HISTORY OF PITGOAl. 17)^ 



exit, always canies some powdered charcoal out of the re- 

 tort. 



> The srasses in this experiment are snch as miight easily be Fvolres car- 

 -> * . X 1 • -J J -1 „bonic' acid and 



toreseen : a mixture or carbonic acid and gaseous oxide ot aaseous oxide, 



carbon, burnini^ with a blue flame, and not detonating. If 



it be yellow, it is owing to the charcoal having retained some 



iiitric acid. This is perceived too by its reddening with oxi- 



gen gas. 



From the great quantity of water formed during this dis- ^uch water 

 tlllation, I was led at first to believe, that the oxigen of the 

 nitric acid, hidrogen, and charcoal, might form together a 

 sort of union comparable to that of a vegetable oxide, which 

 a higher temperature would occasion to be converted into 

 water, carbonic acid, and gaseous ojiide of carbon. Ailni 

 periiaps it is so. Yet the experiment I made immediately 

 witli powder of fir charcoal induced me, to consider the phe- 

 nomena as belonging exclusively to charcoal and oxigen. 



Let nitric acid of 20® or 25° be boiled on calcined char- Wood charcoal 

 coal of fir, elm, or other wood, reduced to powder; the ^^.^^.*^^ ^'^^ 

 pharcoal, after being washed and dried, will commonly have 

 a surcharge of twelve or thirteen per cent. If it be heated 

 with the precautions already given, it will detonate with agi- 

 tationj and afford the two gasses abovementioned, without 

 any mixture of nitrous gas. Other experiments will be seen 

 presently to prove, that this charcoal is in a state of pecu- 

 liar combination, and not contaminated by remains of nitric 

 acid. 



I cannot fix with precision the method of thus oxiding This more va- 

 vegetable charcoal, because I have found it variable. But '^^'^^^^' 

 It is not the same with that of pitcoal, the state of extreme 

 division in which it is when deprived of hidrogen by the acid 

 facilitating that union, so as not to leave us to grope our 

 way. 



Liquid potash, even at a boiling heat, has no action On Oxide of char- 

 pitcoal ; but if heated for a moment, in a very dilute state, coal soluble b/ 

 on its oxide, or that of fir charcoal, a coffee coloured solu- 

 tion holding a considerable quantity is obtained, which is 

 not altered by standing, or by the addition of water. 



Ammonia acts with equal efficacy on them. A hundred and by ammo- 

 grains of oxide of charcoal from Villaneuva coal dissolved "^^* 



in 



