﻿594 The late W. Gordon Brown on the 



At the end of the Table are given some results for liquids 

 ordinarily regarded as associated. It will be noticed that in 

 the case of water the value of H + A is approximately zero ; 

 in other words, h + H must be nearly equal but opposite in 

 sign. 



Agreement between the values of \ ex , and \ vap . is not 

 found at temperatures other than the boiling-point. Thus 

 for ether at 0° C, X ex . = $5*5 cals. ; X vap , = 92'5 cals. And 

 from equation (4) it is easy to show that the slope of the 

 \ ex . curve is given by 



1 rfXex. « 2 T 



X ex . dT 1 + dT 



Now at the boiling-point, ocT is approximately * 5 (vide 

 Table above. Hence 



1 d\ 



ex - = --33 a. 



dT 



The average value of — . ,m P " in the neighbourhood 



of the boiling-point is 2a — 3a. 



The Dyson Perrins Laboratory, Oxford. 

 May 12th, 1922. 



LIY . On the Faraday- Tube Theory of Electro- Magnetism. 

 By the late William Gordon Brown*. 



1. riVHE method of describing a field of force by means of 

 A lines or tubes of induction, which originated with 

 Faraday, was given a quantitative form by Sir J. J. Thomson |, 

 and further discussed by N. Campbell in his book ' Modern 

 Electrical Theory/ Since Maxwell himself looked on his 

 work as a mathematical theory of Faraday's lines of force, one 

 is tempted to examine the original physical theory for hints 



* Communicated by Dr. C. G. Knott, F.R.S., General Secretary, R.S.E. 



The young author had just finished his school life at George Watson's 

 College, Edinburgh, when the outbreak of war in 1914 called him to 

 the service of King and Country. He met his death in France on 

 November 13, 1916, at the age of 21. The paper was put in final form 

 about a year earlier when W. G. Brown, after serving in Gallipoli, was 

 in hospital. A short sketch of his life and of his other mathematical 

 notes will be found in the Proceedings of the Roy. Soc. Edin. vol. xlii. 

 1921. 



t ' Recent Researches,' chap. i. ; ' Electricity and Matter,' chap. i. 



