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DRY PLATES, FILMS AND PAPERS 195
but before this is done it is usual to alter the appearance of the image by " toning " it in a bath containing gold chloride. When immersed in a suitable bath made up of chloride of gold, distilled water and ammonium sulphocyanide, a quantity of the gold is deposited on the image and the tone or appearance changes.
Many persons now adopt a combined toning and fixing bath, and if proper precautions are taken, very satisfactory results may be obtained by this method. It will be found advisable to immerse the prints in a fixing bath after removal from the combined bath if permanence is desired. After fixing, the prints must be thoroughly washed in running water so as to remove every trace of hypo.
It might be mentioned that the Gold Toning is also arranged for by the tabloid makers, and that such methods are to be recommended to a beginner, as the difficulty of obtaining pure chemicals in absolutely correct quantities has thus been overcome.
Phosphate Paper. — A relatively new form of sensitized paper known as Phosphate Paper can be used either in weak daylight [5 seconds at about 6 feet from a window] or artificial light, and when developed, fixed and washed [but without the action of gold], the results obtained are similar to those with P.O. P.
Metol is recommended as the developer for these papers, and an acid fixing bath composed of hypo, 3 oz. ; metabisulphite of potash, \ oz. ; and water to make up 20 ounces is employed for one minute only.
Bromide and Gaslight Papers. — This Phosphate paper is not so well known as the bromide and gaslight papers, which have been for some time in common use for obtaining positive prints by artificial light. The gaslight are much less sensitive than the bromide papers, and no dark room is required for their development . As their name indicates, bromide papers are made sensitive to the action of light by the presence of a gelatino bromide emulsion similar to