72 



THE ROYAL SOCIETY OF CANADA 

 Table II 



Owing to the difficulty of securing sufficient vapour density 

 around arcs in vacuo it was found impossible to obtain any reversals 

 in the arc spectrum so that no conclusions can be made from the 

 point of view of absorption about the series of selenium in this region 

 of the ultra-violet. 



Summary 



1. Thirty new lines have been recorded in the selenium arc 

 spectrum between A = 2300 A.U. and A = 1400 A.U. 



Admiralty Physical Laboratory, 

 South Kensington. 



14th April, 1919. 



