Fixing Solution (for Negatives). Hyposulphite of soda, 5 oz.; distilled water, 5 oz.; dissolve and filter.
Sensitising Solution (for Paper). Nitrate of silver, 5 dr.; distilled water, 5 oz.; nitric acid, 2 drops; kaolin, 1 oz. Dissolve the nitrate of silver in the water, and then add the acid and kaolin; the kaolin will not dissolve, its use being to prevent the solution becoming discoloured after using. This solution will not require filtering; it must be allowed to become quite clear, and when required for use must be carefully decanted. This solution should be occasionally tested with the argentometer, and sufficient nitrate of silver added to restore it to its original strength.
Another Negative Collodion. Ether, 1⁄2 oz.; gun-cotton, 7 gr.; bromide of cadmium, 1⁄2 gr.; bromide of ammonium, 11⁄2 gr.; iodide of calcium, 1 gr.; iodide of potassium, 1 gr.; iodide of ammonium, 1 gr. For intensifying, flood with chloride of gold, 1 gr.; water, 15 oz.; then wash, and flood with pyrogallic acid, 2 gr.; water, 3 oz.
Toning Baths. 1. Chloride of gold, 4 gr.; acetate of soda, 1⁄4 oz.; distilled water, 10 oz.; dissolve and filter. 2. To produce black to bright sepia tones, according to length of immersion. Take carbonate of soda sufficient to cover a threepenny piece, dissolve it in a teaspoonful of cold water in a cup, add 2 gr. of chloride of gold, then add 3 oz. of boiling water; use in 15 minutes. This will suit Hart’s albuminised paper.
Fixing Solution (for Paper Prints). Hyposulphite of soda, 8 oz.; distilled water, 1 pint. This solution must only be used once.
Stopping-out Negatives. Small, round, transparent spots are frequently found on glass negatives, which, if not stopped, occasion corresponding black spots on the print. Lay the plate on a slab of glass, having either direct or reflected light shining up through it. Then cover the spots with a mixture composed of 10 parts of ivory black, 2 parts of saturated solution of gum Arabic, 2 parts of white honey, 1 part of sugar-candy; well mix and apply with a fine camel-hair brush. Should the spots on the negative be black or opaque, white spots will be formed on the print; these are easily tinted with a little water colour, to match the other portions of the print; it is seldom necessary, therefore, to alter the negative on this account.
Ferrotypes. In these, instead of a glass plate being used to receive the picture, as in a positive glass photograph, a thin plate of black varnished iron is employed. Of course no black backing is required; with this exception the photograph is produced in every particular by the same means and in the same manner as the glass positive is.
To Clean Glass Plates. (Mr Hughes.) The description of glass known as “flatted crown” is well suited for positives, but before using it requires careful cleaning. The sharp edges should be first removed with a “corundum” file, or by drawing the sharp edge of one
piece over the sharp edge of another; then place the glass on a clean flat surface, or put it in “a plate-cleaning holder,” and pour a few drops of the plate-cleaning solution in the middle. Rub it carefully over every part with a bit of clean soft rag; turn the glass over, and do the other side the same. Then polish each side with a clean cloth, and finish with a soft chamois leather kept expressly for this purpose. Now breathe on the glass, and if the breath deposits evenly the plate is clean. If the plate, however, shows patches and marks, it must be recleaned. Let the edges be carefully wiped, and the plate is ready for use.
The following preparation makes a good plate-cleaning solution for glasses that require mechanical friction to make them clean:—Ordinary water, 5 oz.; alcohol, 5 oz.; iodide of potassium, 15 gr.; iodine, 3 gr. When dissolved, add tripoli, prepared chalk, whiting, or rotten-stone, in sufficient quantity to make a creamy paste.