The Dictionary Of Photography

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

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Tragacanth(Ger., Tragant, Tragantschtcim ; Ft., Adfragante ; ItaL, Dragante). A gummy exudation from the stem of Astrag-alus verusy collected in Asia Minor. It should be nearly white, and sparingly soluble in cold water; more so in hot; entirely insoluble in alcohol.
Transfers. By this term is meant the pictures produced by transferring an image developed upon a temporary support, and affixed afterwards to its final support. These are usually made by the carbon or collodion process ; but lately a special trans-ferotype paper has been introduced, which gives very pleasing effects. This consists of a film of insoluble gelatino-bromide emulsion, affixed to a temporary support of paper by a soluble substratum. The method of exposure and after-treatment is precisely the same as for bromide paper, but they can be toned after transfer by the following process : -
Solution A.
Ferricyanide of potash ... ......ioo grs.
Distilled water ............24 ozs.
Solution B.
tJranic nitrate          ...... ... ... 100 grs.
Distilled water         ............24 ozs.
Keep these separate, and mix only for immediate use. Take equal parts of A and B, mix, and immerse the transferred picture in the bath till the desired tone is obtained. Fix again in
Hyposulphite of soda         ... ... ... 3 ozs.
Water            ............... 16 ..
The darker the print the deeper the tone. As this process intensifies (it is practically nothing but uranium intensification) medium light prints give the best results. The above formula gives warm red tones; for rich browns, leave the prints in toning solution till they begin to turn ; then immerse in weak alum solution, wash, and fix. To transfer these, lay the wet print upon the surface to which it is to be transferred, which may be either polished or ground opal glass, clear or ground glass, porcelain, wood, ivory, canvas, or any other materia which will stand hot water. The surface must be perfectly free from grease or dirt; squeegee the wet print carefully on to it,