330 



Mr. W. Hibbert on the Gladstone 



these quantities give much larger figures. The ratio 



actual volume of molecules 



apparent volume of liquid 

 is generally estimated to be about 0*2 or 0*3 ; that is, about 

 four times greater than the value now found by the new 

 hypothesis. 



To this objection it may be replied : — 



1. Prof. Tait has expressed the opinion that " the estimates 

 hitherto made can hardly be called even rough approximations. 

 But probably the particle does not occupy so much as 5 per 

 cent, of its share of the whole content " *. This estimate is 

 not far from the 6 per cent, yielded by the foregoing cal- 

 culations. 



2. It will be suggested at a later stage that the expressions 

 which give 0'2 or 0*3 for the ratio /3/v probably measure, 

 not the molecular volume itself, but that part of the apparent 

 volume which may be called the molecular domain. 



Postponing further consideration of this argument, we may 

 inquire whether the value of {3 is dependent on the particular 

 temperatures employed in the observations. That is to say, 

 presuming that it is a measure of molecular volume, does it 

 show any change in value at higher or lower temperatures ? 

 Very few series of observations are accurate enough to stand 

 the severe test imposed on them by an attempt to answer this 

 question. Of the few that seem suitable, I shall give two 

 examples, taken from the work of Ketteler f. From these it 

 will appear that the answer varies, carbon disulphide showing 

 a constant value for ft at different temperatures, while water 

 gives a diminishing value as the temperature rises, 



Carbon Disulphide, CS 2 . 



Temperature. 



v. 



f*D- 



(3. 



(a*-i) (•-«. 



o 



-20 



0-75582 



1-65950 



00476 



0-46879 



-10 



076442 



1-65158 



00476 



0-46878 







077314 



1-64375 





046874 



10 



0-78207 



1-63593 



0046 



0-46872 



20 



0-79131 



1-62806 



0-046 



046873 



30 



0-80093 



1-62004 



00464 



0-46871 



40 



085515 



1-61187 



0-0459 



0-46871 



* Tait, ' Properties of Matter 

 t Ann. Phys. Chem. xxxv. p. 



