_ Prof. Thomson, Further applications of positive rays, etc. 201 
| Further applications of positive rays to the study of chemical 
problems. By Professor Sir J. J. THOMSON. 
[Read 27 January 1913.] 
Tue author described the application of positive rays to the 
detection of the rare gases in the atmosphere. Sir James Dewar 
kindly supplied two samples of gases obtained from the residues 
_of liquid air; one sample which had been treated so as to contain 
| the heavier gases was found on analysis to contain Xenon, Krypton, 
_ Argon, there were no lines on the photograph unaccounted for, 
hence we may conclude that there are no unknown heavy gases 
in the atmosphere in quantities comparable with the known gases. 
~The other sample which had been heated so as to contain the 
lighter gases was found to contain helium and neon and in addition 
a new gas with the atomic weight 22, the relative brightness of 
the lines for this gas and for neon shows that the amount of the 
new gas is much smaller than that of neon. 
The second part of the paper contains an investigation of a 
new gas of atomic weight 3 which this method of analysis had 
shown to be present in the tube under certain conditions. The 
gas had occurred sporadically in the tube from the time of the 
earliest experiments but its appearance could not be controlled. 
After a long investigation into the source of this gas, it was found 
that it always occurred in the gases given out by metals when 
bombarded by cathode rays, a trace of helium was also usually 
found on the first bombardment. The metals used were iron, 
nickel, zinc, copper, lead and platinum; the gas was also given off 
by calcium carbide. Various experiments were described which 
illustrated the stability of the gas. 
