Photography in Colors.

Manufacturer and builder 1, 1891

Captain Abney, a distinguished authority on photography, in a paper on the effect of light on matter, read before the British Association, said:

"The question is often asked when photography in natural colors will be discovered. Photography in natural colors not only has been discovered, but pictures in natural colors have been produced. I am not alluding to the pictures produced by manual work, and which have from time to time been foisted on a credulous public as being produced by the action of light itself, much to the damage of photography, and usually to the socalled inventors. Roughly speaking, the method of producing the spectrum in its natural colors, is to chlorinize a silver plate, expose it to white light till is assumes a violet color, heat till it becomes rather ruddy, and expose it to a bright spectrum. The spectrum colors are then impressed in their natural tints. Experiment has shown that these colors arc due to an oxidized product being formed at the red end of the spectrum and a reduced product at the violet end. Photography in natural colors, however, is only interesting from a scientific point of view, and, so far as I can see, can never have a commercial value.

"A process, to be useful, must be one by which reproductions are strictly made; in other words, it must be a developing and not a printing process, and it must be taken in the camera, for any printing process requires not only a bright light, but also a prolonged exposure. Now, it can be conceived that in a substance which absorbs all the visible spectrum, the molecules can be so shaken and sifted by the different rays, that eventually they sort themselves into masses which reflect the particular rays by which they are shaken; but it is almost — I might say quite — impossible to believe that when this sifting has only been commenced, as it would be in the short exposure to which a camera picture is submitted, the substance deposited to build up the image by purely chemical means would be so obliging as to deposit in that the particular size of particle which should give to the image the color of the nucleus on which it was deposited. I ant aware that in the early days of photography we heard a good deal about curious results that bad been obtained in negatives, where red-brick houses were shown as red anti the blue sky as bluish. The cause of these few coincidences is not hard to explain, and would be exactly the same as when the red- brick houses were shown as bluish and the sky as red in a negative. The records of the production of the latter negatives are naturally not abundant, since they would not attract much attention. I may repeat, then, that photography in natural colors by a printing-out process — by which I mean by the action of light alone — is not only possible, but has been done, but that the production of a negative in natural colors front which prints in natural colors might be produced, appears, in the present state of our knowledge, to be impossible. Supposing it were not impracticable, it would be unsatisfactory, as the light with which the picture was impressed would be very different from that in which it would be viewed.

"Artists are fully aware of this difficulty in painting, and take their precautions against it. The nearest approach to success in producing colored pictures by light alone, is the method of taking three negatives of the same subject through different colored glasses, complementary to the three color sensations which together give to the eye the sensations of white light. The method is open to objection on neeonnt of the impure color of the glasses used. If a device could be adopted whereby only those three parts of the spectrum could be severally used which form the color sensations, the method would be more perfect than it is at present. Even then perfection could not be attained, owing to a defect which is inherent in photography, and which cannot be eliminated. This defect is the imperfect representation of gradation of tone. For instance, if we have a strip graduated from what we call black to white (it must be recollected that no tone can scientifically be called black and none white), and photograph it we shall find that in a print from the negative the darkness which is supposed to represent a gray of equal mixtures of black and white, by no means does so, un less the black is not as black or the white as white as the original."