262 Classification of the Elements. 
cies of Series III have always been recognized. snug 
Viewing the arrangement horizontally, the three Divisions A, 
at the top of the series, include the Perissads, or those elements 
the ratios of whose combinations are by odd numbers, as 1:1, 
: 8, 2:38, ete.; while the three Divisions B, across, include the 
Artiads, or those whose combinations are by even numbers, as 
_Again, the Tin Group in Series I is in the same horizontal 
division with the Carbon-Silicon Group in Series IT. 
relations of the two are thus recognized; and, also, by the at 
rangement in distinct series, the actual diversity ee to their 
ith Fe to form with oxygen a sesquioxyd, closely isomorphous 
nation of two codr 
silicates which have 
‘as mutually illustrs 
