Daguerreotypes without Mercury

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M. Natterer, of Vienna, has discovered a process for obtaining proofs on iodized plates wifh the chloride of sulphur, without the use of mercury. A plate of silver is iodized in the usual manner, and then placed on the top of a vessel 6 or 8 inches high, having at the bottom, in a small cup, a few drops of chloride of sulphur; it should remain exposed to the action ol the vapor until the sombre yellow color is changed to a red, after which it is brought to a focus in the camera, where it is left for a time, depending upon the luminous strength of the focus of the objective. (With the objectives of Petzval-Voigtlander, not less than ten seconds and not more than two minutes,) The plate is then taken out and examined in the camera by the light of a candle. It often orcurs that no trace ol the image is as yet perceptible, but if the plate is heated by placing over a spirit lamp the j, unprepared side, or if left for some time in the dark, or, lastly, if exposed only for a few seconds to a weak dimmed light, the positive picture then appears with all its shades. Of these three modes of bringing out the image, the second is superior to the others.

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