512 



Frederick Guthrie on some Thermal and 



be quite prepared to unite as a whole with another atom or 

 molecule (compare § 267). 



§ 274. The contraction and heating attending the mixing 

 of alcohol and water have been long known. When, in § 98, 

 I described the solid combination of the two, C 2 H 6 0, 4H 2 0, 

 and called it a cryohydrate (I should now call it a sub- 

 cry ohyd rate), I did not suppose that it was only one of so 

 numerous a family as appears to be the case. In § 104 was 

 briefly described a combination of ether with water. I may 

 here mention the circumstance that equal volumes of the two, 

 when shaken together at 17°"1, rise in temperature to 18°*9. 

 Equal volumes brought together at 17°*6 in the experimental 

 tube of § 268, and agitated by a globule of mercury being 

 made to pass to and fro through the capillary opening, con- 

 tract 0*005436 of their joint volume, and require to be 

 heated to regain that volume. This contraction is probably 

 very far from the maximum, as there is no doubt a large 

 quantity of passive matter present. For the same reason, 

 the maximum liberation of heat will probably be found with 

 a less water-ratio. Where the maximum heat-liberation 

 occurs we should look for the subcryohydrate, and there also 

 for the maximum contraction. 



Vapour -tensions of Mixtures of Bisulphide of Carbon 

 and Ether. 

 § 275. Taking next an instance where expansion and cold 

 result from mixture, I give at once the numerical results as 

 to the vapour-tensions of the various mixtures. 



Table LXV. 



Vapour-tensions of Mixtures of Bisulphide of Carbon 



and Ether. 



T = 18°-88C. 



Bisulphide 



Ether 



IVTercurial 



Liquid 



Vapour-tension, 



of Carbon, 

 per cent, 

 by weight. 



per cent, 

 by weight. 



depression, 

 in millim. 



above 

 mercury, 

 in millim. 



in millim. 

 of mercury, 

 at 19° 02. 



100 







291-9 



78-1 



284-5 



90 



10 



353-3 



77-5 



346-3 



80 



20 



380-8 



75-0 



374-3 



70 



SO 



404-1 



82-8 



387-3 



60 



40 



416-5 



81-2 



410-1 



50 



50 



425-2 



80-0 



4193 



40 



60 



441-0 



90-9 



424-6 



30 



70 



434-8 



75-0 



429-8 



20 



80 



438-1 



834 



433-0 



10 



90 



437-2 



81-7 



432-5 







100 . 



4365 



81-7 



4321 



Specific gravity of ether, 0*72 ; of bisulphide of carbon, 1*23. 



