[148 ] 



and a quarter of which, ten grains of carbonate of 

 lime must be estimated. 



The best method of collecting the carbonic acid, 

 so as to discover its volume, is by a peculiar pneumat- 

 ic, apparatus * in which its bulk may be measured by 

 the quantity of water it dissolves. 



6. After the calcareous parts of the soil has been 

 acted upon by muriatic acid, the next process is to as- 

 certain 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 weight that 

 it undergoes denotes the quantity of the substance 

 that it contains destructible by fire and aif . 



It is not possible, without very refined and diffi- 

 cult experiments, to ascertain whether this substance 



Fig. 15. A, B, C, D, represent the different parts of this apparatus. A. Repre- 

 sents 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 graduated 

 measure. E. The bottle for containing the bladder. When this instrument is used 

 ;* given quantity of soil is introduced 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 disengaged from the soil; for every ounce measure 

 of which two grains of carbonate of lime may be estimated. 



