Water 64 ounces f.
Protosulphate of iron 4 "
Acetic acid 4 "
Alcoholic solution of tannin, 10 grains
to the ounce 4 "
The four ounces of iron should be dissolved in the sixty-four ounces
(fluid) of water, and the acetic acid and tannic alcohol added.
In using this solution, develop your plate over a large filter,
which will receive all your surplus developing solution, and conduct
it into a bottle for use again; drain the plate into this filter
before washing, wash carefully and then place it into the fixing
solution--the developing solution which has filtered through into
the bottle is afterwards used in the proportion of one-half of old
to one-half of the new or fresh solution. This greatly improves the
high lights of the picture, and by using more or less of the old
solution, effects can be produced that are impossible by any other
means.
Great care should be taken to cause the developing solution to flow
evenly and with one sweep, as it were, over the whole surface, so
that the action may be as near as possible equal on all parts of the
surface.
In a very few seconds after the action of the developer has
commenced the picture will show up. The plate meanwhile should be
kept in motion and the [p020] solution caused to flow from side
to side and from one end to the other, in order that the development
may progress evenly and with the same speed on all parts.
The picture will gradually grow and brighten, until all the detail
that might be expected is seen in the shadows; then pour off the
remaining solution into the filter and proceed to wash the plate
until all traces of greasiness disappear; when the plate is
sufficiently washed and is ready to be fixed or cleared. Another
developing solution is prepared as follows:
Make a 64-ounce saturated solution of protosulphate of iron, into
which drop tannin solution enough to cause a precipitate, which
remains undissolved after shaking, then add drop by drop pure nitric
acid, until the precipitate is taken up and the solution becomes
clear. To one ounce of this add water, until it tests 18 to 20
grains to the ounce by the hydrometer, then add one ounce acetic
acid, which perfects the formula and constitutes the developer.