A Manual Of Photography

MR. CUNDELh’s PROCESS. 223 effect in twelve or twenty-four hours, according to the thickness of the paper. It is essential to the success of the fixing processs that the paper he in the first place thoroughly penetrated by the hyposulphite, and the sensitive matter dissolved; and next, that the hyposulphite compounds he effectually removed. Unless these salts are completely removed, they induce a destructive change upon the picture; they become opaque in the tissue of the paper, and entirely unfit it for the next, which is 15. The Printing Process.—The picture being thus fixed, it has merely to he dried and smoothed, when it will undergo no further change. It is, however, a negative picture, and it it have cost some trouble to produce it, that trouble ought not to be grudged, considering that you are now possessed of a matrix which is capable of yielding a vast number of beautiful im- pressions. 1 have had as many as fifty printed from one, and 1 have no doubt that as many more might he obtained from it. 16. The manner of obtaining these impressions have been so often described, and there are so many different modes of proceeding, that it may be sufficient to notice very briefly the best process with which I am acquainted. Photography is indebted for it to Dr. Alfred Taylor. His solution is made by dissolving one part of nitrate of silver in twelve of distilled water, and gradually adding strong liquid ammonia until the precipitate at first produced is at length just redissolved. 17. Some paper is to he met with, containing traces of bleach- ing chlorides, which does not require any previous preparation; but in general it will be found necessary to prepare the paper bv slightly impregnating it with a minute quantity of common salt. This may he done by dipping it in a solution in which the salt can barely be tasted, or of the strengtli of from thirty to forty grains to a pint of water. The paper, after being pressed in clean blotting-paper, has merely to be dried and smoothed, when it will be fit for use. 18 The ammonio-nitrate of silver is applied to the paper in the manner described in § 3; and, when perfectly dry, the negative picture to be copied is to he applied to it, with its face in contact with the sensitive side. The hack of the negative picture being uppermost, they are to be pressed into close contact bv means of a plate of glass ; and, thus secured, they are to he exposed to the light of the sun and sky. The exposed parts of the sensitive paper will speedily change to lilac, slate- blue deepening towards black ; and the light, gradually penetrating through the semi-transparent negative picture, will imprint upon the sensitive paper beneath a positive impression. The negative picture, or matrix, being slightly tacked to the