The photographic news

• Bandzählung: 29.1885
• Erscheinungsdatum: 1885
• Sprache: Englisch
• Signatur: F 135
• Vorlage: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: SLUB Dresden
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• Sammlungen: Fotografie
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12 THE PHOTOGRAPHIC NEWS. [January 2, 1885. effect the repeated transfer of the photographic picture by photo-mechanical means to the surfaces of large plates, drums, rolls, cylinders, or other forms of metal for the purpose of high or deep etching being produced thereon for printing in colours, calico printing, or other use. If the purpose for which the sheet so prepared be that of printing in colours from designs or pictures, upon the surfaces of cylinders or other forms, such sheet is, whilst still affixed on the glass plate, carefully and evenly covered or spread over with a thin, isolating film of raw collodion, and then with a thin solution of gelatine, applied by means of a sponge, a broad flat brush, or other vehicle adapted to the purpose, and is then allowed to dry freely and thoroughly. The gelatine solution just.referred to has been found well adapted to this purpose when prepared by the admixture with the gelatine of one-third part of alcohol, amd two per centum of alum ; but these proportions may be varied. This gelatine solution having been so applied, then that portion of the design or picture on the negative or sheet on which it is not desired that the colour shall appear, is covered or protected by the application of covering or blocking out ink or material. This application of blocking out or covering material is effected before the removal of the sheet from the glass plate or support. After the covering or blocking out material has become pro perly dry, the sheet or film is removed from the glass plate or equivalent support, and is applied and secured to the surface to which its application is desired, such as to the surface of a cylinder. After the surface, such as that of a cylinder or drum, has been prepared for the etching for the design for the first colour de sired, the prepared sheet or leaf may be again used for the pro duction of another similar design for the like surface of another cylinder or form, by stretching that prepared sheet or film on to a glass plate or equivalent surface, and securing it thereon, whilst the covering or blocking out material is being removed by spong ing or otherwise with benzine, turpentine, or other suitable sol vent, and then drying the sheet by means of blotting paper, or other suitable absorbent. The design or picture is then again covered with covering colour or blocking out material in such a way that only the por tions of the design desired for the next colour to be printed are left free or available for reproduction on the surface to be printed from or etched. The subsequent treatment will then be like that already described for the first colour surface. The like manipulations may then be similarly repeated for any further colour portions to be similarly represented by reserved portions of the design or picture on the surface, such as a printing cylinder, or drum or other form. The covering colour or reserving or blocking out matter should be so finely ground or reduced, and by admixture with benzine or other suitable solvent brought to such a consistency, that its most useful powers of attenuation may be secured. In order to render such large surfaces of sheet so prepared of greater usefulness, it becomes necessary to afford means of securing them on the surface whereon the design or picture is to be repro duced wholly or in part. The large negative or positive sheet of transparent material pro duced as described, is wound round or applied to the cylindrical or other contour of the surface desired to be etched in design, and such sheet having been so applied as tightly and evenly and flatly as possible by the use of suitable means of retention, not only enables a better result to be attained, but also permits of its re-use for a large number of times. In referring to hatching or graining, it is to be understood that by such term being used, no restriction is intended as to the character of pattern or effect which is referred to, as these will vary greatly with the nature of the design or picture, and such effects are variously denominated as hatching, cross hatching, stippling, graining, mezzotinting, lining, sanding, and other effects of a like nature. It is desired to be understood that no claim separately con sidered is made to the well-known process of making photographic dry plates or negative plates but that — Having now particularly described, and ascertained the nature of my said invention, and in what manner the same is to be per formed, I declare that what I do claim is— 1. The production of a grained or stippled surface upon a film or layer of chrome gelatine, or other similar substance, substan tially as and for the purposes firstly hereinbefore described. 2. The production of plates for photographic purposes wherein the sensitive film is combined with a grained, hatched, or engraved surface, substantially as and for the purposes hereinbefore secondly described. 13,372. William Charles Hughes, Optician, Brewster House, 82, Mortimer Road, Kingsland Hoad, N. London, “ An im proved frame for rapidly changing the pictures in a magic lantern.” Dated 9th October, 1881. The apparatus in question somewhat resembles that invented by Mr. Cowan, and described on page 146 of our volume for 1884; but the movement of the double holder is effected by a wheel and rack, and a shutter actuated by the wheel servesto cover the lens while the change of picture is being made. Patents Granted in America. 308,946. Solomon S. BESSTER, Toledo, Ohio. “ Photograph camera-plate holder.”—Filed April 19th, 1883. (No model.) Claim.—1. The combination in a photographic camera-plate holder, of the frame having parallel grooves in the inner faces of the sides of said frame, racks having a reciprocating motion in said grooves, and pinions engaging with said racks, whereby a simultaneous reciprocating movement of said racks is obtaine I in opposite directions, and the horizontal bars secured to said racks, the parts being constructed, arranged, and operating sub stantially as and for the purposes described. 2. The combination, in a plate-holder, of the horizontal bars secured to vertical racks, which are provided with means, sub stantially as described, for giving such racks a simultaneous re ciprocating movement in opposite directions, such horizontal bars being provided with adjustable rubber keys or stops, which have heads or shoulders, the parts being constructed, arranged, and operating substantially as and for the purposes specified. TESTING GELATINE. BY CAPTAIN ABNEY, B.E., F.R S.* Gelatine plate makers are fully aware that the quality of gela tine varies very considerably as regards the tendency to frill. It has often been thought that this tendency is simply dependent on the amount'of water which the gelatine will take up ; and no doubt, to a certain extent, this view is correct, but it is by no means universally true. When a gelatine lies on a plate the dry ing proceeds of course according to the temperature and dryness of the air with which it is surrounded; but it appears that different gelatines, under the same conditions, will dry in different times, and that the mere fact of drying puts a stress on the gelatine more in the plane of the plate than vertically to it. Under these cir cumstances, gelatines dried under the same conditions, as films on a glass? surface, will expand more or less in the direction of the surfacekof the plate ; and we may expect that the more a gelatine expands laterally, the more tendency there will be to wrinkle, blister, and frill. To test this, a series of plates were coated with different gelatines, five grains of each being spread evenly on j plates, and then dried in a drying cupboard. The films were then stripped off the plates, cut off, and measured accurately. Oue set of the measured gelatines was placed in water of 60° F., and allowed to swell for twelve hours. Another set was placed in water to which 6 drops of ammonia were added for every 2 ounces, which is about the strength of alkali in a deve- • Read before the Photographic Society of Great Britain,