522 Mr. W. Sutherland on the Viscosity 



is given by the formulae 



Mi 



(2a)Xrelative)= 102%(1 + c/273) , 



1+-° 



V%=(T/273)I ^?, 



and we have seen that for compounds 



(2a) 3 (relative) =124M/3 and M/3C10- 2 =2lM 2 Z/2; 



so that with values of /3 and M 2 Z we can calculate the visco- 

 sities of substances as gases. Values of M 2 Z are tabulated 

 (Phil. Mag. March 1893), and the method cf calculating 

 them from chemical composition is also given, and values of 

 ft, the limiting volume of a gramme of the above substances, 

 are calculable from existing data by means of the characteristic 

 equation for liquids given in the same paper, or by a much 

 simplified unpublished equation which gives the same values 

 to the degree of accuracy required for the present purpose. 

 Here are the values of M, M/3, and M 2 / for the above sub- 

 stances : — 



C 2 H 5 C1. (C 2 H 5 ) 2 0. C 2 H 5 OH. H 2 0. C 6 H 6 . (OH 3 ) 2 CO. 



M 64-4 74 46 18 78 58 ' 



M/3 ...... 55-5 824 46 (near) 16 (near) 75"5 56 (near) 



M.H 27-4 40-2 17-6 6-8 43-8 31-1 



Methyl Propyl Methyl Ethyl 



CHC1 3 . OS 2 . formate, acetate, isobutyrate. propionate. 



M 119-2 76 60 102 102 102 



M/3 72 50 46 97 97 97 



MH 36-9 26-9 22-9 58"5 58-5 58-5 



With these the following values of the viscosity at 0° C, due 

 to collisions only, have been calculated, and will be denoted 

 by H to distinguish them from 7] , the total viscosity of the 

 vapour. 



2 H 5 C1. (C 2 H 5 ) 2 0. C 2 H 5 OH. H 2 0. C 6 H 6 . (CK 3 ) 2 CO. 



H ... 76-6 63-5 92 102 617 65-6 



Methyl Propyl Methyl Ethyl 



CHC1 3 . CS 2 . formate. acetate, isobutyrate. propionate. 



H ... 85-5 84-3 834 581 584 584 



With these values the part of the viscosity due to collisions 



