"Placing the paper on some hard body, wash it over on one side--by means of a very soft camel's hair pencil--with a solution of sixty grains of bromide of potassium, in two fluid ounces of distilled water, and then dry it quickly by the fire. Being dry, it is again washed over with the same solution, and dried as before. A solution of nitrate of silver--one hundred grains to an ounce of distilled water--is to be applied over the same surface, and the paper quickly dried in the dark. In this state the papers may be kept for use. "When they are required, the above solution of silver is to be plentifully applied, and the paper placed wet in the camera, the greatest care being taken that no day light--not even the faintest gleam--falls upon it until the moment when you are prepared, by removing the dark slide, to permit the light, radiating from the object you wish to copy, to act in producing the picture. After a few seconds the light must be again shut off, and the camera removed into a dark room." The necessity of removing the camera is now avoided by the use of the dark slide, already described, covering the picture in the holder, which alone may be removed.--Amer. Aut. "It will be found by taking the paper from the holder, that there is but a very faint outline--if any--yet visible. Place it aside, in perfect darkness until quite dry; then place it in the mercurial vapor box (meaning bath) and apply a very gentle heat to the bottom. The moment the mercury vaporizes, the picture will begin to develope itself. The spirit lamp must now be removed for a short time, and when the action of the mercury appears to cease, it is to be very carefully applied again, until a well defined picture is visible. The vaporization must then be suddenly stopped, and the photograph removed from the box. The drawing will then be very beautiful and distinct; but much detail is still clouded, for the developement of which it is only necessary to place it in the dark and suffer it to remain undisturbed for some hours. There is now an inexpressible charm about the pictures, equaling the delicate beauty of the daguerreotype; but being very susceptible of change, it must be viewed by the light of a taper only. The nitrate of silver must now be removed from the paper, by well washing it in soft water, to which a small quantity of salt has been added, and it should afterwards be soaked in water only. When the picture has been dried, wash it quickly over with a soft brush dipped in a warm solution of hyposulphite of soda, and then wash it for some time in distilled water, in order that all the hyposulphite may be removed. The drawing is now fixed and we may use it to procure positive copies, (the original being termed a negative,) many of which may be taken from one original."