346 Mr. Gervaise Le Bas on 



The chief point to be noticed other than the approximate 

 1 T K . 

 constancy o£ vvy p^ * s the gradual increase of this relation 



from pentane to octane. This evidently corresponds with 



the gradual diminution of ~m™ in the same direction, for if 



K 



the two be multiplied the products which represent the ratio 

 «v are approximately constant. These are : — 9*65 for C 5 H 12 , 

 9-688 for C 6 H lt , 9'67 for C 7 H 16 , and 9'78 for C 8 H 18 . It is 



p y 



thus concluded that the variations in the values of f K 



K 

 P r 



are due to the factor t^-. 



The Untt-stere Theory in the Light of Molecular 

 Refractions. 



The law of corresponding states implies the fact, that the 

 apparent volumes of liquids under coincident conditions are 

 measures of the space actually occupied by the molecules. 

 There should therefore be a proportionality between, their 

 apparent volumes under the above conditions, and their 

 molecular refractions as found by means of the Lorenz and 

 Lorentz formula. 



If u represent the fraction of the space actually occupied 

 by the molecules, then this formula supplies the relation 



_/x 2 -l_R 



U ~ ^ 2 + 2~V' 



jjl representing the index of refraction for light of infinite 

 wave-length. It will be sufficient to refer the refractions to 

 the D sodium-line. Then 



_ ^-i _n v 



The volumes V of the four hydrocarbons pentane, hexane, 

 heptane, and octane at corresponding pressures are referred 

 to. Under these circumstances the ratio u is the same for 

 the substances now being considered. 



