176 Journal of the Mitchell Society. [Dec. 



Dr. Young- gives 194.45° as probably very nearly the true 

 critical temperature, and 3.814 as the true critical volume of 

 a gram. By interpolation of the results given by Profs. Ram- 

 say and Young- (Phil. Mag*. May, 1887, p. 441) for the equa- 



SP 

 tion P = bT — 0, the true value for the -^ at this volume 



8 P 

 appears to be 436. Thus the -«-=- from Biot's formula at the 



critical temperature is about ten per cent, too low, an amount 

 which is not quite sufficient to explain the decrease in the 

 value of /*' at the hig-her temperatures. But above 180° C, 

 owing- to hydrolysis of the methyl salicylate used as a heat- 

 ing- jacket, the data is somewhat uncertain. 



It should be noticed that equation 16 of the present paper 



8 P 

 gives 441.9 as the value of the y7p-at the critical temperature, 



a result which agrees well with the value 436 given below, 

 thus confirming what has been said as to the accuracy of 

 that equation. 



November 1, 1904' 



