1895.] On the new Gas obtained from Uraninite. 193 



II. " On the New Gas obtained from Uraninite. Fifth Note." 

 By ,T. NOHMAN LOCKYER, C.B., F.R.S. Received May 29, 

 1895. 



In a former communication I pointed out the spectroscope 

 evidence, furnished by the isolation of lines in certain minerals, 

 which indicates that the complete spectrum obtained when brog- 

 gerite is submitted to the distillation method is produced by a 

 mixture of gases. 



In order to test this view, I have recently made some observations, 

 based on the following considerations. 



(1.) In a simple gas like hydrogen, when the tension of the electric 

 current given by an induction coil is increased, by inserting first a 

 jar, and then an air- break into the circuit, the effect is to increase the 

 brilliancy and the breadth of all the lines, the brilliancy and breadth 

 being greatest when the longest air-break is used. 



(2.) Contrariwise, when we are dealing with a known compound 

 gas ; at the lowest tension we may get the complete spectrum of the 

 compound without any trace of its constituents, and we may then, 

 by increasing the tension, gradually bring in the lines of the con- 

 stituents, until, when complete dissociation is finally reached, the 

 spectrum of the compound itself disappears. 



Working on these lines, the spectrum of the spark at atmospheric 

 pressure, passing through the gas, or gases, distilled from broggerite, 

 has been studied with reference to the special lines C (hydrogen), 

 D 3 , 667, and 447. 



The first result is that all the lines do not vary equally, as they 

 should do if we were dealing with a simple gas. 



The second result is that at the lowest tension 667 is relatively 

 more brilliant than the other lines ; on increasing the tension, C and 

 D 3 considerably increase their brilliancy, 667 relatively and absolutely 

 becoming more feeble, while 447, seen easily as a narrow line at low 

 tension, is almost broadened out into invisibility as the tension is 

 increased in some of the tubes, or is greatly brightened as well as 

 broadened in others (fig. 1). 



FIG. 1. Diagram showing changes in intensities of lines brought about by varying 

 the tension of the spark. 1. Without air-break. 2. With air-break. 



p 2 



