82 JOURNAIv O^ THE 



^^roups to which they belong- and a wider divergence 

 from the next g-roup to them. From them can be de- 

 duced the properties for the remaining elements of 

 the group. Thus in group I Li is the bridge or group 

 element and Na the t3^pe. From this type two lines of 

 elements diverge, averaging* three to the line. These 

 triads would of course be changed into tetrads or pen- 

 tads 1)}^ the discovery of more elements. No impor- 

 tance is attached to the fact that at present they are 

 in threes. There is a distinct increment for each line 

 of elements. These can be averaged thus; Fig. 1 rep- 

 resenting the arrang-ement and increments for the first 

 three groups, and hg, 2 the arrangement in the last 

 four groups, the increments varying slig-htly. These 

 increments could be averaged in all except one case, 

 and the agreements with known atomic weig^hts would 

 be close enough to admit of the easy arrang-ement of 

 the elements in the prescribed order. Naming the 

 triads Right Triad and Left Triad respectively we 

 find that thcsj averaged increments would be as fol- 

 lows: the increment from group to t3^pe element is six- 

 teen; from the type to the first element in the Left 

 Triad iL. T.) is IS ; to second element L. T. is 63 ; to 

 the third is 112 ; — to the first element to the Right 

 Triad (R. T.) is 41- ; to the second R. T. is 88; to the 

 third is 177. 



