The Dictionary Of Photography

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

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Isotype                                                        Ivory Black
Schumann's Cyanin Bath.
Soak the plate in I or 2 per cent, of ammonia solution for two or three minutes ; then immerse in -
Alcoholic solution of cyanin (i in 500) ...     168 mins.
Ammonia ... ... ... ...... 68 ..
Alcohol         ...............    168 ..
Distilled water ... ... ...... 7 ozs.
for not more than 100 seconds, drain and dry.
Bothamley's Sensitiser for Pictures.
Solution of rose Bengal (1 in 1,000) ... 10 parts.
Solution of cyanin (1 in 2,000) ...... 10 ,,
Solution of erythrosin (1 in 2,000)           ... 10 ..
made alkaline with 1 per cent, of ammonia. These are the principal baths, and from these others may be used, which may be made on the above lines. Mr. F. E. Ives made numerous and early experiments on the colour sensitising of collodio-bromide, and found that the best results were obtained by flowing over the coated plate, as soon as the collodion has set, a strong alcoholic solution of chlorophyll, obtained by digesting blue myrtle or the periwinkle {vinca major) leaves in alcohol, then immersing the plates in water strongly tinted with blue shade eosin, and drying. This process is said to render the plate sensitive for the whole range of the spectrum.
Isotype. A term applied to a certain method of using a doubly perforated diaphragm with the screen (see Fish Glue Process) in process work.
IT. Captain Abney proposes the term " IT " (initials of in-tensity and time) as an expression of the unit of exposure. (See The Amateur Photographer, October 23rd, 1896, p. 339.)
Ivory. The teeth and tusks of the elephant and walrus. Photographs can be obtained on ivory by coating with an emulsion or by transfer as in the carbon process. Various arti-ficial substitutes have been used, such as insoluble gelatine or celluloid containing a white pigment.
Ivory Black. Made by calcining ivory in close crucibles used as an ingredient for black varnish and a pigment.
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