1895.] 



On tl\e neic Gas obtained from Uraninitfl. 



fi7 



Yellow 



Argon-tube. 

 Absent. 



Helium-tube. 



Green 



Green-blue . . 



Blue 



Blue-violet . . 



Violet 



7 lines. 



{5 lines. 

 Absent. 

 Absent. 

 Absent. 



{3 lines, strong. 

 2, fairly strong, 

 f Absent. 



I Absent. 

 Violet pair. 

 { Single line. 



Triplet. 

 I Triplet. 

 Pair. 



Brilliant. 



7 lines. 

 5 lines. 

 Faint. 

 Brilliant. 



8 lines. 



Barely visible, if in- 

 deed present ntall. 

 2, fairly strong. 

 Bright line. 

 4 bright lines. 

 Violet pair. 

 Single line. 

 Triplet. 

 Triplet. 

 Pair. 



W = 587-49. 



(the helium line, D 3 ) 



Equal in intensity. 



> 



In helium only. 



Equal in intensity. 

 } In helium only. 

 Equal in intensity. 



It is to be noticed that argon is present in the helium-tube, and 

 by the nse of two coils the spectra could be made of equal intensity. 

 But there are sixteen easily visible lines present in the helium-tube 

 only, of which one is the magnificent yellow, and there are two red 

 lines strong in argon and three violet linen strong in argon, but barely 

 visible and doubtful in the helium-tube. This would imply that atmo- 

 spheric argon contains a gas absent from the argon in the helium- 

 tube. It may be that this gas is the cause of the high density of 

 argon, which would place its atomic weight higher than that of 

 potassium. 



It is idle to speculate on the properties of helium at such an early 

 stage in the investigation; but I am now preparing fairly large 

 quantities of the mixture, and hope to be able before long to 

 give data respecting the density of the mixture, and to attempt the 

 separation of argon from helium. 



(Note added June 14. It is now practically certain that the pre- 

 sence of so many of the argon lines in the helium spectrum must 

 have been due to the accidental introduction of air. But there still are 

 coincidences, chiefly in the red lines, which would justify the suppo- 

 sition that there is some constituent common to the two gases.) 



II. " On the new Gas obtained from Uraninite. Preliminary 

 Note." By J. NORMAN LOCKYEK, C.B., F.R.S. Received 

 April 25, 1895. 



On the 28th of March, Professor Ramsay was so good as to send 

 me a tube containing a new gas obtained by him from uraninite 

 (cleveite), showing a line in the yellow which was stated to be of the 



