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is wholly animal or vegetable matter, or a mixture of 

 both. When the smell emitted during the incinera- 

 tion is similar to that of burnt feathers, it is a certain 

 indication of some substance either animal or analo- 

 gous to animal matter ; and a copious blue flame at 

 the time of ignition, almost always denotes a consi- 

 derable proportion of vegetable matter. In cases 

 when it is necessary that the experiment should be 

 very quickly performed, the destruction of the decom- 

 posable substances may be assisted by the agency of 

 nitrate of ammoniac, which at the time of ignition may 

 be thrown gradually upon the heated mass in the 

 quantity of twenty grains for every hundred of residual 

 soil. It accelerates the dissipation of the animal and 

 vegetable matter, which it causes to be converted into 

 elastic fluids ; and it is itself at the same time decom- 

 posed and lost. 



7- The substances remaining after the destruc- 

 tion of the vegetable and animal matter, are generally 

 minute particles of earthy matter, containing usually 

 alumina and silica, with combined oxide of iron or 

 of manganesum. 



To separate these from each other, the solid mat- 

 ter should be boiled for two or three hours with sul- 

 phuric acid, diluted with four times its weight of wa- 

 ter ; the quantity of the acid should be regulated by 

 the quantity of solid residuum to be acted on, allow- 

 ing for every hundred grains, two drachms or one 

 hundred and twenty grains of acid. 



The substance remaining after the action of the 

 acid, may be considered as siliceous j and it must be 



