154 Moss—On the State in which Helium Evists in Pitehblende. 
Having completely exhausted the apparatus, the gas was removed, and found 
to measure 0-092 cubic centimetre at 0°C. and 760 mm. pressure. The phosphorus 
pentoxide tube was found to have gained in weight 0:0199 gramme. This weight 
of water corresponds to about 24 ¢.c. of water vapour at 0°C. and 760 mm. 
pressure; water is, therefore, the chief substance liberated in the pulverisation 
of the pitchblende. 
The gas was examined by exposing it to the action of potassium hydroxide, 
and then heating a fragment of dry phosphorus init. The results obtained were 
as follows, the volumes being calculated for 0°C. and 760 mm. pressure :— 
Original volume of gas, es oe 0:092 
After action of KHO, af ye 0-078 
95 sf OI “dg ae 0-076 
From these results the composition of gas, assuming only carbon dioxide and 
oxygen to be removed by the alkali and phosphorus, is— 
Per Cent. 
CO,, “i .. 0014 15-41 
O, ae ae 0-002 2°33 
Other gases, LS ace 0-076 82°26 
0-092 100-00 
The quantity of gas available was too small for detailed examination; accord- 
ingly I introduced it into a thoroughly exhausted Pliicker tube with magnesium 
terminals. The volume to which the gas was expanded in this operation was 
approximately 22 cubic centimetres; its pressure would, therefore, be 2°6 mm. 
On passing the current from a small induction coil, giving a spark of about 7 
centimetres, I obtained a discharge which gaye only the nitrogen spectrum. On 
introducing a jar and spark-gap, a deposit of magnesium was rapidly formed on 
the sides of the Pliicker tube, and the nitrogen spectrum faded rapidly, and in a 
few seconds was succeeded by an almost pure helium spectrum. 
In this experiment the pitchblende had been ground to a rather coarse powder ; 
there were many fragments fully a millimetre in diameter. This powder was 
again placed in the mill, and the operations above described were repeated. The 
volume of gas now obtained was 0:0941 c.c. This gas was treated as in the 
former experiment, but the attempt to determine the quantity of oxygen was not 
successful ; a very slight increase in volume instead of a diminution was caused 
by the) action of hot phosphorus. The gas was, however, introduced into the 
Pliicker tube with magnesium terminals. The spectra of nitrogen and helium 
were both visible, but almost immediately the nitrogen spectrum disappeared. 
