40 Mr. William Sutherland on the 



strictly proportional to one another as in the free state, yet 

 the numbers in the third row show that the connexion between 

 the two quantities in the combined state is the simple one 



F 2 = «9B + 4'4 



while for the free atoms the relation was 



M 

 9 



™ 1 M 



Z'l o 



In the Be family we get 



Table XXXI. {continued). 



(Be family in compounds.) 



Be. Mg. Ca. Sr. Ba. 



B 10 56 8-6 106 166 



F74 4-4 7 3 10-2 137 176 



•9B+30 39 8-0 107 125 18'0 



The data of this family are affected with considerable 

 uncertainty, but the third row of numbers shows that probably 

 in compounds 



F 2 /4=-9B + 3-0, 



while for the free metals the relation was found to be 



M 2 Z = M/ / o. 



It is noticeable that the constant *9 for the Be family is the 

 same as that for the Li family. 



It is not possible with the existing data to follow this 

 interesting inquiry into the other metallic families, and trace 

 the transition from the form of relation F 2 = aM/p + b holding 

 amongst the powerfully positive metals to the form F = cM/3 

 (e being a constant) characteristic of the non-metals, and 

 apparently of some weakly electropositive metals. 



We proceed now to the surface-tension method of finding 

 M 2 Z for the metals, chiefly to draw attention again to a dis- 

 crepancy between the values of M 2 / for the free metals given 

 by the Kinetic Theory of Solids and those by the method of 

 surface-tension. This was pointed out at the end of the paper 

 on the Kinetic Theory of Solids, but it can be brought out 

 here in a more definite manner and with more interest, seeing 

 that the two methods have been proved in this paper to give 

 accordant results for binary compounds. To the gain of the 

 Kinetic Theory of Solids, the discrepancy will be largely 

 cleared up as due to molecular complexity, 



