272 SCIENCE PROGRESS. 



observed the line at 7065 in the gas obtained from the 

 cleveite (Comptes Rendus, 17th June, 1895, p. 1 331). 



A great deal of work has been done upon these gases 

 from other points of view than those which affect their 

 cosmical relations, and perhaps I may be allowed next to 

 refer to some of the results which have been obtained by 

 myself. 



HELIUM NOT CONNECTED WITH ARGON. 



The first point is that the gas from the minerals contains 

 no argon. Dr. Ramsay in his first experiments came to the 

 conclusion that the spectra of argon and helium contained 

 many common lines ; indeed at first the observed coin- 

 cidences were so remarkable that he came to the conclusion 

 that the connection was so close that atmospheric argon con- 

 tained a gas absent from the argon seen in his helium tube. 



This statement was subsequently withdrawn, but the 

 compound nature both of argon and helium was suggested 

 by the fact that there were lines common to the two gases. 

 These lines were in the red ; one coincidence I found broke 

 down with moderate dispersion, the other yielded subse- 

 quently to the still greater dispersion employed by Drs. 

 Runge and Paschen. It may be also stated here that I have 

 not found a single coincidence between argon and any line 

 in the spectrum of any celestial body whatever. This 

 happens, as everybody knows, also in the case of oxygen, 

 nitrogen, chlorine, and the like. 



THE CLEVEITE GAS A COMPOUND. 



The first spectroscopic observations made it perfectly 

 obvious that the gas as obtained from uraninite is a mixture 

 of gases, that the gas which gives the yellow line is not an 

 isolated one, but is mixed up with other gases which give 

 other lines. 



In May I wrote as follows : — 1 



" The preliminary reconnaissance suggests that the gas 

 obtained from broggerite by my method is one of complex 

 origin. 



1 Proc. R. S., Iviii., p. 114. 



