the Unit-Stere Theory. 345 



The above tables show that : — 



(a) Both the values of the ratio V/W and those o£ V/V K 

 diminish from pentane to octane at the corresponding 

 temperatures. 



(6) The deviations from the additive law and the law of 

 corresponding states are in the same direction and 

 are about the same fraction per cent, of the whole. 

 These facts are additional evidence in favour of the 

 close mutual dependence of the two laws. 



Application of the 4 : 1 rule to the Critical Coefficient — £. 



Young has shown that the following relation is approxi- 

 mately true for the most various substances 



-^ = ^ = a const. C. 



since 



V, 



T 

 Op . 



(loc. cit.) ; 



•p?. — The critical coefficient of Gruye (Ann. Chim. et Phys. 



K 



1890, xxi. p. 206) is subject to similar additive relations to 

 those found from a consideration of V K . 



The following Table gives the critical coefficient for the 

 four hydrocarbons (column 5), the pressures being expressed 

 in centimetres of mercury. 



1 T 



Column 6 shows the values of the ratio ^ ~ and column 8 



those of ^JF 



XIX. — Table showing the proportionality between ~ and 

 W for the Paraffin Hvdrocarbons. k 



Compound. 



W. 



**• 



T K - 





1T K 



wp K - 



Vk- 



I 



Pentane, C 3 H 12 ... 

 Hexane, OgH^... 

 Heptane, C T H 16 ... 

 Octane, C 8 H 18 ... 



32 

 38 

 44 

 50 



2510 

 2251 

 2041-5 



1873-4 



470-2 

 507-8 

 539-9 

 569-2 



•1873 

 •2256 

 •2645 

 •3038 



•00585 

 •00594 

 •00601 

 •00608 



309-2 

 366-3 

 425-7 



488'9 



1650 

 1631 

 1609 

 1609 



