Chemistry for Photographers

Chemistry for Photographers

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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. 1902 edition. Excerpt: ...of the fingers with the fixing bath whilst toning is in progress. The chemistry of the toning process is as follows: In the alkaline solution the gold chloride is reduced first of all from auric chloride (AuCl3) to aurous chloride (AuCl); then an atom of gold is deposited, an atom of silver taking its place, thus, Aurous chloride. Silver. Silver chloride. Gold. AuCl + Ag AgCl + Au. From this it is clear that other metals can be used for toning instead of gold. With a platinum toning bath, for instance, platinum is deposited in the place of the silver, and with a lead toning bath, 94 GELATIN 0-CHLORIDE PAPER. lead is exchanged for the silver in the print. Tbe following platinum toning bath is recommended by Liesegang: --Potassium chloroplatinite, ..1 gram, J grain. Nitric acid, ....5 c.c, . 2 minims. Water, .... 100 . 1 oz. Gelatino-chloride and collodio-chloride papers are emulsions of silver chloride and an organic salt with gelatin in the one case and with collodion in the other. These papers are generally known as "printing-out" papers. W. K. Burton's formula for gelatino-chloride emulsions is as follows: --A. Ammonium chloride, 3'5 grams, . 53 grains. Gelatin, ... 27 . 420 Distilled water, . 850 c.c, . 30 ozs. Soak the gelatin and ammonia chloride in the water for an hour and dissolve in a water-bath; then add Silver nitrate, ..97 grams, . 150 grains. Distilled water, .14 c.c, . oz. B. Sodium citrate, . 2 grams, . 30 grains. Gelatin, ... 6'3 . 100 Distilled water, . 100 c.c, . 3J ozs. Allow to soak for an hour and dissolve in the water-bath; then add Silver nitrate, .. 3 grams, . 45 grains. Citric acid, . 5 . 80 Distilled water, . 14 c.c, . oz. COLLODIO-CHLORIDE PAPEK. Mix A and B; wash as directed in more

Product details

  • Paperback | 38 pages
  • 189 x 246 x 2mm | 86g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236593707
  • 9781236593702