Keep near at hand in a 64 oz. bottle this solution:
Protosulphate of iron 2 oz.
Citric acid 1 "
Water 64 "
and in a small bottle a ten-grain-to-the-ounce solution of silver
nitrate.
When a negative is to be strengthened, from the large bottle take
enough of the solution to cover the surface; to this add a half dram
of the silver and flow it over the negative.
A change of color will at once take place in the film, which will
become darker as the silver deposit becomes heavier; if one
application is not enough to secure the required density, wash the
plate and proceed again, as before. [p037]
Negatives may be strengthened before fixing, if it is found
necessary, by flowing the surface with the weak silver solution and
afterwards using the ordinary developer.
When one has become accustomed to the work, and can tell that the
negative is not dense enough before fixing, it is the best plan to
re-develop before fixing.
The mercurial intensifying solution for dry plates is very nice for
wet plates.
Having described the positive and negative collodion process, there
remains to give an account of the latest and greatest achievement in
photographic progress.
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