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.
This article was originally published with the title "Daguerreotypes without Mercury"