542 Dr. R. 1). Kleeman on the 



and v x the volume displaced by the piston c and v 2 that dis- 

 placed by the piston d. v x and v 2 are given by the 'equations 



/ , BY ?iA 



( $v w s \ 



where p± and p 5 denote ihe densities o£ the saturated vapours 

 o£ molecules 1 and 2 respectively. Now Lw 1 =L Wl / — L*/', 

 where L Wl ' denotes the internal heat o£ evaporation of ^ 

 firms. o£ molecules 1 from the mixture into a vacuum and 

 Lfi," the heat of evaporation of ?i x grms. of the saturated 

 vapour of molecules 1 into a vacuum. Similarly, 



L« = L;?„ — L?z c 



•2 



If 



Now we have seen that expressions for L« x ' and Lw a are at 

 once obtainable from the law of attraction between mole- 

 cules. The values are 



and 



where 

 and 



M, 



H2= * 3 (2 , 'fa) 



c?7, and ## denoting respectively the distances of separation 

 of the molecules in the vapours of molecules 1 and 2. 

 Since Lw l w 2 = L Wl , + L W3 ' we have for the heat of mixture by 

 means of the above equations the expression 



+ V^mJ L* T irJ + i ^r^ ffi/ L T zr -*J 



