nable in ordinary fire. Combustible bodies were burnt, and
refractory ones were raised to a white heat, by the concentrated
invisible rays. Thus, by exalting their refrangibility, the invisible
rays of the electric light were rendered visible, and all the colours
of the solar spectrum were extracted from utter darkness. The extreme
richness of the electric light in invisible rays of low refrangibility
was demonstrated, one-eighth only of its radiation consisting of
luminous rays. The deadness of the optic nerve to those invisible
rays was proved, and experiments were then added to show that the
bright and the dark rays of a solid body, raised gradually to
incandescence, are strengthened together; intense dark heat being an
invariable accompaniment of intense white heat. A sun could not be
formed, or a meteorite rendered luminous, on any other condition. The
light-giving rays constituting only a small fraction of the total
radiation, their unspeakable importance to us is due to the fact, that
their periods are attuned to the special requirements of the eye.

Among the vapours of volatile liquids vast differences were also found
to exist, as regards their powers of absorption. We followed various
molecules from a state of liquid to a state of gas, and found, in both
states of aggregation, the power of the individual molecules equally
asserted. The position of a vapour as an absorber of radiant heat was
shown to be determined by that of the liquid from which it is derived.
Reversing our conceptions, and regarding the molecules of gases and
vapours not as the recipients but as the originators of wave-motion;
not as absorbers but as radiators; it was proved that the powers of
absorption and radiation went hand in hand, the self-same chemical act
which rendered a body competent to intercept the waves of aether,
rendering it competent, in the same degree, to generate them. Perfumes
were next subjected to examination, and, notwithstanding their
extraordinary tenuity, they were found vastly superior, in point of
absorptive power, to the body of the air in which they were diffused.
We were led thus slowly up to the examination of the most widely
diffused and most important of all vapours--the aqueous vapour of our
atmosphere, and we found in it a potent absorber of the purely
calorific rays. The power of this substance to influence climate, and
its general influence on the temperature of the earth, were then
briefly dwel