212 Mr. J. C. Maxwell on the Dynamical Theory of Gases. 



period of vibration of the most acute audible sounds ; so that even 

 in the theory of sound we may consider the motion as steady 

 during this very short time, and use the equations we have 

 already found, as has been done by Professor Stokes"^. 



Viscosity of a Mixture of Gases, 



In a complete mixture of gases, in which there is no diffusion 

 going on, the velocity at any point is the same for all the gases. 

 Putting 



2 / 9 du dv dw\ ^_ TT 

 Z\ dx dy dz)~~ ' 

 equation (122) becomes 

 frU^-M^A- ^ k ^ (2MA + 3M 2 A 2 )p 2 g 



(137) 



-A;(3A 2 -2A 1 : 

 Similarly 

 ^ 2 U=—3£ 2J 



M, + M 2 



M 2 

 Mj + M, 



k 

 M 2 + M 2 



M, 



PiQv 



(2M 2 A 1 + 3M 1 A 2 )p^ 2 



(138) 



(139) 



Since p=p 1 +p 2 and q = q 1 + q 2 , where p and prefer to the 

 mixture, we shall have 



^U=~g=-(^ + ^ 2 ), 

 where jjl is the coefficient of viscosity of the mixture. 



If we put s x and s 2 for the specific gravities of the two gases, 

 referred to a standard gas, in which the values of p and p at 

 temperature O are p and p , 



* p 6 ' 3A 2 Vi%i ci + Hjp, p 2 + 3 A 2 k 2 s 2 Gp 2 2 ' 

 where jjl is the coefficient of viscosity of the mixture, and 



(140) 



s i -f-s 2 

 F = 3A 2 (Vi + ^ 2 )-(3A 2 -2A 1 )^ 



G: 



ksc 



<6S iSq 



■*S 



(25 1 A 1 + 3« 2 A 9 ), 



ll = SA 9 s l s i {3k l k i k i +2h*A l } 



(141) 



* " On the effect of the Internal Friction of Fluids on the motion of 

 Pendulums," Cambridge Transactions, vol. ix. (1850), art. /9. 



