Laws of Molecular Force, 29 



The value of 2F e for T1 2 C0 3 is probably too small because 

 the melting-point given for this compound seems to be too 

 low. Confining our attention to the Na and K data, which 

 are the best, we get for F/2 for C0 3 the value 2*8 as against 

 3*3 by the surface-tensiou method, and for S0 4 F/2 is 43 as 

 against 4*0 in the surface-tension method. This value 4*3 

 gives for F in Ag a value 3*6, while 3*4 was the value de- 

 rived from the nitrate, in Tl F is 4'9 from the sulphate as 

 against 4*2 from the nitrate ; the values for the metaphos- 

 phates again show that Na and Ag have nearly equal values 

 for F, and that for P 2 6 F/2 is 7'4, while 6*7 was the value 

 found by the former method. 



We advance to a higher degree of molecular complexity 

 when we take up the nitrates of the dyad metals of type 

 R(N0 3 ) 2 ; here Mc is 41*6, and as there are three radicals in 

 the molecule k is 1/3, and thus 



»P/=5-8xl0- 4 3^|j(M/p)TM-. . . . (17) 



It happens that this equation, when applied as in the next 

 Table to the nitrates of Ca, Sr, and Ba, gives values for 

 (M 2 /)* which are nearly the sum of F for Ca and twice F 

 for N0 3 , and so on, so that the effect of valency does not 

 appear here ; but before remarking further about this let us 

 take the data : — 



Table XXII. 



Nitrates. Chlorates. 



Ca. Sr. Ba. Ba. 



T 834 918 866 687 



M/p 69-5 719 809 (97) 



(M 2 *) 1 13-0 142 14 9 14-7 



With F for N0 3 as 3'6, for Ca as <3'4, Sr 7 '4, and Ba 

 8*4 (see Table XVII.), we get for the nitrates 13*6, 14*6, 

 and 15*6, when valency is ignored, and these values are in 

 substantial agreement with those just given in the Table. 

 The question arises whether this is merely the fortuitous 

 effect of some peculiarity of these nitrates not taken account 

 of in equation (17), or whether it is due to the fact that the 

 valency of the atom which determines the type exercises less 

 influence as the radicals to which it is united become more 

 complex ; or, in other words, do the compounds of the metals 

 when complex enough tend towards obeying the same law 

 for (M 2 /) 5 as holds in the carbon compounds ? The question 



