A Manual Of Photography

228 PRACTICE or photography. Gustave Le Gray gives us the following directions and parti- cular information:— First operation.—Dissolve three hundred grains of isinglass in one pint and three quarters of distilled water (for this purpose use a water hath). Take one half of this preparation while warm, and add to it as under:— Iodide of Potassium ........................200 grains. Bromide of ditto ............................60 „ Chloride of Sodium ..........................34 „ Let these salts be well dissolved, then filter the solution througli a piece of linen, put it, still warm, in a large dish, and plunge in your paper completely, leaf by leaf, one on the other, taking care to prevent the air-bubbles from adhering to the paper. Put about twenty leaves at a time into the dish, then turn the whole, those at the top to the bottom, then take them out one by one, and hang them by one corner with a pin bent like the letter 8, to dry spontaneously. When hung up, attach to the opposite corner a piece of bibulous paper, which will facilitate the drying. When the paper is dry cut it the size required, and preserve it in a folio for use ; this paper may be made in the day-time, as it is not sensitive to light in this state. Tlie bromide does not, in this case, act as an accelerator, as it does on the silver plates of the Daguerreotype, because, instead of quickening, it retards the operation a little ; its action is to preserve from the gallic acid the white of the paper, which would blacken more rapidly if you employed the iodide of potassium alone. Second operation.—Prepare, by the light of a taper, the fol- lowing solution in a stoppered bottle : distilled water, 6 fluid ounces, crystallized nitrate of silver, 250 grains. When the nitrate is dissolved, add 1 ounce of crystallizable acetic acid: be careful to exclude this bottle from the light, by covering it with black paper. This solution will keep good until the whole is used. When you wish to operate, pour the solution upon a porcelain or glass slab, surrounded with a glass or paper border to keep the liquid from running off. 1 usually take the solution out of the bottle by means of a pipette, so as to prevent the distribution of any pellicle of dust or other impurity over the glass slab. Take a sheet of the iodized paper by two of the corners, holding them perpendicularly, and gently lower the middle of the paper upon the centre of the slab ; gradually depress until