C. M. Warren on the Volatile Hydrocarbons. 89 
Art. XII.—Researches on the Volatile Hydrocarbons; by C. M. 
WARREN.’ 
Introductory Remarks.—While engaged, a few years since, in 
attempting to separate some of the constituents of coal-tar naph- 
tha 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 re ty of such 
a complex mixture of liquids; and that, at best, the products 
thus obtained could not be regarded as anything better than re- 
mote approximations to pure substances ; leaving reason to fear 
that there might still be other bodies present, in less quantities 
perhaps, which had escaped detection. 
An examination of the results of previous researches on tars, 
petroleums, ete., served in general to confirm the impressions 
induced by my own less extended experiments; and to increase, 
? From the Memoirs of the American Academy, (N. 8.) ix, 135. 
Am, Jour. Scl.—Szconp Series, Vou. XL, No. 118,—Juty, 1865. 
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