Miscellaneous recipes:
To Clean Glass Plates. (Mr Mayall.) Shake up together alcohol, 30 parts; strong liquid ammonia, 10; water, 40; and fine tripoli, 30 parts. The plates are to be rubbed hard and evenly with balls of cotton wool dipped in this mixture. Rub again, when dry, with a clean ball of cotton; lastly, dust the back and edges with a clean hog-hair brush.
To Clean off Collodion Pictures. This may be done whether they have been varnished or not, by means of a tuft of cotton wool dipped in wood spirit.
To Colour Photographic Prints. This may be done variously in water and oils. A simple way is to rub in slowly with a small camel-hair brush a minute piece of dry colour laid upon the part, as of flesh tint for the face, &c. When properly distributed, the paper may be breathed upon, and the tint will not easily be rubbed off. Or it may be carefully coated with gelatin.
M. Minotto has described a plan of colouring on the back of the paper. The picture, being held up to the light, is first faintly outlined, on the reverse side; colours are then laid on, of water or oil, as preferred, on this side. When dry the paper is rendered transparent by a varnish, and the colours will then appear through it with all the delicacy and effect of a miniature on ivory. Good strong writing paper is best for this purpose; the colours must be vivid; and the varnish may consist of Canada balsam dissolved in turpentine, or a mastic varnish may be used, or turpentine and wax, or oil.
To Remove Stains from the Hands. The powerfully poisonous character of cyanide of potassium renders its employment for the above purpose an operation attended with considerable danger. Iodide of potassium and iodine may both be substituted, but the first is expensive, and the second requires considerable nicety in its application, lest a coloured stain be left on the skin. Instead of the above substances, M. Fortin recommends to wash the hands with a concentrated solution of either sulphate or chloride of zinc, to which some acid is added at the same time. He advises the deepest and blackest stains being touched with metallic zinc, whereby the reduction of the oxide of silver or that of the gallate of iron is promoted, and all metallic stains adhering to or penetrating into the skin removed. Since most of the salts of zinc are colourless, and soluble in water, the hands soon become quite clean. They should then be washed, first with pure water, and next with soap and water.
The reader desirous of further information
on the subject of photography cannot do better than consult Mr Ernest Spon’s valuable manual, entitled ‘Workshop Receipts,’ and Mr Hughes’ ‘Principles and Practice of Photography,’ to both of which we are largely indebted. Captain Abney’s work on ‘Photography,’ cannot be too highly commended. See Collodion, Photographic.
Photographic Waste Products, Recovery of. We extract the following from the ‘American Chemist’ for February, 1876. The contributor, Mr. C. A. Pitkin, A. B., states that the methods given have been collected from the ‘Philadelphia Photographer,’ the ‘British Photographic Journal,’ Hardwick’s ‘Photograph Chemistry,’ &c., &c.; also that they include suggestions by Professor Hill.
1. Nitrate bath, α, recovered; β, renovated.