194 On the neiv Gas obtained from Uraninite. [June 1.3, 



The above observations were made with a battery of five Grove 

 cells ; the reduction of cells from 5 to 2 made no difference in the 

 phenomena except in reducing their brilliancy. 



Reasoning from the above observations, it seems evident that the 

 effect of the higher tension is to break up a compound, or compounds, 

 of which C, D 3 and 447 represent constituent elements ; while, at the 

 same time, it would appear that 667 represents a line of some com- 

 pound which is simultaneously dissociated. 



The unequal behaviour of the lines has been further noted in another 

 experiment, in which the products of distillation of broggerite were 

 observed in a vacuum tube and photographed at various stages. 

 After the first heating, D 3 and 4471 were seen bright, before any 

 lines other than those of carbon and hydrogen made their appearance. 

 With continued heating, 667, 5016, and 492 also appeared, although 

 there was no notable increase of brightness in the yellow line ; still 

 further heating introduced additional lines 5048 and 6347. 



These changes are represented graphically in the following 

 diagram (fig. 2). 



Fia. 2. Diagram showing order in which lines appear in spectrum of vacuum tube 

 when broggerite is heated. 



It was recorded further that the yellow line was at times dimmed, 

 while the other lines were brightened. 



In my second note, communicated to the Royal Society on the 8th 

 instant, I stated that I had never once seen the lines recorded by 

 Thalen in the blue, at X 4922 and 4715. 



It now seems possible that their absence from my previous tubes 

 was due to the fact that the heating of the minerals was not 

 sufficiently prolonged to bring out the gases producing these lines. 



It is perhaps to the similar high complexity of the gas obtained 

 from cleveite that the curious behaviour of a tube which Professor 

 Ramsay was so good as to send me, must be ascribed. When I 

 received it from him, the glorious yellow effulgence of the capillary, 

 while the current was passing, was a sight to see. But after this 

 had gone on for some time, while the coincidence of the yellow line 

 with D 3 of the chromosphere was being inquired into, the luminosity 

 of the tube was considerably reduced, and the colours in the capillary 



