Wilson's Cyclopedic Photography: A Complete Handbook of the Terms, Processes, Formulae and Appliances Available in Photography, Arranged in Cyclopedic Form for Ready Reference

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E. L. Wilson, 1894 - 464 pages
 

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Page 110 - ... ground, which at a certain moment possesses a high degree of sharpness, and singular beauty and delicacy of tint. If at this instant it be thrown into water, it passes immediately...
Page 110 - has been given by Berzelius. If (to render my meaning more clear) we for a moment consent to designate such an isomeric form of iron by the name siderium, the oxide in question might be regarded as a sideriate of iron. Both phosphorus and arsenic (bodies remarkable for sesqui-combinations) admit isomeric forms in their oxides and acids. But to return from this digression. " If to a mixture of ammonio-citrate of iron and sulphocyanate of potash, a small dose of nitric acid be added, the resulting...
Page 387 - ... which had any influence on the metal were the calorific rays. This experiment was repeated on different metals, and with various materials, the plate being exposed to steam, mercury, and iodine: I invariably found that those bodies which absorbed or permitted the permeation of the most heat gave the best images. The blue and violet rays could not be detected to leave any evidence of action, and as spectra imprinted on photographic papers by light, which had permeated these glasses, gave evidence...
Page 296 - PRECIPITATE. — A substance, which, having been dissolved,, is again separated from its solvent and thrown to the bottom of the vessel, by pouring another liquid upon it.
Page 63 - The most perfect pictures are those which " come out" before any part of the paper becomes dry, which they will do if sufficiently impressed in the camera. If the paper be allowed to dry before washing off the gallo-nitrate, the lights sink and become opaque ; and if exposed in the dry state to heat, the paper will embrown ; the drying therefore ought to be retarded, by wetting the back of the paper, or the picture may be brought out by the vapour from hot water, or what is better, a horizontal jet...
Page 360 - ... constantly before him, its position remaining unchanged in respect of space, but its parts will appear to be in motion, and in solid relief, as in the veritable object. The stationary appearance of the pictures, notwithstanding the fact of their being in rapid motion, is brought about by causing their corresponding parts to be seen, respectively, only in the same part of space, and that for so short a time that while in view they make no sensible progression. As, however, there is an actual progression...
Page 33 - The petals of the fresh flowers, or rather such parts of them as possessed a uniform tint, were crushed to a pulp in a marble mortar, either alone, or with addition of alcohol, and the juice expressed by squeezing the pulp in a clean linen or cotton cloth. It was then spread on paper with a flat brush, and dried in the air without artificial heat, or at most with the gentle warmth which rises in the ascending current of air from an Arnott stove.
Page 387 - ... contact. The image of the glass only could be brought out. 15. A design cut out in paper was pressed close to a copper plate by a piece of glass, and then exposed to a gentle heat ; the impression was brought out by the vapour of mercury in beautiful distinctness.
Page 360 - ... by means of an endless band. The eye-cylinder thus making four revolutions to one of the picture-drum, it is evident that the axes of its apertures will respectively coincide with the plane of sight four times in one complete revolution of the instrument, and that, consequently, vision will be permitted eight times, or once for each picture. The cylinder is so placed that at the time of vision the large ends of the apertures are next the eyes, the effect of which is that when the small ends pass...
Page 84 - A very short exposure of the paper washed with this solution is quite sufficient to discharge all the yellow from the paper and give it perfect whiteness. If an engraving is to be copied we proceed in the usual manner; and we may either bring out the picture by placing the paper in a solution of carbonate of soda or potash, by which all the shadows are represented by the chromate of copper, or by washing the paper with nitrate of silver. It may sometimes happen that, owing to deficient light, the...

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