to the Royal Society by Professor Ramsay. Most of these
results are of a technical character, hardly appealing to the average
reader. There is one very salient point, however, in regard to which all
the new substances, including argon and helium, agree; and it is that
each of them seems to be, so far as present experiments go, absolutely
devoid of that fundamental chemical property, the power to combine with
other elements. All of them are believed to be monatomic--that is
to say, each of their molecules is composed of a single atom. This,
however, is not an absolutely novel feature as compared with other
terrestrial elements, for the same thing is true, for example, of such a
familiar substance as mercury. But the incapacity to enter into chemical
combinations seems very paradoxical; indeed it is almost like saying
that these are chemical elements which lack the most fundamental of
chemical properties.

It is this lack of combining power, of course, that explains the
non-discovery of these elements during all these years, for the
usual way of testing an element is to bring it in contact with other
substances under conditions that permit its atoms to combine with
other atoms to the formation of new substances. But in the case of new
elements such experiments as this have not proved possible under any
conditions as yet attained, and reliance must be had upon other physical
tests--such as variation of the bulk of the gas under pressure, and
under varying temperatures, and a study of the critical temperatures
and pressures under which each gas becomes a liquid. The chief reliance,
however, is the spectroscope--the instrument which revealed the presence
of helium in the sun and the stars more than a quarter of a century
before Professor Ramsay ferreted it out as a terrestrial element.
Each whiff of colorless gas in its test-tube interferes with the light
passing through it in such a way that when viewed through a prism it
gives a spectrum of altogether unique lines, which stamp it as krypton,
neon, or zenon as definitely as certain familiar and more tangible
properties stamp the liquid which imprisons it as mercury.

QUERIES SUGGESTED BY THE NEW GASES

Suppose that a few years ago you had asked some chemist, "What are the
constituents of the atmosphere?" He would have responded, with entire
confidence, "Oxygen and nitrogen chiefly, with a certain amount of
water-vapor and of carbonic-acid gas and a trace of ammonia." I