TAKNING MATTER, &:C. 23 



ble substances, there cannot be any doubt, that vegetable Experiments 

 bodies when roasted, yield solutions by digestion in &c.onthearti- 

 water, which essentially consist of carbon approaching ficial substance 

 , « ,,, , Ti^i i.j having thecha- 



to the state, of coal, although not absolutely converted ^^Lcter of tan- 



intoit, for if so, all solubility in water would cease. ning matter. 



But coal is apparently nothing more than carbon oxi- 

 dized to a certain degree, and may be formed by the hu- 

 mid as well as by the dry way. 



Examples have been already stated respecting opera- 

 tions in which sulphuric acid has produced this effect, 

 but the same likewise appears to be produced with some 

 modifications, whenever vegetable matter undergoes the 

 putrefactive process; for when this takes place, as in 

 dunghills, &c. a large proportion of the carbon of the ori- 

 ginal vegetable substances appears to be Combined with 

 oxygen sufficient to communicate to it many of the pro- 

 perties of coal, whilst the compound nevertheless is capa- t 

 ble of being dissolved by water with the most perfect 

 facility. 



It must not however be understood that by this process ' 

 all the other elementary principles are separated, so that 

 only the carbon remains combined with oxygen, but 

 merely, that the other principles are so far diminished, 

 that these, namely, carbon and oxygen, predominate in a 

 state approaching to coal, although soluble in water. 



Such solutions, I have every reason to believe, are 

 nearly similar to those afforded by vegetable substances 

 which have been previously roasted, and although I have 

 examined but a few of them, yet I shall relate some expe- 

 riments which I have lately made on the pdels of walnuts. 



It is well known that when these are kept in small 

 heaps for a short time, they become soft, and break down 

 into a black mass, which affords a brownish-black liquor. 

 On these I therefore made the following experiments ; 



1. 



About one ounce of walnut peels, which were become 

 soft and black, was digested in water. 



A dark brown liquor was thus formed, and being fil- 

 trated, was examined by a solution of isinglass, but not 

 any apparent effect was produced. 

 2. 



On an ec^ual quantity of walnut peels, in the satne soft 



black 



