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The Paris correspondent of the London Photographic News says:-" Another revolution in photography! The honor of achieving this result is due to Sig. Joseph Eugene Balsamo, Professor of Natural Philosophy at Lucca, in Italy, who has found a substitute for nitrate of silver in positive printing, which is hydrochloric acid saturated with phosphorus, and diluted with acetate of copper. Paper imbued with this compound is exposed to the action of light under a negative, and when it has acquired a gray color, it is removed from the pressure-frame and exposed for five minutes to the vapors of sulphureted hydrogen, which acts upon those parts of the paper which have become altered by the action of light. The picture is afterward toned and fixed in a solution of nitrate of bismuth. A decomposition of the salt of copper takes place, and .the image, which is permanent is formed of oxyd of bismuth. The professor, with that true liberality which characterizes men of science, has given his discovery to the world. His researches in heliography have opened a new path to the photograper, and he promises another communication on this subject ere long.
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