410 Scientific Proceedings, Royal Dublin Society. 



Finally it was found that the diameter was in most eases very slightlj' 

 curved, and the critical densities were recalculated by means of the formula 



St = Sf^ + at + f5i~. 



In conclusion, I desire to express my sincere thanks to Dr. J. E. Mills, to 

 whom I am in many respects deeply indebted. 



In the course of his laborious and long-continued investigations on 

 " molecular attraction,"^ in which, among other things, he discovered and 

 proved the truth of the important relation that for any given substance 



L- JS, 



= constant at all temperatures [where L - -fc'i is the internal latent heat of 

 vaporization, and d and D are the densities of liquid and saturated vapour]. 

 Dr. Mills has made a most careful and complete examination of the data 

 published in my original papers. 



The investigation necessitated the calculation of the heats of vaporization 

 of the thirty substances at the temperatures given in the tables ; and Dr. Mills 

 has very kindly furnished me with these values, recalculated where necessary 

 from the revised data for pressures and volumes of saturated vapour ; and he 

 has also sent me the recalculated densities of saturated vapour. 



I am also indebted to Dr. Mills for the Biot constants for methyl acetate, 

 propyl formate, ethyl acetate, methyl propionate, and propyl acetate, and for 

 the recalculated vapour-pressures of these substances. 



Lastly, Dr. Mills has discovered a number of misprints, and a few errors 

 of calculation in the data published in the various papers ; and I am, therefore, 

 now enabled to make the necessary corrections. 



Description or Tables. 



In the tables at the end of this paper the following data are given : — 

 Table 1. — The constants for Biot's formula for vapour-pressures, 



logjo = a + ha* + cj3*. 

 Table 2. — The constants for the modified formula of Oailletet and 

 Mathias 



St = Sf^ + at + jit^ {+ yt^). 



The constant y is only required in the case of the three alcohols, the 

 molecules of which are associated in the liquid state. 



1 journ. Phys. Chera., vi., p. 209, 1902; viii., p. 383, 1904; viii., p. 593, 1904 ; ix., p. 402, 

 1905 ; X., p. 1, 1906 ; xi., p. 132, 1907 ; -xi., p. 594, 1907 ; xiii., p. 512, 1909 ; Amer. Chera. Soc, 

 xxxi., p. 1099, 1909. 



