ON THE BOILING-POINTS OF PARAFFINS. 115 



XIII. On the Boiling-points of the Normal Paraffins and 

 some of their Derivatives. By Carl Schorlemmer, 

 F.R.S. 



Read February 6th, 1872. 



In several papers published in the years 1842, 1844, 1855, 

 &C.*, Professor H. Kopp showed that there exist certain 

 simple relations between the boiling-points and composi- 

 tion of analogous compounds. According to him, the 

 boiling-points of the members of the homologous series of 

 the alcohols, fatty acids, and their compound ethers are 

 raised 19 for each addition of CH 2 . Afterwards it was 

 stated that in other series this difference is sometimes 

 smaller and sometimes larger, but that it was always the 

 same in the same series. 



In many cases, however, the boiling-points calculated 

 by this rule did not agree at all with those which have 

 been observed. One reason for this discrepancy is that 

 the compounds of which the boiling-points have been 

 compared are not true homologous bodies ; i. e. they have 

 not an analogous constitution, although they differ in 

 their composition by CHj, or a multiple thereof. Thus 

 at that time it was believed that ethyl alcohol, propyl 

 alcohol, and butyl and amyl alcohol from fusel-oil, as 

 well as the so-called capryl alcohol from castor-oil, were 

 true homologues ; but we know now that this is not the 

 case. 



During the last year, however, we have become ac- 

 quainted with a larger number of true homologous bodies, 



* Ann. Chem. Pharm. vol. xli. p, 86, vol. 1. p. 182, vol. xcvi. pp. 2, 330, 

 vol. xcviii. p. 267. 



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