30 PRESIDENT’S ADDRESS. 
Ramsay isolated the gas characterised by the bright 
yellow line; there are also four other brilliant lines, viz., one 
each in the red, green, blue, and violet, but the yellow is 
the most important one. Its density was found to be 
about 2, v.e., twice the density of hydrogen, the lightest 
gas known; in common with argon it is a monatomic gas, 
hence its atomic and molecular weights are identical, viz., 
about 4. 
In his presidential address to the chemical section of the 
British Association at the Toronto meeting, Professor 
Ramsay points out that there should be an element between 
helium and argon with an atomic weight of 20, and if it 
consist of monatomic molecules, hke argon and helium, it 
should have a density of 10; also that like helium and argon 
it should be practically imert and devoid of chemical pro- 
perties. He and his assistant, Dr. Morris Travers, have 
been searching high and low for this element, but up the 
present have not succeeded in finding it. 
In their pursuit after the supposed third gas Ramsay and 
Travers examined a vast number of minerals, and the gases 
given off by sprmgs. They found that most minerals 
evolve gas when heated, consisting for the most part of 
hydrogen, mixed with carbon dioxide, and perhaps traces of 
carbon monoxide, and nitrogen; many gave helium as well, 
although in very small quantities. The helium like the 
nitrogen is probably in combination and not merely occluded 
or imprisoned. 
Argon was only found in the mineral known as malacone, 
and in a specimen of meteoric iron. 
The gas from the mineral springs at Cauterets in the 
Pyrenees was found to be rich in helium, but the unknown 
gas was sought for in vain. The helium found in the gases 
from springs may have been derived from minerals such as 
cleveite and monazite, through which the water has per- 
colated. 
Helium has not been detected in the atmosphere, and it 
is not likely to be found, for like hydrogen on account of 
