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the ad of detonnation nitre is always totally or partially decom- 

 pofed ; and fince where carbonaceous compounds are employed this 

 decompofition arifes folely from the mere carbonaceous part, and 

 every thing elfe being equal, is proportioned to the quantity of 

 mere carbon they contain ; and fince moft fpecies of coals are 

 compounds of mere carbon and bitumen, as appears by the pro- 

 duds of their diftillation, it fhould follow, that by the decom- 

 pofition of nitre the quantity of mere carbon in a given quantity 

 of every fpecies of coal may be difcovered, and this being known, 

 that of bitumen may be inferred, and the other unefTential ingre- 

 dients being deteded by incineration, the whole contents of coaly 

 fubftances might be afcertained. 



The compofition of bitumens alfo, as far as relates to their 

 proportion of carbon and oil, may be evidenced in the fame man- 

 ner : And here it is to be obferved that the bitumens I here con- 

 fider are thofe that are found in a dry or folid ftate, and that 

 thefe contain a larger proportion of carbon than the liquid bitu- 

 mens ; for though thefe laft alfo contain carbon, it being an elTcn- 

 tial component part of all oils, yet this portion does not extricate 

 or educe any air from nitre, nor confequently contribute to its 

 decompofition, as the fubfcquent experiments fufficiently evince, 

 but is confumed partly by the pure air fpontaneoufly emitted by 

 nitre during its ignition, and partly by the ambient atmofphaeric 

 air. Nay, when mineral coal is employed in the decompofition 

 of nitre, the fiiare which the mere carbonaceous part of the bitu- 

 men contained in it contributes to the decompofition will be found 

 fo fmall that it merits no confideration in the general account. 



The 



