The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Objective
Opalotype
chlorine unites with the copper and etches it to a greater or less degree, according to the depth of deposit of silver chloride. The result is a grained intaglio plate of extreme delicacy and beauty, which is inked and printed from the same as any other intaglio plate.
Objective. A term sometimes applied to the image-forming lens of an optical instrument, as for example the lens used with the photographic camera. (See Lens.)
Oil of Lavender. This and the oil of the spike lavender were used as solvents in the early forms of the bitumen process.
Oil of Spike. See Oil of Lavender.
Oil Paintings, to Copy. See Copying.
Opacity. See Density.
Opalotype. A term applied to pictures on opal glass. They can be made by coating opal glass with a plain gelatino-bromide emulsion, or by using a printing-out emulsion. The exposure and development are the same as for bromide paper. Either polished or ground opal glass may be used, the latter giving very pleasing pictures of a matt surface. Another method of obtaining pictures by the printing-out process is by the use of a collodio-chloride emulsion, which may be made as follows: -
No. i. Silver nitrate            ... ... ...        ... 31 grs.
Methylated alcohol......... ... 28 drms.
Dissolve by the aid of heat immediately before using.
No. 2. Strontium chloride ... ... ... ... 31 grs.
Methylated alcohol ... ...... ... 28 drms.
No. 3. Citric acid ... ... ...        ... ... 31 grs.
Methylated alcohol ... ... ... ... 28 drms.
No. 4.
Pyroxyline or celloidin ... ... ...      62 grs.
Methylated alcohol............      28 drms.
..          ether ... ........,      28 ,,
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