A. M., Professor of Natural Science in the Wesleyan University, Mid- 
dietown, Ct.—The remarks I have to make, have reference to the con- 
ditions required in order to obtain the greatest quantity of liquid, and, 
as a matter of course, of solid carbonic acid, from a given mmnliy of 
materials. | 
The different sets of anperaine for solidifying aclatin acid that have 
been made in this country, with one or two exceptions only, it is believed, 
have been constructed in every essential particular, precisely like that 
of Dr. Mitchell,* who enjoys the honor of having been the first in 
America to repeat the beautiful experiment of Thilorier. This appa- 
ratus accomplishes the object perfectly ; but the quantity of solid acid 
obtained from it at a single charge, as it is ordinarily used, is probably 
ably less than the Sage sided: ia eves id 
a little different management. 
- In order to obtain the sitvnice eieailac dt Sha acid, in the liquid 
form, from a given quantity of materials, it seems to be requisite that 
three points be particularly attended to. First, the capacity of the re- 
ceiver should sustain a proper ratio to that of the generator ;+ secondly, es 
the quantity of materials used should be sufficient very nearly to fill the eo 
generator; and thirdly, the difference of temperature between the re- 
ceiver and generator, when the liquid acid is distilled sowie —_ or 
as great as practicable. 
As it regards the first point, without presuming to tae ae on 
the subioth, my experience leads me to think the capacity of the re- 
ceiver should be about one sixth of that of the generator ; certainly it 
should not exceed one fifth. In the apparatus used in this institution,t 
the receiver is but little more than one seventh of the capacity of the 
generator, but at every operation, when the generator is p 
charged, it is completely filled with the liquid acid, and the probability 
is: ‘that 1 more might be obtained if it” was a little larger. If 
were more than just sufficient to contain the acid in the 
liquid Titi that distills over, all the additional space would of course 
be filled with the same acid in the form of gas but exceedingly dense, 
So as to cause = covcninal diminution in the quantity of liquid. Tn x 
Te eee Ce Ne ee 
i ae of the 2 Franklin Siadioeia: Vol, xx, p. 289, and Vol. xxx, p. 346, of this 
Journa 
= ae. Mitchell gave the name, generator, to the vessel into which the bicarb- 
nate of soda, sulphuric acid, &c. for forming the carbonic acid, are east and 
<r d that the ue vr iagoreedt into which the liquid acid is distilled ; and his terms 
t Described in Vol. xxxv “ 1, p. 297, of this Journal. It is there stated that the 
capacity of the receiver is aa ee one pint, but it should have been three gills. 
The mistake was made by attemptin ‘10 ascertain’ its capacity by ex external meas- 
rement 1 leadlidl ine " a 
