100 Mr. J. J. Waterston on certain Thermomolecular 



volume 2'44. I may add that the volume computed for —274° 

 is 0*828, nearly one- third of the maximum. 



Chloroform treated in the same way (but leaving out the 

 highest observation of X, which is quite out of the line of the 

 others) gives 268° as the temperature when C = 0. The com- 

 puted volume at that point is 2*02. The transition temperature 

 observed was 266° (§ 29), and maximum volume 243. The 

 volume computed for —274° is 0-847. 



Sulphide of carbon treated in the same way gives transition- 

 volume 2*15, the observed being 2'22, and at —274° the com- 

 puted is 0-852. 



These computations all tend to show the probably simple 

 relation between liquid molecular volume and cohesion-integral, 

 — the absolute value of the increment of the one having always 

 the same ratio to the absolute value of the decrement- of the 

 other in the same liquid and in the same class of liquids (where 



- has the same value). 



§ 50. In liquids, such as chloroform and sulphuric ether, 



which are not related in molecular volume but have —j— common 



k 



to both, the following computation suggests the question as to 



whether the force required to effect the same absolute increase of 



volume (or, in other words, the heat-force rendered latent) is 



proportional to the molecular weight or vapour-density. One 



ounce of ether absorbs 16'25 unities of heat in expanding from 



0° to 100° ; 1 cubic foot of it weighs 736 oz., and thus absorbs 



11960 unities in expanding from 0° to 100°, during which its 



volume is augmented from 1 to 1*2 cubic foot. 



One ounce of chloroform absorbs 13-25 unities of heat in 



expanding, so as to augment its volume from 1 to 1*2. 1 cubic 



foot of chloroform weighs 1525 oz., and thus requires 



1525 x 13-25 = 20206 unities 



to increase its liquid volume from 1 to 1 # 2 cubic foot. Now 

 mark the ratio 11960:20206 = 37:62-5, which is nearly the 

 ratio of the respective values of a> } viz. 37 : 60; that is, nearly, 



considering the difficulty of obtaining ~- exactly. 



A cubic foot of the sulphide of carbon at 0° requires 

 15-5 x 1293 = 20041 unities to become 1-2 cubic foot. This is 

 nearly the same amount as chloroform and the three halogen 

 ethers, although the relation of molecular volume is not so 

 simple. 



§51. The following Table contains the thermomolecular con- 



