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EXPERIMENTS IN TONING GELATINO-CHLORIDE PAPER.


From the _Photographic News_ we take the following: The use of paper coated
with a gelatino-citro-chloride emulsion in place of albumenized paper
appears to be becoming daily more common. Successful toning has generally
been the difficulty with such paper, the alkaline baths commonly in use
with albumenized having proved unsuitable for toning this paper. On the
whole, the bath that has given the best results is one containing, in
addition to gold, a small quantity of hypo and a considerable quantity of
sulphocyanide of ammonium. Such a bath tones very rapidly, and gives most
pleasing colors. It appears, moreover, to be impossible to overtone the
citro-chloro emulsion paper with it in the sense that it is possible to
overtone prints on albumenized paper with the ordinary alkaline bath. That
is to say, it is impossible to produce a slaty gray image. The result of
prolonged toning is merely an image of an engraving black color. Of this,
however, we shall say more hereafter. We wish first of all to refer to an
elaborate series of experiments by Lionel Clark on the effects of various
toning baths used with the gelatino-citro-chloride paper.

The results of these experiments we have before us at the time of writing,
and we may at once say that, from the manner in which the experiments have
been carried out and in which the results have been tabulated, Lionel
Clark's work forms a very useful contribution to our photographic