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Chlorophyl and Eosin Orthochromatic Plates.— In a communication to the Franklin Institute, which we take from the Brit. Jour. of Photography, Mr. Fred. E. Ives, of Philadelphia, Pa., relates some interesting experiments recently made on the combination of chlorophyl and eosin, as follows: The subject of color sensitive photographic processes has received a great deal of attention during the past year or two, but there has been, and is still, a great diversity of opinion in regard to the capabilities of the various color sensitizers. In illustration of this fact I will mention that Becquerel; who first tried chlorophyl, stated that with it he made plates from one-fifth to one-tenth as sensitive to the red of the spectrum as to the blue or violet. Dr. Vogel estimated that eosin-stained plates were eight times more sensitive to the yellow-green of the spectrum than to the blue. I myself stated that plates stained with myrtle-chlorophyl, according to my published method, required even less exposure through a yellow glass than eosin plates. Captain Abney stated that, according to his experience, stained plates were always many times more sensitive to blue and violet than to any other color; and many persons have believed that the color sensitizers acted more by reducing the blue and violet sensiti veness than by actually increasing the sensitiveness to other colors. For the purpose of proving the capabilities of chlorophyl and eosin, I have made four photographs of the lime light spectrum, one on a plain emulsion plate, one on a chlorophyl-stained plate, one on an eosin-stained plate, and one on a plate stained with both chlorophyl and eosin. The spectrum was projected by means of an optical lantern and a flint glass prism, with a slit measuring one-fiftieth of an inch. It will be understood that the different colors have not exactly the same relative intensity in this spectrum that they have in the solar spectrum, but the difference is insignificant. Short wires were placed so as to cast shadows on the sensitive plate, to aid in the comparison of results. Some of these wires, which I have marked, occupy the position of Fraunhofer lines in the solar spectrum. All plates were prepared with the same collodio-bromide emulsion, and received the same exposure and development. The plain emulsion plate shows very little action, except in the blue, violet, and ultra-violet; the maximum of sensitiveness is in the middle of the violet. (It should be noted here that with gelatino-bromide dry plates the maximum
