Iodide of potash 200 grains. Mannite 6 drachms. Cyanide of potash 5 grains. Distilled water 20 ounces. Allow it to remain three hours, taking care that air-particles are perfectly excluded, and once during the time turning over each sheet of paper, as many being inserted as the fluid will conveniently cover, as it is not injured by after keeping. It should be then removed from the iodide bath, pinned up, and dried, ready for use. When required to be excited, the paper should, by the light of a candle, be immersed in the following solution, where it should remain for five minutes: Nitrate of silver 4 drachms. Glacial acetic acid 4 drachms. Distilled water 8 ounces. Being removed from the aceto-nitrate bath, immerse it into a pan of distilled water, where let it remain about a quarter of an hour. In order to make this paper keep a week or two, it must be immersed in a second water, which in point of fact is a mere reduction of the strength of the solutions already used; but for ordinary purposes, and when the paper is to be used within three or four days, one immersion is quite sufficient, especially as it does not reduce its sensitiveness in a needless way. It may now be preserved between blotting-paper, free from light, for future use. The time of exposure requisite for this paper will exceed that of the ordinary unwaxed, given in the previous directions. The picture may be developed by a complete immersion also in a saturated solution of gallic acid; but should it not have been exposed a sufficient time in the camera, a few drops of the aceto-nitrate solution added to the gallic acid greatly accelerates it. An excess of aceto-nitrate often produces an unpleasant red tint, which is to be avoided. Instead of complete immersion, the paper may be laid upon some waste blotting-paper, and the surface only wetted by means of the glass rod or brush. The picture may now be fixed by the use of the hyposulphite of soda, as in the preceding process. It is not actually necessary that this should be a wax-paper process, because ordinary paper treated in this way acts very beautifully, although it does not allow of so long keeping for use after excitement; yet it has then the advantage, that a negative may either be waxed or not, as shall be deemed advisable by its apparent depth of action. HUGH W. DIAMOND. [Footnote 3: the gallic acid was omitted in Issue 166, but inserted by an erratum in Issue 168. Also "a saturated solution of gallic acid" was printed as "a solvent solution ...", "hyposulphate" appeared for "hyposulphite" throughout, and "solari_s_e" for "solari_z_e"--Transcriber.]