260 Scientific Intelligence. 
nish ore [pitchblende], oxide of uranium alone is sufficient to 
retain it; but that its presence is not absolutely necessary is 
shown by its existence in monazite and xenotime. The high 
atomic weights of uranium and thorium and the low atomic 
weight of helium suggest some connection; and yet yttrium, 
which possesses a medium atomic weight, sometimes appears to 
favor the presence of the gas; for yttrium is present in yttrotan- 
talite, which, however, contains uranium, and in cleveite, in 
which uranium is present in relatively large amount. 
Of the minerals experimented upon, the only ones which may 
be taken as a source of helium are cleveite, the uraninite investi- 
gated by Hillebrand (Glastonbury, Conn.) and broggerite. Samars- 
kite and yttrotantalite might be added to these, but large quanti- 
ties of these species would have to be worked up. 
In order to fix the density of helium a number of separate 
determinations were made upon the gas liberated from bréggerite 
and cleveite. The final results are as follows: 
Gas from bréggerite by heating.-..---.---- ‘2Abe 
Gas from broggerite with HKSO, ---------- 2°187 
Gas‘from ‘cleveite "2-222 2 22322 eee 2°205 
Mean’ density 233) 22.) a 218i 
The ratio of the two specific heats was also determined by the 
method depending upon the velocity of sound in the gas and the 
value obtained was: 
1°652 
This is very near the theoretical value 1:66. The purest sample 
of argon gave 1°659. It follows that helium has ‘‘the same claim 
to be considered a monatomic gas as mercury gas; or if it is a 
mixture, it must be a mixture of monatomic gases.” 
The solubility of helium was determined by the same method 
employed for argon and the result obtained is 
1 vol. water absorbs 0:0073 volume helium. 
This is the lowest solubility hitherto recorded. The authors, not- 
ing the fact that the solubility of a gas is in general related to 
the temperature at which it condenses to a liquid, remark that 
the low solubility of helium points to a very low boiling point, as 
low or perhaps lower than that of hydrogen. Experiments on 
the temperature of liquefaction are promised by Prof. Olszewski. 
It is added that helium is totally insoluble in absolute alcohol 
and benzene. 
The following remarks upon thespectrum of helium, and finally 
the conclusions to which the work as thus far carried out have led, 
are here quoted in full :— 
The Spectrum of Helium.—Mr. Crookes is making an exhaus- 
tive study of the spectrum of helium, and will shortly publish an 
account of his work. But, as some of the deductions to be 
drawn later depend on the lines observed, it is necessary here to 
