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the quantity of carbonic acid lost ; for every four 
grains and a quarter of which, ten grains of car- 
bonate of lime must be estimated. 
The best method of collecting the carbonic acid, 
so as to discover its volume, is by a peculiar pneu- 
matic apparatus # , in which its bulk may be mea- 
sured by the quantity of water it displaces. 
6. After the calcareous parts of the soil have been 
acted upon by muriatic acid, the next process is 
to ascertain the quantity of finely-divided insoluble 
animal and vegetable matter that it contains. 
This may be done with sufficient precision, by 
strongly igniting it in a crucible over a common 
fire till no blackness remains in the mass. It should 
be often stirred with a metallic rod, so as to expose 
new surfaces continually to the air : the loss of 
* Fig. 15. A, B, C, D, represent the different parts of this 
apparatus. A represents the bottle for receiving the soil. 
B the bottle containing the acid, furnished with a stop-cock. 
C the tube connected with a flaccid bladder. D the gra- 
duated measure. E the bottle for containing the bladder. 
When this instrument is used, a given quantity of soil is intro- 
duced into A. B is filled with muriatic acid diluted with an 
equal quantity of water ; and the stop-cock being closed, is 
connected with the upper orifice of A, which is ground to receive 
it. The tube D is introduced into the lower orifice of A, and 
the bladder connected with it placed in its flaccid state into E, 
which is filled with water. The graduated measure is placed 
under the tube of E. When the stop-cock of B is turned, the 
acid flows into A, and acts upon the soil ; the elastic fluid 
generated passes through C into the bladder, and displaces a 
quantity of water in E equal to it in bulk, and this water flows 
through the tube into the graduated measure ; and gives by its 
volume the indication of the proportion of carbonic acid disen- 
gaged from the soil; for every ounce measure of which two 
grains of carbonate of lime may be estimated. 
