"Yours respectfully,
"M. A. ROOT."
In our second edition, we hope--with Mr. Root's permission--to lay the whole process before the public, although our artists must bear in mind that Mr. Root's patent secures to him the exclusive right of its application.
CHAP. XI.
ON THE PROBABILITY OF PRODUCING COLORED PICTURES BY THE SOLAR RADIATIONS--PHOTOGRAPHIC DEVIATIONS--LUNAR PICTURES--DRUMMOND LIGHT.
Having before noticed the fact that some advances had been made towards taking 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."