The Dictionary Of Photography

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

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For use mix equal parts ; for instantaneous work add 5 grs. or •3 grm. hypo to No. 2. Eikonogen is not easy to preserve in solution, or to get in solution, its solubility being low, only about seven grains per ounce of water; and, further, its avidity for oxygen is so great that it readily oxidises and turns brown, even in solution with a sulphite. The best preservative is acid sulphite of sodium or an acidulated solution of soda. A good formula for stock solution is Voight's, as follows: -
Acid Sulphite.
Sodium sulphite (crystals)... ... ... 170 grs.
Distilled water ... ...          to make 1 oz.
Hydrochloric acid............ 40 minims.
Dissolve in the above order.,
Stock Solution.
Eikonogen ... ... ...... ...     125 gr.
Sodium sulphite (crystals)... ... ...    625 ,,
Distilled water ... ...          to make ozs.
Acid sulphite as above ... ... ... 1 oz.
Dissolve in the above order. Another convenient formula is: -
Eikonogen ... ...        ... ... ... 125 grs.
Bi-sulphite of soda ...        ... ... ... oz.
Distilled water         ...        ...          to make 25 ozs.
For accelerators we may use either caustic alkalies or the car-bonates ; and having this choice gives us far more control over our negatives than would otherwise be the case. For ordinary work it is not advisable to use the caustic alkalies, and carbonate of soda may be used where soft results are desired, whilst potash gives us a little more contrast and density. One of the most important points when using eikonogen as a developer is the temperature of the solutions. At 320 F. its developing power is practically none, and its power increases with the rise of tem-perature : the temperature of the developer should be about 650 F. to obtain the best results. Briefly formulating a method of development with eikonogen, we arrive at the following conclu-sions : - Under-exposure and instantaneous shots : Use either of the caustic alkalies; or with extreme under-exposure or