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paper, two holes are pierced in it, corresponding to the
images of the two coal points : but falling on a thin plate
of carbon in vacuo, or upon a thin sheet of platinized plat-
inum, either in vacuo or in air, radiant heat is converted
into light, and the image stamps itself in vivid incandes-
cence upon both the carbon and the metal. Results similar to
those obtained with the electric light have also been obtained
With the invisible rays of the lime-light and of the sun.

Before a Cambridge audience it is hardly necessary to
refer to the excellent researches of Professor Stokes at
the opposite end of the spectrum. The above results con-
stitute a kind of complement to his discoveries. Professor
Stokes named the phenomena which he has discovered and
investigated Fluorescence ,' for the new phenomena here
described I have proposed the term Ualoreseenee. He, by
the interposition of a proper medium, so lowered the re-
frangibility of the ultra-violet rays of the spectrum as to
render them visible ; and here, by the interposition of the
platinum-foil, the refrangibility of the ultra-red rays is so
exalted as to render them visible. Looking through a
prism at the incandescent image of the carbon points, the
light of the image is decomposed, and a complete spectrum
obtained. The invisible rays of the electric light, remoulded
by the atoms of the platinum, shine thus visibly forth; ultra-
red rays being converted into red, orange, yellow, green,
blue, indigo, and ultra-violet ones. Could we, moreover,
raise the original source of rays to a sufficiently high tem-
perature, we might not only obtain from the dark rays of
such a source a single incandescent image, but from the
dark rays of this image we might obtain a second one, from
the dark rays of the second a third, and so on—-—a series of
complete images and spectra being thus extracted from the
invisible emission of the primitive source.1

1 On investigating the calorescence produced by rays transmitted
through glasses of various colors, it was found that in the case of certain

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