on the Fluidity of Mixtures of Miscible Liquids. 667 



w », 



In this case, — = 0*5727 ; 



Vl 



at 0° C., ^ = 0-5535, 



v\ 



at40°O., -' = 0-5544, 



V 2 



i, £., at the same temperatures the specific volumes and the 

 co-volume are not in the same ratio for the two liquids. 

 A change in volume is to be expected, and is actually found. 

 On the hypothesis that in any mixture of these two liquids 

 the free space per unit of co-volume becomes the same for 

 both kinds of molecule, the specific volumes taken up by 

 each liquid in any mixture can be calculated. 



Let v x be the volume taken up in the mixture by 1 gram of 

 methyl iodide, and io 1 its co-volume ; 

 v 2 the volume taken up in the mixture by 1 gram of 

 carbon bisulphide, and io 2 its co-volume. 

 Let v be the specific volume of the mixture. 

 Let m± be the percentage by weight of methyl iodide. 

 m 2 be the percentage by weight of carbon bisulphide. 



Then ?W 2 , (1) 



10! W 2 



100 v = 1)1^1 + m 2 v 2 (2) 



The values of the unknowns v x and v 2 can be found by 

 substitution. 



By substituting these values in the Batschinski equations, 

 the fluidities of each constituent in the mixture can be 

 found. 



The value of the fluidity for the mixture can then be found 

 from the formula 



100 v¥ = m l v 1 F 1 + m 2 v 2 F 2 , 



and compared with the experimental value. 



The following table gives the calculated and Thorpe and 

 Rodger's experimental values for five mixtures at different 

 temperatures, and shows that the calculated values agree 

 with the experimental values within the experimental error. 



Ether and chloroform, a third pair of liquids investigated 

 by Thorpe and Rodger, were shown by Dolezalek* to combine 



* Zeit. Phys. Chem. lxxi. p. 191 (1910). 



