514 



Frederick Guthrie on some Thermal and 



temperature of nearly 2° C. lower ; and having prepared fresh 

 examples of the liquids with equal care, and having changed 

 the barometer- tubes, I found : — 



Table LXVI. b. 



Vapour-tensions of Mixtures of Chloroform and Bisulphide 

 of Carbon. 







T=13°*8C. 





Chloroform, 



Bisulphide 

 of Carbon, 



Mercurial 

 depression, 

 in millim. 



Liquid 

 above 



Vapour-tension, 

 in millim. 



per cent, 

 by weight. 



per cent, 

 by weight. 



mercury, 

 in millim. 



of mercury, 



at 13 c -8. 







100 



259-5 



830 



251-6 



5 



95 



2660 



1081 



255-7 



10 



90 



260-3 



910 



251-5 



15 



85 



258-5 



85-2 



2503 



20 



80 



255-5 



70-9 



248-6 



30 



70 



252-5 



70-9 



245-4 



40 



60 



248 



73-3 



240-6 



50 



50 



243-5 



83-0 



2350 



60 



40 



236-1 



78-2 



227 8 



70 



30 



220-3 



595 



2140 



80 



20 



210-7 



76 5 



202-3 



90 



10 



199-1 



78-1 



190-4 



100 







1700 



1132 



158-4 



Spec. grav. of bisulphide of carbon, 1*23 • of chloroform, 1*49. 



The result seems, then, to be this : The vapour-tension of 

 bisulphide of carbon at 16°*0 is 264" 8 millim., at 13°*8 it is 

 251*6 millim., both referred to mercury at those temperatures. 

 Of chloroform the vapour-tensions at these two temperatures, 

 also referred to mercury at the same temperature, are 169*2 

 and 158*4. A very great increase of the vapour-tension is 

 brought about by mixing a very little bisulphide with the 

 chloroform ; a little rise is brought about by mixing a little 

 chloroform with the bisulphide. The graphic interpretations 

 of the two Tables LXVI. a and LXVI. b are shown in curves 

 C and D, fig. 6. 



§ 279. If we could find two liquids showing neither con- 

 traction nor expansion when mixed, and neither liberating 

 nor absorbing heat, the vapour-tension of a mixture of such 

 liquids should be expressed by the equation 



Vt( ma+n b) = Vt a + 



mafytb — vtg) 

 ma 4- ?ib * 



where generally vt s means the vapour-tension of the liquid s, 

 and where a and b are the liquids and m and n their respective 



