4^GRICULTURAL MUSEUM 9,&T> 



x. modk of ascertaining the quantity oc 

 insoluble finely divided animal and 

 V£:gi;:table IVjatter. 



After the fine matter of the soil has been acted upon by. 

 muriatic acid, the next process is to ascertain the quan- 

 tity of finely divided insoluble animal and vegetable 

 matter that it contains. 



This may be done with sufficient precision, by heating 

 it to stronj^ ignition in a crucible over a common tire 

 till no bla<^kness remains in the ma^s. It should be of. 

 ten stirred with a metallic wire, so as to expose new^ 

 suifaces continually to the air ; the loss of weight that 

 it undergoes dcnirites the q'iantil}^ of the substance that 

 it coiitanis destructible by fire and air. 



It is not possible to asceitain whether this substance 

 is wholly animal or vegetable matter, or a mixtut e of 

 both. When the smell emitted during the incineration 

 is similar to that of burnt feathers, it is a certain indi- 

 cation of some animal mattery and a copious blue flame 

 at the time of ignition, almost always denotes a consi- 

 derable portion of vegetable matter. In cases when 

 the experiment is needed to be very quickiy performed, 

 the destruction of the ilecomposib'e substances may be 

 assisted by the agency of nitrate of ammoniac, which at 

 the time of ignition may be thrown gradually upon 

 the boated mass in the quantity of twenty grains for 

 every hundred of residual soil. It affords the principe 

 necessary to the combustion of the animal and vegeta- 

 ble matter, which it causes to be converted into elas- 

 tic tluids ; and it is itself at the same time decompobe4 

 and lost. 



Xf. Mode of separating aluminous and 



sJLicious xMatter and Oxide of Iron. 



The substances rem lininig after the decomposition of 



the vegetable and animal matter, are generally minute, 



particles of earthy matter, cont;iIning usuaiJy aiumin<y. 



and silex with combined oxide of iron, 



