in vacuo and in Gases. 



19 



Second class. — Binary mixtures of volatile substances which dis- 

 solve each other in larger or smaller, but not unlimited pro- 

 portions. 



It is very difficult to make mixtures of substances which come 

 in this category. I have only operated upon mixtures of aether 

 and water. They gave the following results : — 



In this case the mixture, far from giving a vapour possessing 

 a tension equal to the sum of the individual elastic forces of the 

 separate substances, scarcely presents that of the sether alone. 



Third Class. — Binary mixtures of liquids mutually soluble in 

 every proportion. 



This class includes the most numerous binary mixtures. I 

 have operated upon three mixtures in various proportions of sul- 

 phuret of carbon and aether, two liquids which are particularly 

 adapted to investigations of this nature, as they both possess 

 vapours of considerable tensions at low temperatures : — 



Upon two mixtures of chloride of carbon, C 2 CI 6 , and sulphuret 

 of carbon ; and 



Upon a mixture of benzine and alcohol. 



