igos] Mills — Molecular Attraction. 91 



Propyl alcohol. A = antilog (2.8340346 + .001641423/) 



+ antilog- (.03135244 - .00342975/), 

 | t = t° C - 20. 



The constants for ethyl formate and methyl acetate were 

 I kindly sent me by Dr. Young- (work yet unpublished) and the 

 I constants for methyl formate I have calculated and will pub- 

 lish later. 



The values of the -«7Fr a t the critical temperature as obtained 

 o 1 



; i from these Biot equations are shown in Table 1. 



Of the twenty substances compared in Table 1 it will be 



8 P 

 seen that the -r=- from equation 4 has a higher value than the 

 61 



8 P 



»7p calculated from Biot's formula in all cases except di-iso- 



butyl, normal octane, and ethyl alcohol. The difference is 

 usually very marked. 

 In work done upon an equation of the form, P = bT — a, 



8P 

 ^Ramsay and Young 1 made a study of the -^Tp of ether at con- 

 stant volume, Young- 2 , later, a similar study for isopentane, 

 and Rose-Innes and Young- 3 corresonding-ly for normal pen- 



8 P 

 tane. At the critical volume the values of the y=- obtained 



, at constant volume becomes identical with the value of the 



SP 

 : ^p denoting the increase in vapor pressure of the liquid. 



i Therefore it is possible in these three cases by comparison 



8 P 

 with the values of the -^p obtained in the above papers to 



8 P 

 letermine whether the values of the -^7=- calculated from Biot's 



iphil. Mag. [5 J, 23, 435, (1887). 

 2 Ibid, [5], 38, 569, (1894). 

 a Ibid. [5], 47, 358 (1899). 



