Chemistry for photographers by William Ruthven FlintChemistry for photographers by William Ruthven Flint

Chemistry for photographers

byWilliam Ruthven Flint

Paperback | May 22, 2012

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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. 1920 Excerpt: ...ten to fifteen minutes and then treat them severally as follows. Take 50 cubic centimeters of water in a small tray, add a few drops of ammonium hydroxide, and put one of the plates into this solution. An immediate blackening of the bleached image will be noted. Dissolve 5 grams of sodium thiosulphate in 25 to 30 cubic centimeters of water, dilute to 50 and treat the second bleached plate with this solution. Here again will occur a darkening of the whitened portion. To blacken the third plate, use a regular developer solution. The three plates may now be well washed and dried, and the opacities of the unintensified parts compared. In explaining the chemical reactions which take place in this operation, we may first observe that there are two classes of mercury compounds representing two conditions of oxidation, namely, the mercuric salts, the higher condition, and the mercurous, the lower. Mercuric salts can be changed, by the action of reducing agents, to mercurous; and vice versa, the mercurous are oxidizable to mercuric compounds. Further, mercurous compounds are completely reducible to elementary mercury, and, when this reduction takes place from a solution of the mercury salt, the resulting mercury is in a very finely divided condition, and, since its absorption of all wave-lengths of light is very complete, its color is an intense black. Now, as we saw in the chapter on the photo-chemistry of silver salts, the silver of which the negative image consists is also in a fine state of division, and in this condition is a good reducing agent. Consequently, when mercuric chloride solution is applied to the negative, the silver reduces an equivalent amount of the mercuric chloride to mercurous chloride and is at the same time itself oxidized to silver chlorid...
Title:Chemistry for photographersFormat:PaperbackDimensions:54 pages, 9.69 × 7.44 × 0.11 inPublished:May 22, 2012Publisher:General Books LLCLanguage:English

The following ISBNs are associated with this title:

ISBN - 10:0217458629

ISBN - 13:9780217458627