ILLUSTRATIONS OF THE DYNAMICAL THEORY OF GASES. 397 



The proportion of these which strike particles of the first kind is 



The whole momentum of these remains among the particles of the first kind. 

 The proportion which strike particles of the second kind is 



The momentum of these is divided between the striking particles in the ratio 



M 



of their masses ; so that -., ',, of the whole goes to particles of the first 



kind, and -^f ^> to particles of the second kind. 



The effect of these collisions is therefore to produce a force 



on particles of the first system, and 



on particles of the second system. 



The effect of the collisions of those particles of the second system which 

 strike into the stratum, is to produce a force 



on the first system, and 



-t 



on the second. 



The whole effect of these collisions is therefore to produce a resultant force 



on the first system, 



(35) 



I - 



M l + Mi dx \ ' M! + M 3 



on the second, and so on. 



