406 Mr. R. A. Lehfeldt on the 



in his paper (loc. cit.) tabulates the values of p/(7r A + 7r B ) for 

 different temperatures ; and this quantity, whose constancy 

 or regular changes it was his object to observe, shows 

 irregular fluctuations amounting to one per cent. That may 

 therefore be taken as the order of accuracy of the observa- 

 tions of pressure. 



The results obtained are given in the following tables : — 



[Explanation of tables : — A, B, molecular weights of 

 the pure liquids ; 7r A , 7t b , vapour-pressures of pure 

 liquids ; q, ratio of mass of A to mass of B in liquid ; 

 p, vapour-pressure of the mixture ; r, constant of 

 equation (18)]. 



Alcohol and Ether (Wiillner). 



A (Alcohol) =46; B = 74. 



r = *5. 



Temp. 7°*2. 



tt a = 24-37. 



ttb = 264-7. 



9- 

 1 



p (calc). 



183-0 



p (obs.). 

 183-0 



•5 



213-3 



215-0 



•25 



236-6 



231-6 



Temp. 16*2. 



tta=38-25. 



tt b = 379-2. 



9- 

 1 



p (calc). 

 265-9 



p (obs.). 

 261-6 



•5 



307-8 



305-0 



•25 



340-7 



329-9 



Temp. 25-5. 



7T A =66-25. 



tt b = 553-0. 



1 



p (calc). 

 394-4 



p (obs.). 

 392-7 



•5 



455*9 



448-2 



•25 



502-4 



478-0 



r='5. 



r = '5. 



The formula indicates that with ^ = -005 nearly, p is a 

 maximum and equal to 265*8 millim., or *9 millim. more than 

 the saturation pressure of pure ether. 



Carbon Disulphide and Ether (Regnault). 



A (Carbon Disulphide) = 76 ; B=74. 



Temp. 9°. tt a =190-75. tt b = 274'85. r=-79. 



q. j9(calc). p (obs.). 



1 268*7 272-7 (equal weights) 



1-385 264*6 263*8 (44 per cent, of CS 2 by volume) 

 2-936 245-1 249*1 (62 per cent, of CS 2 by volume) 



