Double-Layer of Solid and Liquid Bodies. 31 9 



According to (11), the electric intensity due to the nuclear 

 doublets is equal to 



S*..- + ^(&-|*D i , • • • . (D) 



and that due to the electronic doublets, 



E e , x = — (a -.|^|)2 j . . . . (E) 



the whole intensity E x being equal to the sum o£ Eh, x and 

 E, iX for 'x\<b<a, and to E e , x for \x\>b (i. e. outside the 

 double-layer corresponding to the nuclei). For the energy 

 W per sq. cm. we get 



Taking for rc (the number of molecules per c.c.) 



n= 6*06 xlO 23 |r, 



where 3 is the specific weight of liquid hydrogen and M its 

 molecular weight (£ = 0-075, M = 2) and performing the 



calculations, we find 

 and 



.= - i " E* x ^=21, W H = } ( , *Ei fX 2*=7, 

 W,, H =i-fE,, z E H , 2 ^=24, 



whence W = W e + W H — W e ,H = 4, which is very near to the 

 experimental value of the surface-tension of liquid hydrogen 

 (7 = 2 (see Table V.)- 



When the structure of the molecule is known, the calcu- 

 lation of the surface-tension presents a very simple problem, 

 and I shall not, therefore, dwell upon it any longer. The 

 essential feature in this case is the participation of the positive 

 nuclei in the creation of the surface electric field, canting a 

 diminution of its energy. This is why the surface-tension of 

 salts is always less than that of the corresponding metals, 

 and the surface-tension of dielectrics of any composition less 

 than that or." the salts. 



In conclusion, it may be mentioned that our theory gives 

 the right dependence of the surface-tension upon the density 



