the late Carl ^chorleminer. 193 



are contained in the products of the distillation of coal at 

 low temperatures ; and I would venture the sugjTestion that 

 the so-called paraffins, which are likewise not acted upon by 

 strong acids, may prove to be the higher members of the 

 same series."* 



Schorlemmer next showed, in a communication to this 

 Society, that American petroleum contained the same 

 hydrocarbons which he had isolated from cannel-tar. In 

 1863 he carefully examined the derivatives of heptane from 

 petroleum, and of ethyl-amyl prepared from the iodides of 

 ethyl-amyl. In the following year he proved that equal 

 volumes of chlorine and " methyl " gave, on exposure to 

 light, a volatile liquid boiling at I2°C., which, by analysis and 

 vapour density, he showed to be chloride of ethyl — C2HBCI. 

 He concluded from his experiments that only one series of 

 hydrocarbons existed having the formula C„H2„+2, but the 

 higher members of the series showed slight physical differ- 

 ences according to the mode of their preparation. 



By 1868 the syntheses of various hydrocarbons by 

 Erlenmeyer, Butlerow, Friedel and Ladenburg, and by 

 Schorlemmer himself, led to an important advance. The 

 first three hydrocarbons of the marsh-gas series have no 

 isomers, the higher members may be divided into isomeric 

 groups, according to the mode of combination of the carbon 

 atoms. In the first group the carbon atoms are arranged 

 in a single chain. In the second group one carbon-atom is 

 combined with three others, i.e., the hydrocarbons contain 

 iso-propyl CH3.CH.CH3. The third group contain iso- 

 propyl tzvice ; the fourth group contain a carbon-atom com- 

 bined with four others. The boiling point of members of 

 the first group is higher than that of the corresponding 

 isomers, and a regular difference in boiling point is shown 

 to exist between the several members of the different 



"Jour. Chem. Soc, 1862. Vol. XV., p. 427. 



