Chap. 40.] Lamp Black. *6i 



the procefs is conducted. In general it preserves the 

 form of the vegetable, unlefs that was very fucculent. 

 Pure oils, when decornpofed by heat, afford a coal 

 in very fine particles, called lamp black. 



In whatever manner the volatile matters can be dif- 

 pelled from vegetable or animal fubftances without the 

 admiffion of vital air, which would confume the car- 

 bon, charcoal is produced, which contains no ingre- 

 dient capable of inflammation except carbon, and 

 therefore, with refpect to that procefs, may be confi- 

 dered as carbon itfelf. 



Charcoal, expofed to the greateft heat without the 

 " prelence of vital air, remains unconfumed and un- 

 changed. This fact has been denied by the advocates 

 for the phlogiftic hypothefis, who maintain that the 

 pureft charcoal, treated in this way, affords a'quantity 

 of inflammable gas. It is now, however, I believe, 

 commonly admitted, that if the charcoal is firft accu- 

 rately dried, no inflammable gas is produced, and 

 therefore that which has been obferved by other che- 

 mifts, is to be attributed to the prefence of a fmall 

 quantity of water, which, in a high temperature, is de- 

 compofed by charcoal. Dr. Prieftley has obferved, 

 that charcoal has a ftrong difpofition to attract humi- 

 dity from the atmofphere. He found that charcoal 

 prepared in the evening, and kept till the morning, 

 became fenfibly moid, and unfit for nice experiments. 

 This remarkable attraction for water is, perhaps, to be 

 attributed to the alkaline falts ufually contained in 

 charcoal. 



From the very ftrong attraction which the carbo- 

 naceous principle has for oxygen, there is no fubftance 

 that can be applied to feparate it from that matter. 

 Carbon, on- the contrary, is capable of decompofing 

 all the acids except the boracic, the fluoric, and the 

 S 3 muriatic, 



