OF ARTS AND SCIENCES. 



61 



ing at 30° and 38°. Since the first two here mentioned, when iso- 

 lated from those of higher boiling-points, are gases at the common 

 temperature, a mixture of these may be more readily obtained in 

 large quantity from a manufactory, by conducting the vapors from 

 the still into a condenser maintained at a low temperature, — be- 

 ing the product introduced by Dr. Henry J. Bigelow for a local 

 anaesthetic under the name of Rhigolene.* The large preponder- 

 ance, in this product, of these most volatile constituents of the 

 petroleum might be inferred from the fact, as stated by him, that 

 when continuously dropped on the bulb of a mercurial thermometer 

 evaporation is so rapid as to cause the mercury to fall to — 7° 

 within 5 to 10 seconds. 



Of the Results of Fractional Condensation. 

 For convenience of reference I will here repeat, with slight mod- 

 ifications, some of the tables from my previous memoir. These 

 exhibit the three homologous series of hydrocarbons that I have 

 separated from the petroleum, together with their boiling-points, 

 the differences of boiling-point corresponding to an elementary 

 difference of -€H 2 , and their formulae, — the data for which are 

 given on the following pages. 



Hydrocarbons from Pennsylvania Petroleum. 

 1. Marsh-gas Series. 



Name of 

 Substance. 



Butyl Hydride 

 Amyl 

 Hexyl " 

 Heptyl " 

 Octyl 

 Nonyl " 



Elementary 

 Difference. 



€H. 2 

 €H 2 

 €H 2 

 €H 2 

 €H- 



Difference of 



Boiling-point 



found. 



30.2 



31.1 



29.1 

 29.1 

 31.3 



Range of Temper- 

 ature within 

 which Substance 

 all distilled. 



1.5 



0.8 

 1.0 

 1.0 

 0.8 



150.8 -^ 5 = 30°.16 

 Average increment of boiling-point for the addition of CH 2 = 30°. 16. 



* Chemical News, 1866, XIII. 244. 



t Ronald's determination. 



