VII. 



Researches on the Volatile Hydrocarbons. 



By C. M. WARREN. 



Communicated October Wth, 1864. 



Introductory Remarks. — While engaged, a few years since, in attempting to Kparate 

 some of the constituents of coal-tar naphtha by the common process of fractional 

 distillation, I was forced to the conviction that that process could not be safely relied 

 upon for anything like a complete and accurate analysis of such a complex mixture of 

 liquids ; and that, at best, the products thus obtained could not be regarded as any- 

 thing better than remote approximations to pure substances ; leaving reason to fear 

 that there might still be other bodies present, in lesser quantities perhaps, which had 

 escaped detection. 



An examination of the results of previous researches on tars, petroleums, etc., served 

 in general to confirm the impressions induced by my own less extended experiments ; 

 and to increase, rather than lessen, the doubts already existing in my mind as to the 

 trustworthiness of the results which had hitherto been published concerning the 

 neutral constituents of such mixtures. Influenced by these considerations, and by the 

 belief that, if I could succeed in finding a process capable of effecting a more com- 



paration of the constituents of 



ight probably lead to th 



discovery of new bodies, lying between those which had already been described, — I 

 was led to undertake the researches, the results of which I am about to record. 

 Even if this chief purpose should fail, I was convinced that the expenditure of labor 

 in isolating those bodies in a state of greater purity, would be amply compensated by 

 the much needed confirmation, or perhaps correction, of the results previously pub- 

 Hshed, in addition to the valuable incidental evidence of the absence of other bodies 

 which would thus be furnished. The results which I have obtain. 1 in the pursuit 

 of this object are abundantly sufficient to show that I did not undervalue the work of 

 my predecessors, nor over-estimate the importance of the work before me. 



The success which attended my efforts in search of a better process of separation 



