PRESIDENT’S ADDRESS. 31 
its low density and rapid motion, it would soon reach 
the borders of our atmosphere, and leave the earth for 
the sun or some heavenly body of greater mass than the 
earth ; the sun has a mass 300,000 times that of the earth, 
and we know that both hydrogen and helium are abundantly 
present in its chromosphere—the moon is of small mass, 
and is without an atmosphere even of the heavier gases. 
Helium has not yet been liquefied ; its calculated boiling- 
point is below —264° C., or at least 20° lower than that of 
hydrogen, although it is twice the density of hydrogen; 
this is probably accounted for by its molecule being 
monatomic. [Helium has since been liquefied. | 
Professors Ramsay and Collie found that the electric 
spark traverses argon and helium much more readily than 
it does oxygen or hydrogen, and that in fact it is not 
necessary to render a helium tube vacuous in order to 
obtain its spectrum ; the spark passes readily at the ordinary 
atmospheric pressure. 
It is well-known that hydrogen and carbon monoxide 
pass through an iron tube heated to redness. The passage 
of the latter gas through iron stoves is one of the causes of 
the deleterious effects of closed iron stoves, when used in- 
sufficiently-ventilated rooms. Hydrogen also passes through 
warmed platinum and palladium, but neither argon nor 
helium will do so, even at high temperatures ; this is another 
proof of their inertness, for the hydrogen may pass through 
by the formation of an easily-decomposed compound, or by 
the gas being soluble in the metal. 
Sir J. Norman Lockyer, in the Proceedings of the Royal 
Society for September 10, 1897, suggests the name asterium 
for the gas X detected in the spectra of the hottest stars 
and sun. 
He further states that the lines of helium, asterium, and 
hydrogen are accompanied in the hottest stars by other 
lines, which may represent other new gases of a similar 
nature, or metals at a very high temperature. 
