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June 1, 1883.) THE PHOTOGRAPHIC NEWS. 343 quarter of an-hour before the digestion is over, put 30 grains of hard gelatine to it, and then put it in the flat dish. After standing twelve hours to cool, pass it through the canvas into the muslin, which is spread over the flat wash-basin containing water. The squeezing operation should be done under the water. Then take the muslin with the emulsion substance, holding it by the four corners, out of the water (which will contain no particles of emulsion worth saving), and hold it under a water tap for a quarter of an hour, taking care that the water is well spread all over the emulsion ; after hang it up to drain for half an hour, and then put the substance in the marked milk-cup, and add to it stock solation W, until the contents weigh 1,400 grains, as the drained emulsion will only weigh about 900 to 1,000 grains. Now warm it in warm water of 40% for an hour, and keep the water the same ; then filter through fine linen of three thicknesses into another white milk-cup ; in this way you always know the exact strength of the emulsion, and can exactly calculate how much you may spread over a plate. For example, over a half plate, 13 by 18 c., take a pipette holding 7 grm. ; this pipette is also very useful to help in flowing the emulsion all over. To test the emulsion as to its goodness, take a little of it in a testing-glass and put a small quantity of tannic acid solution to it, and if the substance should turn coloured, especially when it becomes a deep red colour, you may be sure that the emulsion is over-boiled, and the plate prepared with such an emulsion will veil. In summer time, or when the weather is warm, keep your liquid emulsion, for spreading over the plates, at a tempe rature not higher than 30° (dissolving degree, 40° C.), because the liquid matter would take too long a time to set, and so the brom-silver particles would fall in the substratum nearest to the plate, and the surface would show a glazed appearance ; in this state, the plates take a much longer time to. develop, and the image would have a flat appearance, and be thin and poor. In the contrary case, it will develop very easily, and in full strength, and the unfixed negative shows on the glass side only very little, whereas the other sort shows the image already when the picture is only half developed; and when fully developed, it is equally distinguishable on either side, and such plates must be treated with the developer a much longer time, to get strength. The cloths dirtied by the emulsion are to be well washed in several different quantities of hot water, and may then be kept in water containing a few drops of carbolic acid. This is much better than drying them after use ; before using them, wash them again. This 1,400 grms. of emulsion is the given quantity for 200 half-plates, or four and a half square metre. For drying the plates, I have had in use for the last two years a drying-cupboard of my own idea, and am so pleased with it that I think it may be useful to others ; the only fault it has, is, it takes up much room. It is a kind of table and drying cupboard : A is a horizontal table ; B is a kind of frame to make a rigid standfor the levelling bars, which carry set screws, on which is placed the plate-glass, F ; G is a lid, that can be lifted up or closed air-tight over the levelling stand, so that the air which comes from the opening below, may pass over the plates, and is obliged to go through the chimney, K ; the open ing must be four or five times as wide as the opening at K, so as to give time for the air to absorb the moisture. To make a current of air, it is useful to put a lamp in the chimney, and at the same time you can turn the light through a window of red glass, to good account. The table is about 4 meters long, one metre wide, and one foot in height. Gelatine dry plates require, in such a cupboard, fifteen to twenty hours to get dry. After this you may stand them upon shelves to allow them to dry also on the other side. The glass which I use for dry plates is washed with water acidulated by nitric acid, and then swilled under a clear water tap ; the finishing is given with distilled water, containing a few drops of carbolic acid. For developing the plates, I always use pyrogallic acid, ammonia, brom-salt, and ordi nary water, and can employ the developer for six to eight plates. It keeps perfectly for three hours by refreshing it with a very little ammonia bromide solution. For washing the negatives, I may strongly recommend running water, instead of washing in dishes. For varnishing, I can give you a very good protector, on which you can retouch very easily ; the only fault it has being its dearness. In 200 grm. of chloroform 2 grms. of ordinary gutta-percha (cut tine) are dissolved, then put to it 200 grm. of ether and 35 grm. of gum-dammar. Filter before use. This is a short account of my experience; I know it is not all new, but still I hope that this way of overcoming the frilling of plates is worth a trial. First, I used to put a little nitrate of silver to the finished emulsion, but found out that the plate became completely spoiled a month after. — o Zlotes. To-day is the last date for making application for space at the Brussels Photographic Exhibition ; the secretary is M. Geruzet, 27, Rue de 1’Ecuyer, Brussels. The German Photographic Society meet in conclave this year at Coblence, on the 22nd, 23rd, and 24th of August. Visitors are welcome. We are happy to present our readers this week with the City and Guilds Institute examination questions in photo graphy. M. Watery, of Paris, whose name is familiar as a portraitist of high rank, especially upon enamel, has opened a studio in Conduit Street. Mr. Thomas J. Pearsall, whose death occurred on the 25th inst., belonged to the old world of chemists. He was an original Fellow of the Chemical Society, and a Fellow of the Royal Society of Edinburgh. Not only did he claim respect as whilom an assistant of Faraday, but long before then he aided Brande, when the latter was professor of chemistry at the Royal Institution. It was, however, in connection with the London Mechanics’ Institution that Mr. Pearsall was best known, and where, indeed, the greater part of his life was spent. Of late years he interested himself much in photography; and his quaint familiar figure, hie