the Distillation of Coal Tar 289 



It dissolves in acetic acid, and is not much mote soluble in 

 tUe hot, than in the coW acid. 



Muriatic acid scarcely dissolves it. 



In sulphuric acid, when aided by heat, it dissolves in consi- 

 derable abundance, forming a deep violet-coloured solution, 

 .which bears diluting with water wilhout decomposition. The 

 alcalies produce in this solution a white flaky precipitate, and 

 if diluted, the mixture becomes curiously opalescent, in conse- 

 quence of the separation of numerous small flakes. 



By long-continued boiling with sulphuric acid, a portion of 

 «arbon is deposited ; but the greater part of the substance 

 volatilizes unaltered. 



Repeatedly distilled with nitric acid, this substance appears 

 to suffer scarcely any change ; a portion is retained in solution, 

 by the ^icid, which is precipitated by dilution, and another 

 portion passes over unaltered. 



In the caustic and carbonated alkalis, it is scarcely soluble. 

 This substance appears to suffer no change whatever by je- 

 j)eated subhmations, at temperatures above that of boiling water; 

 .and what is more curious, is, that its vapour may be passed 

 through a red hot tube without decomposition ; if received into 

 a cool glass globe, it crystallizes in white plates as before. 



Fused with potassium, it scarcely acts upon that metal ; 

 and as the mixture cools, it oozes from it in brilliant o-Iobules. 



Such are the few experiments whidi I have hitherto been 

 able to. make upon this peculiar product. It bears in appearance 

 so strong a resemblance to the fatty matter of biliary calculi, 

 that I was once induced to consider it nearly of the same nature ; 

 but, as Dr. Wollaston remarked to me, it is not only much les* 

 fusible, but considerably less volatile, than that compound, and 

 perhaps approaches, in most respects, nearer to the properties of 

 camphor, than of any other known body ; though, as the above 

 cxj^rimcnts tend to shew, it exhibits several peculiarities. 



Its remarkable indestructibility by heat ; the circumstance of 

 its neither affording water nor carbonic acid, when heated in 

 close vessels, and its very trifling action upon potassium, are 

 circumstances which induce me to believe that it contains no 



