Laws of Molecular Force. 35 



radicals, because for basicities higher than one this ratio came 

 out only half the value for basicity one, which corresponds to 

 a value of F double what would be expected from other con- 

 siderations. As these facts show a characteristic influence 

 belonging to compound radicals, it will be instructive to return 

 to the case of the nitrates of the dyad metals, in which, ac- 

 cording to what we have just seen, the values of (M 2 /)* in 

 Table XXII. when divided by 2^ and reduced by 3*6, the 

 value for N0 3 , ought to leave values for F/2 for Ca, Sr, and 

 Ba which are double the values obtained from the halogen 

 compounds. Performing these operations we get for 



Ca. Sr. Ba. 



F/2 51 59 6-3 



From Table XYII 32 37 42 



The values of F/2 from the nitrates are only 1*5 and not 2 

 times the values from the chlorides ; and thus the nitrates of 

 these metals do not come satisfactorily under this principle, 

 and there are too many steps in the process of determining 

 the value of F/2 from the nitrates to enable us to fix upon a 

 probable cause of the discrepancies in these nitrates. 



With the organometallic compounds we have finished the 

 data for compounds to be discussed in the present paper, and 

 have now an opportunity to make a comparison between the 

 values contributed by the atoms of the metals to M/3 and to 

 (M. 2 iy in a molecule, though to keep it clear that in the com- 

 pounds of the metals we have had to take account of valency 

 n we will give the values of B/n and F/n in the following 

 table. There is considerable difficulty in getting the atomic 

 volumes of such atoms as P and As, because the relations of 

 the chlorides, bromides, and iodides are not consistent with 

 those of the chlorides, bromides, and iodides of the monad 

 metals ; the volumes of the lower members of the monad and 

 dyad series are also difficult to assign, being small. In the 

 case of P, As, and Sb the volumes adopted are those given 

 by Thorpe (Journ. Chem. Soc. 1880) as the domains of these 

 atoms in liquids at their boiling-points; they are therefore 

 probably too large, but not necessarily much too large, because 

 the domains of the halogens in organic compounds at their 

 boiling-points are almost identical with their limiting volumes 

 in these compounds, and also in metallic compounds. Ac- 

 cordingly the values of the limiting volumes of the atoms 

 given in the next table are only such general approximate 

 values as represent best the facts of the simplest compounds. 



D2 



