* 
92 C. M. Warren on the Volatile Hydrocarbons. 
of cannel coal; this substance being so closely analogous to the 
Albert coal (upon the products of which I uid, at that time been 
long engaged) as to induce the belief that, under the same cir- 
cumstances, either would afford the same products. 
I—Own tHe Votatite Hyprocarsoys rrom Coat-rar Napurna, Om 
or Cumin, anp CumInic : 
Part L—Hydrocarbons from Coal-tar Naphtha. 
t 
In presenting the results of a re-examination of a series of sub- 
stances upon which so much labor had already been bestowed, 
and upon the nature and properties of which so little doubt has 
seemed to exist, it may confer an interest on the subject to state 
briefly some of the more important results and conclusions that 
previous investigators have arrived at in the study of these 
substances. 
The discovery by Faraday,’ in 1825, of benzole (“ bicarburet- 
ted hydrogen”) in the oil compressed from oil-gas, rendered it 
highly probable, and indeed led this distinguished philosopher 
to suspect, that this substance might be found in coal-tar naphtha. 
His search for it, however, proved unsuccessful, it having been 
‘first detected by Hofmann in 1845.’ is chemist, however, 
did not attempt to isolate this body, and the bare fact of its pres- 
sence appears to be all that was definitely known of the com 
sition of coal-tar naphtha prior to 1849, in which year Mansfield* 
published his elaborate and valuable research, being the first 
effort at a proximate analysis of this mixture which appears to 
have been attended with any considerable measure of success. 
Although a fatal accident, while engaged in his experiments, 
revented Mansfield from completing the investigation which he 
ad so well begun, yet the work that he had already published: 
in an unfinished state must always be regarded as having con- 
tributed much towards a clear and definite knowledge of the 
nature of the neutral pyrogenous oils contained in. eoal-tar 
out an expenditure of labor, and a degree of patient endurance 
which only those who have experienced the celica tates 
operations can appreciate. 
Mansfield claimed to show that the light coal-tar naphtha is 
eemposed of a mixture of four distinct hydrocarbons, boiling 
* Philosophical Transactions of the Royal Society, 1825 
* Annalen der Chemie und Pharmacie, 1845, Wv.a08: urdtinr 
* Quarterly Journal of the Chemical Society, 1849, i, 244, 
