_Queries on Dr. Diamond's Calotype Process._--Would you kindly ask DR.
DIAMOND, to whom I should imagine all of us are more or less indebted, the
following questions respecting the very valuable paper on the calotype in
the last _Photographic Journal_?
1. As to the white spots which make their appearance in developing, on
Turner's paper especially, and which he says are owing to minute pieces of
metal in the paper, what is the best way of hiding them in the negative, so
that they may as little as possible injure the positive? I have suffered
sadly from this cause; and have tried to stop them with ammonio-nitrate,
which turns after a time to red, and stops the light effectually; but I
should prefer some black colouring the strength of which one could measure
by seeing its immediate effect.
2. And again, when one has black spots, what is the best means of lessening
their intensity, if not of wholly removing them?
[Greek: Photographos.]
[Where light spots occur in a negative, DR. DIAMOND recommends, as the
most effectual mode of stopping them, a little gamboge neatly applied
with a camel-hair pencil. Where a great intensity is desired, Indian
ink may be applied in the same manner, taking care in both cases to
smooth off the edges with a dry brush. The cyanide of potassium applied
in the same way, but _with very great care_, will remove the black
spots. Before it appears to have quite accomplished its object, a
negative should be immersed in water, as its action is so energetic.]
_Albumenized Paper._--I have followed DR. DIAMOND'S directions for
albumenizing paper (thin Canson negative) as accurately as I can, but I
cannot prevent the albumen in drying, when pinned up, from forming into
waves or streaks. This will be best understood from a specimen of a sheet
which I inclose, and I shall be much obliged if you can tell me how this
can be avoided. Some albumenized paper which I have purchased is quite free
from this defect, but being at a distance from London, it is both
convenient and economical to prepare my own paper.