Alum .... ............ 120 parts.
Copper sulphate ... ... ... ... 120 ,,
Common salt ... ... ...... 240 ,,
Water ...... ... ......1200 M
B. Saturated solution of common salt. Before use mix in equal parts and immerse in the solution till sufficiently reduced, then wash well.
Cyanide Reducers. Several formulae have been suggested for these, but their action is not to be depended upon.
Lainers Iodide Reducer. Lainer has suggested the follow-ing : -
Potassium iodide ... ... ... ... 10 grains.
Sodium hyposulphite ... ... ... 250 ,,
Water ............... ozs.
in which the negative is laid. Reduction takes place gradually and evenly.
The Persulphate Reducer. The reducer which is most even in its action on all parts of the negative is the persulphate of ammonium reducer; indeed, this reducer rather attacks the dense than the light portions of the negative, consequently it does not brighten the negative by unduly attacking the lighter gradations. For use one part of the persulphate of ammomium may be dissolved in from twenty to fifty parts of water. Imme-diate and thorough washing is required on removal of the negative from the persulphate bath, otherwise the action may continue.
The persulphate reducer is not suitable for reducing an ordinary over-exposed negative; the Howard Farmer's reducer being more specially useful in such a case, but the persulphate is of great value in the treatment of dense under-exposed negatives.
To Reduce Prints. Bromide prints may be reduced in exactly the same way as negatives. Albumenised Paper Prints may be reduced by dipping into cupric chloride, or by using the chloride of lime or platinum toning baths. To Reduce Ferro-Prussiate Prints, dip into a weak bath of liq. ammonia, and then into weak hydrochloric acid.
Reflected. Light is the light obtained by reflection from any mirror or white surface. It is extremely useful in portraiture for