Helium and Argon, their Inactivity. 55 



7. Zinc and, 8, cadmium distilled over in the current of gas. 



9. A mixture of boron oxide and magnesium dust, giving ele- 

 mental boron, produced no absorption. 



10. Similarly, a mixture of yttrium oxide and magnesium dust 

 had no effect. 



11. Thallium was heated to bright redness in the gas, retaining 

 its metallic lustre. 



12. Titanium oxide mixed with magnesium dust was heated to 

 bright redness, and caused no absorption. 



13. Similar absence of action was proved with thorium oxide and 

 magnesium powder. 



14. Tin and, 15, lead, were heated to bright redness in the current 

 of gas, and remained untarnished. 



16. Phosphorus was distilled in the gas, and caused to pass through 

 a length of combustion-tube heated to softening. Some red phos- 

 phorus was formed, but no alteration of volume was noticed. 



17. The same process was repeated with elemental arsenic. 



18. Antimony and, 19, bismuth, at a bright red heat, retained their 

 metallic lustre. 



20. Sulphur and, 21, selenium, were treated in the same way as 

 phosphorus ; no action took place. 



22. Uranium oxide, mixed with magnesium dust, was heated to 

 bright redness in helium. No change, except the reduction of the 

 >xide, took place. The mixture was allowed to cool slowly in the 



irrent, and the helium was removed with the pump till a phos- 

 )horescent vacuum was produced in a vacuum tube communicating 

 rith the circuit. The mixture was re-heated, and no helium was 

 rolved not even enough to show a spectrum. The vacuum remained 

 [impaired. 



It had been hoped that elements with high atomic weight, such as 

 thallium, lead, bismuth, thorium, and uranium might have effected 

 )mbination, but the hope was vain. 



23. A mixture of helium with its own volume of chlorine was 

 exposed to a silent discharge for several hours. The chlorine was 

 contained in a reservoir, sealed on to the little apparatus which had 

 the form of an ozone apparatus. ISTo change in level of the sulphuric 

 acid confining the chlorine was detected after the temperature, raised 

 by the discharge, had again become the same as that of tlie room. 

 Hence helium and chlorine do not combine. 



24. Metallic cobalt in powder does not absorb helium at a red heat. 



25. Platinum black does not occlude it. 



26. It is not caused to combine by passage over a mixture of 

 soda- lime and potassium nitrate heated to bright redness. This was 

 hardly to be expected, for it resists the action of oxygen in presence 

 of caustic soda, even when heated by the sparks which traverse it. 



