1163 



^1 ^ , .. _ ^2 { y^i + '''2 f^ , <^1.M 



il/^», 5r.s, i -1 2737 ' K m„ V ^273 



/; = 1 : jl - 1/2 ,,^ .T.,^ (l + ^)^: X 0.406 - 

 A = 1 : 1 1 - ^/2 n., .^.^^ (l + ^) ^. X 0.406 - 



C,^\ . m,— 0.188m„ 

 273 



1 



D = — («2 ''l ^1 /l + »1 '^ ^2/2) 



CA , m -0.11 



273y ' m,+m., 



Possibly in the last formula the coefficient— might be replaced by 







a slightly ditferent one, but the uncertainty involved in this has but 



a small influence on the result. 



A difficulty in the calculation arises from the constant Cj^, which 



measures the attraction of unlike molecules. Experiments on the 



viscosity of mixtures have shown, ihat tlie influence of temperature 



may in that case, as with pure substances, be represented by means 



of a factor I 1 + tt, ); '•I'f tlie coustant C in this factor is not iden- 

 tical with the 6'i2 in the above formulae, for in the viscosity of a 

 mixture not only the attraction of unlike molecules but also (hat 

 between like molecules plays a part. If the observations could be 

 represented by a rigorous theoretical formula, the various attractions 

 could be separated and thus the 6^3 in question determined. As this 

 is not the case, however, an estimation has to be resorted to ; it 

 seems simplest to rake for C^.^ the value which holds for the mixture 

 of composition 1:1 as a whole : fortunately a small change in C'l, 

 does not involve more than a small change in the result. 



For the mixture of equal parts of CO^ and H^ {n^=?i.i=^hi), 1 have 

 calculated from Breitenbach's experiments ^) C\., = 116.2. 



The molecular diameters Aj and .So were found from tlie viscosities 

 of the pure components at 0° using the formula 



1) P. Breitenbach, Wied. Ann. G7; p. 803, 1899. 



