338 



Mr. W. Hibbert on the Gladstone 



I can best illustrate this by taking a table from a lecture 

 on the " Range of Molecular Forces " delivered to the 

 Chemical Society by Biicker (Chem. Soc. Journ. 1888, 

 p. 253). 



Using Hopkinson's data, Riicker compares the values of 



K-l , fi?-l 

 and 



K + 2 



^ 2 + 2 



for five substances (K = specific inductive capacity). His 

 object is to show that the figures justify well-known theories 

 due to Clausius, Clerk-Maxwell, and others. Assumptions 

 underlying these expressions make them a measure of the 



true volume of molecules 

 apparent volume of liquid' 



though the expression " true volume of molecules " is a quan- 

 tity depending on what is better known as the " diameter of 

 the molecule," i. e. the smallest distance between the centres 

 of molecules. 



The table is quoted bodily, with an additional column to 



show the value of , this last being the factor of v in the 



square bracket of the transposed expression. 



Substance. 



Formula. 



K. 



M 2 . 



K-l 

 K+2' 



/x 2 H-2 



ix-l 



Benzol 



C 5 H 10 . 



O c H 6 . 

 C 7 H 8 . 



C 8 H 10 . 



C 10 H 12« 



2-05 

 2-38 

 242 

 2-39 

 2-25 



1-9044 

 2-2614 

 2-2470 

 2-2238 

 2-2254 



0-260 

 0-315 

 0-321 

 0-317 

 0-294 



0-232 

 0296 

 0-291 

 0-290 

 0-290 



0-245 

 0-334 

 0-333 

 0-329 

 0295 



Toluol 



Xylol 



Cvmol 





Here it is evident that there is a close agreement among 

 the three sets of figures, amply sufficient to justify further 



examination. So far as differences occur, — — is nearer 



K-l ., . /* 2 -l * 



^ ; than is -s — £• 



K + 2 ^ 2 + 2 



In pursuing this comparison I shall introduce ft, so that 



