The Photographic News; A Weekly Record of the Progress of Photography Volume 10

The Photographic News; A Weekly Record of the Progress of Photography Volume 10

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1866 edition. Excerpt: ... its nature by the action of tho light, yet tho effect of this change will only bo apparent when it is brought into connexion with somo organic substanco which shall, in combining with it, change its colour, at tho same time leaving without change that portion of silver not touched by light. The substanco most easily and inexpensively employed for this purpose is gallic acid, of which a solution is mado by simply filling a bottle with distilled water and throwing into it Bomo gallic acid till tho water is saturated, ensuring always that it is so by taking care that some grains remain at tho bottom of the bottle. To inako this solution with cold distilled water it is reqnisilo that the water should remain in contact with the acid at least twenty-four hours. Two ounces fluid of this solution is poured into a glass dish, and to it is added fifteen drops of a solution of nitrate of silver--twenty grains silver to ono ounco of water. Into this tho plate, after being taken from the slide, is immersed, care being taken that the immoreion bo dono so that tho solution contained in tho dish flows over tho plate immediately, without leaving any dry places. Aftor about a quarter of an hour tho image will be seen upon the plate, or, in photographic language, "tho image will develop itself in all its details, under the influence of tho developer." It will only then bo necessary to increaso tho intensity, or, in ordinary words, to inako tho imago blacker, by adding about fifteen to twenty drops of tho same solution of silver to the developing solution in the tray; about a quarter of an hour or twenty minutes will bo quite sufficient, and if it is not required to print from, tho plate may be washed with a little water and allowed to dry. To use the...show more

Product details

  • Paperback | 832 pages
  • 189 x 246 x 42mm | 1,456g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236507142
  • 9781236507143