on the Fluidity of Mixtures of Miscible Liquids. 663 



but whatever formula is used it is exceptional to obtain 

 values agreeing with experimental data. 



Mixture formulae based on percentages by weight of the 

 constituents of the mixture have been used by Wijkander *, 

 Linebarger t, Thorpe and Rodger {, and Bingham §. 

 Mixture formulae based on percentages by volume have been 

 used by Thorpe and Rodger, Lees ||, and Findlay If. 

 Viscosity formulae have been most used, but Bingham 

 advocates fluidity formulae on account of the parallelism 

 between conductivity and fluidity. 



The specific volume = fluidity formula of Batschinski** for 

 pure liquids, which has a rational basis and which gives 

 excellent agreement with experiment, seems to give support 

 to the use of a volume = fluidity formula for mixtures. 



In this communication the fluidity formula of Lees is used, 



F = Y 1 F 1 + V 2 F 2 , 



where V x , Y 2 are the volumes of the two constituents in 

 1 c.c. of the mixture, and F, F 1; and F 2 are the fluidities of 

 the mixture and the constituents. 



As the composition of mixtures is usually expressed in 

 percentages by weight, the formula is not convenient in the 

 form given by Lees : a more convenient form is 



lOO^F = m 1 v 1 F 1 + ??2 2 t , 2 F 2 , 



where m x and m 2 are the perceniages by weight of the con- 

 stituents in the mixture; 



r x and v 2 the specific volumes of the constituents in the 

 mixture, and v the specific volume of the mixture; 



¥ 1 and F 2 the fluidities of the constituents in the 

 mixture, and F the fluidity of the mixture. 



It is suggested that the above formula should hold for 

 all mixtures of chemically indifferent, non-associated liquids, 

 if Vi and r 3 are understood to be the specific volumes assumed 

 by the constituents of the mixture in the mixture, and not 

 their specific volumes as pure liquids at the same temperature, 

 while Fj and F 2 are the fluidities corresponding to the 



* Lwuls. Phys. Satlsk. Jubelskrift. 1878. 

 f Amer. J. Sci. (4) ii. p. 331 (1896). 

 X J. C. S. 1897, Trans, p. 360. 

 § Amer. Chem. Jour. xxxv. p. 195 (1906). 

 || Phil. Mag. (6) i. pp. 128-147 (1901). 

 % Zeit. Phys. Chem. Ixix. p. 210 (1909). 

 ** Zeit. Phys. Chem. lxxxiv. p. 643 (1913). 



