[ i62 ] 



These coals contain very little afphalt, but chiefly maltha. 



Most coals afford a volatile alkali by diftillation ; this feems 

 to me to be rather a produdl of the operation arifing from the 

 union of hydrogen and mephitic air, and thus the alkaline 

 bafis of the ammoniacs found on volcanos feem to have been 

 formed. Coals alfo afford an acid, commonly the marine, or if 

 pyrituus, alfo the vitriolic, more rarely the fuccinous. 



ArcoRriNG to Mr. Jars, 100 parts of the beft Englifh coal 

 give when chared 63 of coaks*^ but Hielm found the refiduum 



of 



• I Jars, p. 329. 



