This formula also has the advantage, by gradually adding solution C, of controlling development up to the point desired, which is specially important for over-exposed plates. As the image loses on fixing, it is recommended to develop strongly.
For Bromide Paper. Both for prints and enlargements either of the above formulae may be used, and the freedom from stains will prove of great advantage. With diluted solutions clear grey tones are obtained.
For Chloride Plates and Lantern Slides. Transparencies of the blackest tones are developed with : -
Water ... ... ... ...... 20 ozs.
Sodium sulphite, cryst., pure ... ... 1 oz.
Amidol ............... 40 grs.
Warmer tones are obtained through longer exposure and the liberal addition of bromide, even up to one ounce in the four-ounce developer. Practically the ordinary methods of develop-ment may be followed with amidol - namely, for over-exposure, dilution of the developer with water, increase of bromide, or decrease of the accelerator; for under-exposure the contrary directions of course hold good. Amidol is likely to prove of great value especially in instantaneous work : it gives fine steely blue or grey-black images, and there is no tendency to stain. The author has found that for subjects with great contrasts, under-exposed plates, and portraiture, this developer will place a great power in the hands of the intelligent worker, because the images given are soft and harmonious, and one is thus enabled to intensify, to gain the requisite density, without getting harshness.
Ammonia (Ger., Wasseriges Ammonia, Salmakgeist; Fr. Ammoniaque; Ital., Ammoniacd). NH3 = I7. Is an extremely volatile, pungent gas, but is known to photographers as a solution in water, termed liquor ammoniae fortissimus. Specific gravity, "88o, containing about 35 per cent, of NH3. It should be kept in stoppered bottles, as the gas is freely evolved at ordinary temperatures, carbonic acid being absorbed from the air, forming carbonate of ammonia. It is used in alkaline development as an accelerator for pyrogallol. The fumes are extremely suffocating, causing sudden contraction of the glottis and consequent death is possible. Its use in ill-ventilated dark-