1102 



/?, ± ///•. then the particilar integral counting donble does belong 

 again to £" = ; etc. 



Finally V^ (/=0) may possess a double space, which then is 



common to the two polar spaces - i= 0, ^ = (ct. § 5). Every 



OH ov 



/?3 ± uv cuts this double space along a curve, and every rt' contains 

 a double curve, the latter of which fill the whole space Rxy, ; the 

 result of the elimination K lisappears now identically. 



Observation. Following up this method, and without en- 

 countering other difficulties but those which arise from the increasing 

 number of dimensions, one can obtain an insight into the singular 

 solution of the partial differential equation of the first order with 

 an arbitrary number of independent variables. 



Physics. — "jf%f (lifi'u.iio/i-coef/icient of (jases and the viscosity of 

 ijas-mixtures\ By Prof. J. P. Kuenen 



(GommunicalL'd in the meeting of Mareh 28, 1914). 



In a j)revious communication ') on the diffusion-coefficient D of 

 gases it was shown, that the contradiction between 0. E. Meyer's 

 theory on the one hand and that of Maxavetj.-Stefan-Langevin on 

 the other can be largely removed by taking into account 'm the 

 former theory the persistence of molecular movement. By doing this 

 the limiting values for the two components, i. e. for n^ = and 

 n„ = 0, become equal., which involves a much smaller change in B 

 with the composition of the mixture than according to the incomplete 

 theory, while the second theory mentioned makes the coefficient 

 entirely independent of the composition ; observation also gives only 

 a small variation of D. 



[n order to further compare the im[>roved theory with observation 

 I have calculated D for two pairs of gases viz. carbon dioxide-- 

 hydrogen and argon- helium, which seemed specially suitable for 

 this test owing to the great difference in the molecular masses. For 

 this purpose it is necessary to give a further modification to the 

 formulae in order to express the influence of the mutual attraction 

 of the molecules: in the former theoretical paper this infiuence had 

 to be left out of account, seeing that in Stefan's theory the molecules 

 are likewise regarded as free from attraction. 



Using Sutherlat^d's well-known formulation of the attraction by 



of a factor ( 1 -|- 7,) the formulae become for 0°(7'=273). 



means 



1) J. P. Kuenen, Proc XV p. 115^. 1913. 



