A Manual Of Photography

134 SCIENTIFIC INVESTIGATIONS ON PHOTOGRAPHY. but this beautiful salt (chromato of silver) has not vet boon applied directly as the photographie agent In titrate of silver, resemble in their character those prepared with the muriates, but are not darkened so ecu. The tartrate of silver possesses some very eà^ 1i■ ; other paper.g This discolouration may be wonderfully every I P* over the tartrated paper with a very Solution of the hydriodate of potash, during the process of darkening It is not easy to use this when copying anything, but there ^ cases in which the extreme degree of darkness which this preparation acquires renders it valuable. Ihe acetate of silver comports itself in the same manner as the tartrate The citrate oxalate, Le., are only interesting as forming part of the series of argentine preparations which exhibit decisive eLtes when exposed to light. The methods of rendering them available will be sufficiently understood from the foregoing details and it would only be an unnecessary waste of words to •more particular directions as it regards them. nFulminate of Silver.—Notwithstanding the extraordinary decree of sensibility which has been given to paper and tee metallic plates by the industrious compounds present a very promising line o f myself Towson, of Devonport, who pursued, coni Y’ aunts’ a most extensive series of researclies on P ’ endeavouring to form a solution of silver, in which the elements should be so delicately balanced as to be overturned