﻿The Boiling-Points of Homologous Compounds. 599 

 Applebey and Chapman obtain (p. 737) tbe value of -j- 



by applying the law of rectilinear diameters, and the 

 relation 



8p\ _ 2R 

 v. 



\8t\ 



where the suffix c denotes that the measurement is made at 

 the critical point. 



Mills, on the other hand, uses the law of rectilinear 

 diameters to obtain the critical constants, chooses the con- 

 stants of Biotas formula to fit the values so found, and then 

 shows that the result 



\OtJc V c 



is true — a process equivalent mathematically to that used by 

 Applebey and Chapman. 



LX. The Boiling-Points and Critical Temperatures of Homo- 

 logous Compounds, By Allan Ferguson, JD.Sc. (Lond.), 

 Assistant Lecturer in Physics in the University College of 

 North Wales , Bangor* . 



^ITEE present communication explains a new empirical 

 X formula which appears to represent the relation between 

 the boiling-points and molecular weights of the normal 

 paraffins with considerable accuracy over a wide range, and 

 also establishes, for the same series, empirical formulae 

 showing the relation between critical temperature and 

 chemical constitution — a relation which does not, hitherto, 

 appear to have attracted very much notice. 



It would serve no useful end to disturb the dust which 

 has collected over formulae more than a generation old : in 

 discussing previous results it will be sufficient for our pur- 

 poses to consider the boiling-point equations proposed by 

 Walker |, by Eamage J, and by Young § . 



Walker's formula is of the type 



. 0=oM», (i.) 



where Sis the absolute boiling-point, M the molecular weight, 



* Communicated by Prof. E. Taylor Jones, D.Sc. 

 + Trans. Cliem. Soc. lxv. pp. 193, 725 (1894). (For earlier references 

 see this paper.) 



% Camb. Phil. Soc. Proc. xii. p. 445 (1904). 

 § Phil. Mag. Jan. 1905, p. 1. 



