AND COMPOSITION IN OEOANIC COMPOUNDS. 
267 
difference in composition, this fact arises from the circumstance that the same difference 
in the formulae by no means involves the same difference of boiling-point in all series of 
homologous substances. For the series of the monatomic alcohols with two equivalents 
of oxygen, of the monobasic acids with four equivalents of oxygen, of the ethers to which 
both classes give rise, as well as for a few other series of homologous substances (see 
Table VIII.), the elementary difference x Hg seems to involve a difference of boil- 
ing-point arxl9°; but there are other series of homologous bodies in which the same 
elementary difference is positively attended by another, greater or smaller, difference of 
boiling-point. 
This difference is greater, for example, in the series of hydrocarbons €„ II„_6, in which 
it amounts to about 24°. 
Table XIII. 
Benzol 
Toluol 
Xylol 
Cumol 
Cymol 
V. H, 
Cu H, 
Vs 
VaH, 
^20 ^11 
Kopp, 80°; Mansfield, Church, 81°; Faraday, Mitscherlich, 86°. 
Church, 104°; Deville, 108°; Noad, 110°; Gerhardt, 114°. 
Church, 126 °; Cahours, 129°. 
Abel, Church, 148°; Gerhardt and Cahours, 151°. 
Mansfield, Church, 171° ; Gerhardt and Cahours, 175° ; Kopp, 178°. 
Nearly equally great is the difference in the isolated alcohol radicals CnH^+a. 
Table XIV. 
^13 ^11 • — Propyl, 68° (Williams) ; ethyl-butyl, 62° (Wurtz). 
Hjg : — Methyl-caproyl, 82° (Wurtz); ethyl-amyl, 88° (Wurtz). 
C ,5 Hjg : — Butyl, 106° (Wurtz) ; 108°(Kolbe); 109° (Kopp). 
— Butyl-amyl, 132° (VVurtz). 
Cjo : — Amyl, 155° (Frankland) ; 158° (Wurtz); butyl-caproyl, 155° (Wurtz). 
: — Caproyl (Brazier and Gossleth, Williams), 202°. 
In the acetones and aldehydes C„ Oj, the difference in the boiling-points corre- 
sponding to the elementary difference C 2 H 2 is likewise greater than 19°; the boiling- 
points of several of the terms of these series are, however, but very imperfectly known. 
Those of the acetones seem to have been the more accurately determined. 
Table XV. 
Di£F. 
DifF. 
2C,H, ... 
2C,H, ... 
6C,H, ... 
V Oj ... 
C 10 H 10 O 3 ... 
CuH,0, ... 
^ 26 ^ 29^2 ••• 
Acetone 
Propione 
Butyrone 
CEnanthylone 
Liebig, Dumas, Kopp, 56° 
Limprichl and Uslar, 110 °; Friedel, 111° 
Chancel, about 144°; Friedel, about 145° 
Uslar and Seekamp, 264° 
2 X 22 
2 X 22 
6 x 20 
The boiling-points of the so-called simple and mixed ethers Hn+j ^2 ^Iso differ by 
more than 19° for C 2 H 2 . But in this series also the boiling-points of but few terms 
have been accurately observed. The available data, some of which will claim our atten- 
tion hereafter, are the following : — 
2 N 2 
