Constituents of certain Mineral Substances and Waters. 447 

 FIG. 2. 



Floor of Tunnel. 



We proceeded with the examination of the gases immediately on 

 our return to London. The gases were transferred to a glass gas- 

 holder containing potash solution, and circulated over red-hot mag- 

 nesium and copper oxide. The residual gas was pumped out of the 

 circulating apparatus, and sparked with oxygen over potash to 

 remove final traces of nitrogen. 



Preliminary Spectroscopic Examination of the Gases. 



Raillere. Argon and helium, helium strong. 



Des CEufs. Argon, with less helium. 



Espagnol. Argon, with helium ; the yellow and green helium lines 

 very distinct, with jar and spark-gap. 



Caesar. Argon, with a little helium. 



The tubes were carefully compared with normal argon and helium 

 tubes, but no new lines could be detected. 



An attempt was made to separate the gas into its constituents by 

 taking advantage of their relative solubilities. A measured quantity 



