neutralize the soda would be @ 
_ than 24 oz., or 22 oz. only if the soda is in crystals, but something less 
Sit ed aiwhre be used. f 
as ee the Franklin Institute, Vol. xx11, p. 289, and Vol. xxxv, P- 346, 0 
