ELISHA MlTCHElvI. SCIENTIFIC SOCIETY. 



83 



Fig. I. 



o 



I 



o 



16 4 1 I 



I 

 o o 



4 6 4 5 



Fig, 2, 

 o 



I 

 i 



I 16 



i 



o 



I 2 4 5 



o o 



4 3 4 6 1 



i 

 o 



o o o o 



The one exception is in the increment from Type to 

 III Iv. T. from g-roupIV to VII. Instead of being- 112 

 this is 141. 



To the right of Group VII we have three triads 

 which have nearly the regular increments belonging to 

 the Right Triads, namely, 47 and 88. They are without 

 any type element, it seems most likely that they be- 

 long to one group. The Group element would have an 

 atomic weight of 21 and the Type one of 37. 



The arrangement in the table then is partly one 

 based upon regular increments in the atomic weights, and 

 since these are so poorly known, partly upon our knowl- 

 edge of the chemical properties of the elements. When 

 it is recalled that about one half of the atomic weights are 

 imperfectly known it will be evident that these aver- 

 aged increments are ap^Droximations only. It is impos- 

 sible to bring out such perfect symmetry as obtains in 

 the homologous series in organic chemistry. And 

 yet these groups should be something of the same 

 kind. Following the analogy to the organic hydrocar- 

 bons a little further, may not the existence of a'l ek- 

 ment in two different conditions as to valence, &c., as, 



