I JO Proportions of Charcoal in Wood and Pit- Coal. 



of pit-coals, T have reafon to believe that they contain .1 

 fmall portion of fnccinic acid. The collected products from 

 30 lb. of pit-coal afforded me about one dram of a particular 

 fait, which, by its fmell, indicated the prefence of that 

 acid. 



But what more particularly arretted my attention in the 

 analyfes of pit-coal was a very peculiar combination of fome 

 of 'the carbonaceous matter with .a portion of fulphur, and 

 where pyrites was not prefent. A coal in the vicinity of 

 Almaden, in Eftremaclura, which contains no pyrites, yields 

 very white allies, and from which no fnlphur can be ob- 

 tained by dillillation, exhibits, however, as it paffes from 

 ineandefcence to incineration, proofs of containing fulphur, 

 which, becoming o.xydated along with the coal, makes it 

 fcnfible to the fmell. A peculiar carburet of fulphur there- 

 fore exifls in this coal ; but combuftion is necefl'ary to its 

 decompofition. Expofed to the greateft heat, this coal neither 

 difcolours (ilver, nor affects iron in the forge. 



This Angular phenomenon, happily perhaps for the 

 arts, is one of the caufes which fo beneficially retard or pro- 

 Jong the combuuion of pit-coal. Phofphorus combined 

 with charcoal is much le-fs combuftible than when alone : 

 neither the contact of atmofpheric air, nor even the com- 

 bined action of alkalis and water, is fufficient to fepa- 

 rate phofphorus from its combination with carbon. From 

 the difficulty with which the carbonaceous portion of ani- 

 mal fubftances is burnt, the lame inference may be drawn 

 fefpe&ing fulphur'; for fulphur is known to ex i ft in a con- 

 fidcrabie proportion in animal fubftances. Wool, unquef- 

 tionably, contains much fulphur, but none paffes over when 

 that matter is diftilled. Where then can it remain, if not in 

 union with the carbonaceous refiduum ? That refiduum 

 mould be examined with a view to this point. One thing is 

 certain, that foap of wool, prepared in a filver veffel, deeply 

 fulphurates its interior fu;Aice. 



XV. Lei- 



