ng Daguerreotypes in color, by means of solar rays, and expressed
the hope that the day was not far distant when this might be
accomplished, I here subjoin Mr. Hunt's remarks on this subject.

Mr. Biot, in 1840, speaking of Mr. Fox Talbot's beautiful calotype
pictures, considers as an illusion "the hope to reconcile, not only the
intensity but the tints of the chemical impressions produced by
radiations, with the colors of the object from which these radiations
emanated." It is true that three years have passed away, and we have
not yet produced colored images; yet I am not inclined to consider the
hope as entirely illusive.

It must be remembered that the color of bodies depends entirely upon
the arrangement of their molecules. We have numerous very beautiful
experiments in proof of this. The bi-niodide of mercury is a fine
scarlet when precipitated. If this precipitate is heated between
plates of glass, it is converted into crystals of a fine sulphur
yellow, which remain of that color if undisturbed, but which becomes
very speedily scarlet if touched with any pointed instrument. This
very curious optical phenomena has been investigated by Mr. Talbot and
by Mr. Warrington. Perfectly dry sulphate of copper is white; the
slightest moisture turns it blue. Muriate of cobalt is of a pale pink
color; a very slight heat, by removing a little moisture, changes it to
a green. These are a few instances selected from many which might be
given.

If we receive a prismatic spectrum on some papers, we have evidence
that the molecular or chemical disturbance bears some relation to the
color of each ray, or, in other words, that colored light so modifies
the action of ENERGIA that the impression it makes is in proportion to
the color of the light it accompanies, and hence there results a
molecular arrangement capable of reflecting colors differently. Some
instances have been given in which the rays impressed correspond with
the colors of the luminous rays in a very remarkable manner.* One of
the most decided cases is that of the paper prepared with the fluoride
of soda and nitrate of silver. Sir John Herschel was, however, the
first to obtain any good specimens of photographically impressed
prismatic colorations.

* See Mr. Hunt's "Researches on Light."

It was noticed by Daguerre that a red house gave a reddish image on his
iodized silver plate in the camera obscura; and Mr. Talbot observed,
very early in his researches