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and permitting the calorific rays beyond the red to pass
freely through it. This substance was then employed to
filter the beams of the electric light, and to form foci of
invisible rays so intense as to produce almost allthe effects
obtainable in an ordinary fire. Combustible bodies were
burnt and refractory ones were raised to a White heat by the '
concentrated invisible rays. Thus, by exalting their re-
frangibility, the invisible rays of ’ the electric light were
rendered visible, and all the colors of the solar spectrum
were extracted from utter darkness. The extreme richness
of the electric light in invisibleirays of low refrangibility
was demonstrated, one-ninth only of its radiation consisting
of luminous rays. The deadness of theoptic 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 intense incandescence, are
strengthened together; intense dark heat being an inva-
riable 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 im-
portance to us is due' to the fact that their periods are
attuned to the special requirements of the eye.

Among the vapors of volatile liquids vast differences
were also found to exist, as regards their powers of absorp-
tion. We followedvarious molecules frém 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 vapor 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 vapors 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

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