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THE PHOTOGRAPHIC NEWS. Vol. XII. No. 501.—April 9,1868. CONTENTS. PAGE Sulphur Compounds in Mounting-Boards 169 Photography and Disease - 170 Loss of Sensitiveness in Dry Plates 170 Egg-Albumen, from a Chemical Point of View. By John Spiller, F.C.S 170 The New Photometer. By Dr. Vogel 171 Pictorial Effect in Photography. By II. P. Robinson 173 Adhesive Mediums: A Word or Two in Favour of Paste. By a Practical Man 174 Out-door Photography. By J. R. Heaton 175 PAGE On the Cause of Deterioration of Prints Mounted on Cardboard with Gilt Borders. By MM. Davanne and Fordos 176 Carbon Printing. Bv M. Carey Lea 176 Theoretical and Practical Photography. By Homer Fellows ... 177 Proceedings of Societies—French Photographic Society—North London Photographic Association 178 Correspondence—Photography and Archaeology—Keeping Pro perties of Tannin Plates—Cleaning Varnished Plates 178 Talk in the Studio 179 To Correspondents 180 Photographs Registered 180 SULPHUR COMPOUNDS IN MOUNTING-BOARDS. The presence of hyposulphite of soda in the cards used for mounting photographs has been repeatedly noticed as a source of fading ; but the extent of the mischief arising from this source, it is to be feared, is not realized by photo graphers generally. The number of instances which have recently come under our attention in which disastrous dis colouration and fading in prints was directly traceable to this cause induces us to offer a few further remarks on the subject, with a view to urge upon our readers a more careful examination of the cards upon which valuable photographs are mounted. Mr. England recently called our attention to a curious and annoying illustration of the inj urious influence of the mount ing card. Of a series of his Swiss stereo views, produced and printed some years ago, some were divided and mounted on white cards, the prints being four inches by three ; whilst those intended for stereoscopic slides were mounted in the usual manner on yellow enamelled cards. Having occasion recently to examine some of the small single views which had been packed away, he found, to his surprise and chagrin, that they all showed unmistakeable signs of fading, espe cially noticeable in the yellowness of the whites and lighter tones in the skies. On examination of the stereo slides pro duced at the same time, on the same paper, with the same solutions, from the same negatives, mounted at the same time and in the same manner, and kept in the same place, he found that these were in perfect condition, showing no signs of fading whatever. Every circumstance in relation to the fading and the perfect prints was precisely the same, except the kind of mounting card used. The stereo slides, as we have said, were mounted on the yellow enamelled cards commonly used for that purpose, and the single prints on white cardboard of apparently good quality. On testing the latter, the unquestionable presence of hyposulphite of soda was manifest, although in much less proportion than in many samples we have examined. It is noteworthy that it is in the whites of the picture that the action of sulphur was most decidedly manifest. In some cases the blacks were vigorous, fresh, and perfect in colour, suggesting that the trace of unreduced silver in com bination with the albumen, not removed by the action of the fixing bath, was most readily acted upon by the sulphur compound in the card, whilst the blacks formed by a thicker layer of reduced silver and gold remained un changed. Whore the hyposulphite or other sulphur compound is present in larger quantities, however, all portions of a print readily show its action. We have, on several recent occa sions, had mounted prints sent for examination, in which, within a few weeks after mounting, the whole of the image was changed, the whites having assumed the well known unpleasant yellow tint, and the blacks the greenish brown or olive tint common to the silver print in an advanced stage of sulphurization. In all these cases the plentiful presence of a sulphur compound was readily detected. We use the term sulphur compound in the cards, instead of hyposulphite, as answerable for this disastrous action, because, whilst the evil is most commonly traceable to the latter salt, it is not the only substance used in the manu facture of paper and mounting cards capable of exercising the injurious action to which we refer. In order to secure the pure cold white, or white inclining to blue, of some papers, ultramarine is added to the pulp in the process of manufacture, and as this substance contains sulphide of sodium, its presence is dangerous in a paper or card intended for any photographic use in which it can come into contact with the salts of silver. The simplest test which the photographer can employ to ascertain the fitness of a mounting card for photographic purposes will indicate the presence of either of the sulphur compounds to which we have referred. In the majority of in stances of unsuitable cards which have come under our notice the application of a drop of a 10-grain solution of nitrate of silver is followed immediately by the appearance of a brown stain, which should lead to the unhesitating rejection of the card, In some cases no stain is produced immediately, but if the card be moistened with the silver solution and put away in the dark for a quarter of an hour, after which time the yellow brown stain will indicate the action of sulphur if present. Another mode of using the same test, involving a little more trouble, but more satisfactory when a small portion only of the hyposulphite is present, consists in soaking the suspected card in water for a few hours, and then adding to the water, in a test tube, a few drops of the silver solution, the appearance of the brown discolouration indicating the presence of hyposulphite. The only circum stance which would be likely to render the use of nitrate of silver doubtful in detecting the presence of a sulphur com pound would be the presence of caustic lime, which is, we believe, used at times in manufacturing paper, to give ficti tious substance and weight. This, by producing oxide of silver, would also cause brown discolouration, but the error would be of little importance in a practical sense, since it would only lead to the rejection of a card of very doubtful fitness for mounting photographs. Where the photographer is desirous of employing a more delicate test for the presence of hyposulphite, nothing can be more simple and accurate than iodine for the purpose. Make a solution as follows : iodine one grain, iodide of potassium two grains, dissolved in distilled water one pint. Add a few drops of this, sufficient to give a delicate blue tint to a very dilute solution of arrowroot, and fill two test tubes with the pale blue solution. To one of these add a little of the water in which the suspected card has been