1914] 



on Further Researches on Positive Rays 



2C5 



meiit by cathode rays, or that given off when metals are heated to a 

 very high temperature ; these gases are known to contain hydrogen. 

 In order to get the conditions as simple as possible I tried\he 

 bombardment of ice, made from water which had been boiled for a 

 long time so as to expel any gases which might be dissolved in it. 

 This water was placed in a discharge tube which was immersed in 

 liquid air, the vessel pumped by a Gaede pump to take away all the 

 gases which were not condensed by the great cold, and the block of 

 ice bombarded for some hours by cathode rays. The rays bored 

 a large hole in the ice, as you will see when I break this bulb which 

 contains ice which has been bombarded. The gas driven off from the 

 ice by the bombardment contains comparatively large quantities of Xg, 

 the source of the line in question. The bombardment of frozen 



/ 



Fig. 1. 



ammonia NHg is also a source of Xg, and it would seem that it must 

 be derived in some way from the hydrogen in these compounds. 

 The connection of Xg with hydrogen is also indicated by the fact 

 that X3 is found in hydrogen through which an electrodeless dis- 

 charge had been passed for several hours. 



»' ' I have also obtained X3 from gas which had not been subjected 

 to electric currents by greatly heating crystals of phosphorium iodide, 

 PH^I ; the gas obtained in this way showed X3 very distinctly. The 

 photographs obtained with this gas were also interesting, because they 

 showed on the negative side a parabola corresponding to the molecular 

 weight 34, PH3 ; the existence on the negative side of molecules either 

 of elements or compounds is, as I said before, very exceptional. 

 . ■ There is further evidence which, though indirect, seems to me of 

 very considerable strength. The horizontal distance of the head of 

 the parabola from the verticle line OY, passing through the unde- 



