30 Mr. William Sutherland on the 



is merely raised in connexion with the results of the last 

 table, to which by themselves little weight need be attached, 

 but we will return to the matter shortly in connexion 

 with the organ ometallic compounds. Meanwhile we will 

 take the data for a few compounds of tri- and tetrabasic acids 

 with which to gain some more knowledge of the influence of 

 the basicity of an acid radical on its attracting-power ; these 

 compounds are Li 3 P0 4 and Ag 3 P0 4 , the orthophosphates of 

 Li and Ag, Na 4 P 2 7 and Ag 4 P 2 7 , the pyrophosphates of Na 

 and Ag, and along with these will be taken Na 2 B 4 7 , the Na 

 salt of the dibasic pyroboric acid. 



For the orthophosphates Mc = 41, for the pyrophosphates 

 63, and for the pyroborate 63; in the orthophosphates there 

 are four radicals to the molecule, so that £=1/4, so for the 

 pyrophosphates k=l/b, and for the pyroborate & = l/3: thus 

 the equation (13) becomes for the orthophosphates 



M 2 /=5-8xl(T 4 x j^i^ (M//9)TMs . . . (18) 



and so on. To reduce (M 2 Z)' to SF e , we must divide it by 3 T * 

 for the orthophosphates, by 4 T * for the pyrophosphates, and 

 by 2 T * for the pyroborate ; and thus we get 







Table XXIII. 









Li 3 P0 4 . 



Ag 3 P0 4 . 



Na 4 P 2 7 . 



Ag 4 P 2 7 . 



Na 2 B 4 T 



T 



1130 



1122 



1161 



858 



834 



M/p... 



(50) 



(68) 



109 



113 



85 



2F„... 



5-8 



7-5 



85 



8-0 



120 



With 2*4 as the value of F for Li, and 3 4 for Ag, we get that 

 for P0 4 , F/3 is 3*4 and 4*1, or in the mean 3*7 ; so with 3*5 

 for Na and 3*4 for Ag, F/4 for P 2 7 is 5'0 and 4*6, or 4*8 in 

 the mean ; so also F/2 for B 4 7 is 8' 5, the value found by the 

 surface-tension method for F/2 in B 4 7 was 7:2. and for F/4 

 in P 2 7 was 4*1 (see Table XL), which would be obtained 

 on dividing the values just found by 1*2. 



We are now in a position to make the same comparison 

 between the values of F for a large number of acid radicals 

 in inorganic compounds, and the volumes B of these radicals, 

 as was made in connexion with organic compounds. In the 

 following Table the first row contains the value of F as given 

 by the surface-tension method in Table XL, in the second 

 row the values of F given by the Kinetic Theory of Solids, in 

 the third the mean of these two sets of values, in the fourth the 



