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ON THE STATE IN WHICH HELIUM EXISTS IN PITCHBLENDE. 
By RICHARD J. MOSS, E.I.C., F.C.S. 
[Read, Junz 21; Published, Novemprr 3, 1904. | 
ALTHOUGH no compound of helium has been artificially produced, it is possible 
that the element may exist in a chemically combined state in the minerals from 
which it is obtained. The methods employed to liberate helium from these 
minerals are such as may, and in many cases certainly do, give rise to chemical 
decompositions. On the other hand, the fact that helium is derived from the 
emanation from radium affords a strong argument in favour of the supposition that 
the gas exists in some chemically uncombined form in the radio-active minerals. 
With the view of throwing some light upon this point, I carried out the follow- 
ing experiments on a specimen of pitchblende said to be from Joachimsthal, but 
having a specific gravity of only 5°32. It is part of a specimen which has been in 
the Science and Art Museum, Dublin, for about forty years. 
The pitchblende was broken into fragments of about 2 to 3 grammes each, 
and placed in a desiccator over sulphuric acid for several days. 
The fragments, weighing 72°7 grammes, were quickly transferred to the 
hopper of a mill for grinding substances tm vacuo, and which will form the subject 
of a future communication. A bell-glass which covers the mill, having been 
warmed in the water oven, was placed in position, and the Tépler pump with which 
the apparatus was connected was immediately started, and kept in action until 
the limit of exhaustion had been reached. When it was found that working the 
pump for ten minutes failed to remove any trace of gas, the apparatus was allowed 
to stand. The next day, on working the pump, a minute bubble of gas was 
obtained ; it was too small to suggest leakage, and was discarded. The grinding 
of the mineral was now started, and immediately I noticed that the tube con- 
taining phosphorus pentoxide, which formed part of the connection between the 
grinding-mill and the pump, became warm, showing that water was liberated as 
a result of the pulverisation of the mineral. At the same time the pump, which 
was kept going continuously, began to bring over some bubbles of gas. The 
whole operation of grinding the mineral lasted seven minutes. 
TRANS ROY, DUB, SO0., N.S., VOL, VIII., PART XII, 25 
