392 Profs. Gr. D. Liveinsj and J. Dewar. On the 



about X 5420, 5292, and 4922, and then the krypton rays soon died ou 

 and were superseded by the xenon rays. At this stage the. capillary 

 part of the sparking tube is, with a jar in circuit, a brilliant green 

 and is still green, though less brilliant, without the jar. The xenon 

 formed the final fraction distilled. 



Subsequently an improved form of apparatus was used for the frac- 

 tionation. It is represented in fig. 2. A gasholder containing the 



Fig. 2. 



tnUt;-* 



gases to be separated, that is to say, the least volatile part of atmo- 

 spheric air, was connected with the apparatus by the tube a, furnished 

 with a stopcock c. This tube passed on to the bulb B, which in turn 

 communicated through the tube b and stopcock d with a sparking 

 tube, and so on through the tube e, with a mercurial pump.* Stopcock d 

 being closed and c opened, gas from the holder was allowed to pass 

 into B, maintained at low temperature, and there condensed in the 

 solid form. Stopcock c was then closed and d opened, and gas from B 

 allowed to pass into the exhausted tubes between B and the pump. 

 The tube e was partly immersed in liquid air in order to condense 

 vapour of mercury, which would otherwise pass from the pump into 

 the sparking tube. The gas passing into the sparking tube would, of 

 course, have a pressure corresponding to the temperature of B, and 

 this was further ensured by making the connecting tube pass through 

 the liquid in which B was immersed. The success of the operation of 

 separating all the gases which occur in air and which boil at different 

 * The Sprengel pump shown in figure is simply diagrammatic. 



