iro 



HISTORY OF PITCOAt. 



Charcoal unites 

 •with oxigcn to 

 form an oxide. 



Coal tieate4 

 ^vith nitric 

 acid, 



gains an in- 

 crease. 



This owing to 

 a real coajbi- 

 jiation. 



Oxide of char- 

 coal, heated, 

 in a retort. 



detonates ob- 

 scurely. 



Oxide of Charcoal. 



Charcoal and oxig-en are susceptible of a kind of union, 

 whicli does not appear to me to have been noticed. It 

 is totally diiierent from carbonic acid, and from gaseous 

 pxide of carbon. These always take place between carbon 

 and oxigen; but the other readily admits chai-coal, whether 

 azotized or not ; such indeed as we burn. The following are 

 the facts. 



A hundred parts of coal of Villanueva,' the coak of which 

 amounts cp Ob, y^e increased by the application of nitric 

 acid at 18° or 20° to 120 or 121 parts. Hence it follows, 

 that, if this acid destroy by ovulation all the principles 

 contained in this bitumen between o;* and 80, it leaves in 

 their place first 32, and next 20, of" sotiie other principle, 

 the nature of which we shall §oon perceive. 



The coal of i3elmez likewise yields 120 or 121 ; that of 

 Langreo the same; and the English, which leaves 64 of coakj 

 proctuces 1 16, which amount to nearly the same. 



That this is not owing to any thing merely imbibed, or to 

 defective washing of the product, is decisively proved by 

 the following experinient. Five drachms of Villanueva coal 

 became 6 by the application of nitric acid. These 6 drachms 

 were thrown into boiling water; but, after they had been 

 collected and dried, they returned precisely to the weight of 

 5 drachms. Such a result clearly shows a surcharge, which, 

 being of 50 Or 52, amounts to half the coal emploj^ed. It is 

 now time to make known its nature. 



Hold in the hand a small retort containing one or two 

 hundred grains of oxided charcoal, its belly being at some 

 distance above a chatingdish, so as to receive a gentle heat, 

 and its beak being kept under water, to give vent to the at- 

 mospheric air, which the aqueous vapour t)egins to expel ; 

 and the instant the powder is agitated by a rapid movement 

 of ebullition, move the beak under an inverted jar tilled with 

 water. This movement, which raises up the charcoal brisk- 

 ly, is a strong' but obscure detonation, which terminates 

 quickly, and without the least danger. At the same time a 

 copious dew is produced, which, by its precipitation at, its 



exit> 



