Fifthly. The film is peeled off the paper by hand, and can be
immediately used for producing negatives _recto_ or _verso_ as above
mentioned.
I claim as my invention:
First. The preparation or formation of gelatino-bromide film paper
for photographic negatives, in the manner and for the purposes above
described; and,
Secondly. The use for this purpose of castor oil, or any other analogous
oil, more especially with the view of peeling off the film from the
paper backing as above described.
* * * * *
SOME OF THE USES OF COMMON ALUM.
A substance very much used by photographers of late years--in fact, so
much used that no well-appointed laboratory could be considered complete
without it--is the substance known is common alum, or potash alum, being
a double sulphate of alumina and potash; but it is interesting to note
that much of the commercial alum met with at the present time is ammonia
alum, or the double sulphate of alum and ammonia. It is quite a matter
of indifference to the photographer whether he uses potash alum or
ammonia alum.
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