1882.] -^4:5 [Chase 



Two of these eleineuts, Se and U, give adver.se indications ; tlie aggre- 

 gate ratio of fiivorable to adverse probabilities is more tlian 17173770000000 

 : 1. I have talcen ^ of Clarice's estimate for U, in order to compare it with 

 Gerber's assumed atomicity. 



Supplementary Artiad Group. 



Barker, in Johnson's Cydopoedia, gives otlier artiad elements which Ger- 

 ber places in his group of metals. In order to complete the comparisons 

 which are based upon valency they are inserted here : 



