38 Mr. William Sutherland on the 



value simply related to that of the main family : thus in the 

 first family the range in the value of the ratio is only from 

 2*9 for Li to 2*6 for Cs, with a mean value 2' 7, of which the 

 value for Cu and Ag in the subfamily is a quarter. In the 

 second family the ratio is constant from Be to Ba with a 

 value 1/0, but the mean value 1*3 for Zn and Cd in the sub- 

 family is greater than that of the main family, which is in 

 strong contrast to the behaviour of the copper subfamily, and 

 may have some significance, as will be seen presently ; the 

 distinct manner in which Hg separates itself with a value 3 

 should be noticed. In the third family there are only two 

 members, Al and La, which both have the same value for the 

 ratio, *9, and in the subfamily Ga has 3 times this value, in 

 which respect it is similar to Hg, and In has double the value 

 of the main family, Tl has perhaps 1*5 times that of the main 

 family. In the fourth family there is only one main repre- 

 sentative Ce with a value *75, of which that for Sn is exactly 

 double, as was the case with In and the third family; the 

 value for Pb appears, like that of Tl, to be 1/5 times the value 

 of the main family. In the fifth family a certain arbitrari- 

 ness in our separation into main and sub-families becomes 

 apparent, because P, As, Sb, and Bi have the close relation- 

 ships of a main family; Di, which is the only metallic repre- 

 sentative of the fifth family, has a value '62 for the ratio, of 

 which those for As, Sb, and Bi are double, and that for P is 

 again double those for As, Sb, and Bi. In the sixth and 

 seventh families, where the metallic character disappears, re- 

 gularities in the ratio (M/p)/M 2 l disappear, but in these non- 

 metallic elements the tendency is towards M/p being pro- 

 portional to (MHy and not to M 2 Z. In the eighth family 

 the ratio (M/p)/M 2 / has a mean value *41. 



The second point of importance brought out by Table XXIX. 

 is that the ratio (M/p)/M. q l for each main family exhibits a 

 remarkable relationship to the valency of the family when 

 the main family is metallic. This is shown in the next table, 

 where the first row contains the valency of the family, the 

 second the value of the ratio (M/^)/M 2 / for the family, and 

 the third the product of these two. 



Table XXX. 



Valency of family 1 2 



Eatio 27 10 



Froduct of valency and ratio ... 2 - 7 2-0 



This table shows that if n is the valency, or perhaps it is 

 safer to say the order of the main family, then n(M./p)/M. 2 l 



3 



4 



5 



8 



•92 



•75 



•62 



•41 



2-8 



30 



3-1 



33 



