376 E. A. Hill—WNotes on Argon and Helium. 
etc. The term strong above means that each line is equally 
strong in the minerals named; thus in Group B, one of the 
lines has intensity 8 and the other intensity 10, in all samples 
of the gas except broggerite R. 
The natural inference is that each of the groups A to N 
represents one or more distinct gases, except that ” may after 
all be identical with H. The line D* occurs in Group A. 
Helium purissimum is apparently one of the most complex, and 
broggerite R one of the most simple of the five gases. By 
construing the work of other observers, as Runge and Paschen, 
with that of Crookes, these groups may be still further sub- 
divided. Apparently the gases given off by minerals of the 
uraninite type, which are loosely spoken of as helium while 
they contain helium, are very complex mixtures of gases of the 
argon and helium types containing anywhere from 4 or 5 to 11 
or more distinct constituents. 
