7. Zinc and, 8, cadmium distilled over in tlie current of gas.
9. A mixture of boron oxide and magnesium dust, giving elemental 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 pi’oved 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 phosphorus was formed, but no alteration of volume was noticed.
17. The same process ivas 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 pliosphoi’us ; 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 oxide, took place. The mixture was allowed to cool slowly in the current, and the helium was removed with the pump till a phosphorescent vacuum was produced in a vacuum tube communicating with the circuit. The mixture was re-heated, and no helium was evolved—not even enough to show a spectrum. The vacuum remained unimpaired.
It had been hoped that elements with high atomic weight, such as thallium, lead, bismuth, thorium, and uranium might have effected combination, 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. No 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 the 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.
