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THE PHOTOGRAPHIC NEWS. Vol. XXVII. No. 1282.—March 30, 1883. CONTENTS. Fading of Photographic Prints 193 A New Method of Photo-Mechanical Printing 193 By-the-Bye.—People who do not Like their Portraits 194 Artificial Light and its Means of Production. By J. Banting Rogers 195 Photo-Lithography, &c. By Major J. Waterhouse, B.S.C 196 Review * 199 Notes 199 Patent Intelligence 201 Twelve Elementary Lessons on Silver Printing 203 PAGE Photographic Experiences in Egypt. By William H. Rau 204 On Pyro Development, By John Carbutt 205 The Pencil and Brush. By The Old Hand 206 Backgrounds for Amateurs: How to Raise a Ghost. By Thomas Gulliver 206 Correspondence 206 Proceedings of Societies 207 Talk in the Studio 207 To Correspondents 208 The Every-Day Formulary 208 FADING OF PHOTOGRAPHIC PRINTS. Very recently we pointed out some remarkable instances of the value of an impermeable support for prints on collodion . chloride, to secure immunity from fading, and we called to { mind that the late Mr. G. W. Simpson, in the directions for ‘ its use, always denounced using an albumen substratum for 1 glass diapositives produced by the process, on account of its liability to initiate the evil. For our own part, we ( have not found this substratum to act in this way, , though that it does initiate fading we are bound to believe on the evidence of others. It may be assumed, we think, that when pure nitrate and chloride of silver are present, without any admixture of albuminate of silver, the fading of a print is unlikely to occur, whilst its presence aids in producing the defect. The use of a collodion emul sion as in the collodio-chloride process is almost pro hibitory for large work on paper, on account of the expense, and also in a minor degree on account of the difficulty experienced in getting an even film. If it be employed, there is no better medium than the enamelled paper to which we alluded in our last, a similar one to which Obernetter employed, and we believe still employs for the purpose. The drawback to the paper is that it will not keep indefinitely, or, indeed, for any longer period beyond a few weeks; the film becomes yellow, and the fixing bath will not always dissolve out the organic silver compound which causes the discolouration. If the emulsion be prepared with an excess of an alka line citrate, the paper retains its colour for a much longer period; but then, as we have already pointed out, the image is wanting in vigour, and is slow in printing. The reason of this is evident: the liberated chlorine from the chloride will with difficulty combine with the citrate, and hence the printing has to take place in an atmosphere, as it were, of free chlorine. If such a paper, however, be prepared with a chlorine absorber, such as tannin, we have the same vigour as is obtained by the excess of free nitrate ; and it should be recollected that free nitrate is only of use where the paper is not totally desiccated. Our readers may remember that, some years ago, we showed at the Photo graphic Society some transparencies on collodio-chloride, and described the manner in which they were produced, insisting on the fuming of the plates with ammonia. The reason of this was obvious, since the plates, which con tained all the soluble salts formed by the double decom position necessary to form the chloride of silver, together with the citric acid and free nitrate of silver, had to be heated before a fire to dry, to prevent sensible crystalliza tion of these salts. All moisture was expelled, aud conse quently the silver nitrate had not the same sensitizing action as when in the ordinary slightly moist condition. The use of ammonia at once gave the necessary chlorine absorbent. In very dry climates, as in America, the fuming with ammonia has to be resorted to, in order to give vigour to an ordinary albumenized print. The question arises as to whether we can prepare a paper with citrate of silver and chloride without collodion, which shall give the necessary degree of permanence. In the list of papers read before the Photographic Society, we have one by Captain Abney, in which he advocates the use of this mixture of sensitive salts in gelatine, and we are in clined to think that in this medium, fading should not take place, since the gelatine is not so ready to combine with silver as it is with citric acid ; and we have a sensitizer ready to hand in the shape of gelatine. On trying the process, we have been well satisfied with the results on the whole, except for a slight degradation of the whites of the print, which must be due either to the colour of the gelatine itself, or else to a combination of the citrate of silver with the gelatine. We are somewhat inclined to the last idea, since if, before fixing such a print, we convert the silver into chloride by immersion in a solution of common salt, this yellowness, to a large extent, disappears, at least so far as our experiments go. We still have the danger, however, of hyposulphite of silver remaining behind after washing, and it may well be that this salt might combine with the gelatine, and eventually give rise to fading. It is, however, our present opinion that this is not nearly so likely to be the case as with albumen, and we may remark parenthetically that the toning of a gelatino-citro chloride print is not more difficult than of a collodio-chloride print, and the same toning baths may be used. Our conclnsion, nevertheless, is that a silver printing process which will give permanence is only to be found when we have a definite crystalline organic silver compound formed, such as the citrate, and not a colloidal compound, snoh as albumenate present; and when the support is such as collodion, where the washing can be thoroughly executed, owing to its porosity, for then all products soluble in water can be eliminated, and we see no reason why a silver print should not be as permanent as its would-be rival in public affection. A NEW METHOD OF PHOTO-MECHANICAL PRINTING. At the last meeting of the Photographic Club, the subject of obtaining photographs by means of a pinhole, instead of a lens, was again brought forward ; and it was pretty generally admitted that one principal source of difficulty is the drilling of a clean hole in an extremely thin sheet of metal; while a punched hole is almost invariably tubular or funnel-shaped, owing to the obtrusion of the metal round about the true image forming aperture. In such a case, or if the opaque screen in which the hole is drilled is not extremely thin, the reflection of light from the aides