Scientific American Supplement, No. 483, April 4, 1885Various
Science
Scientific American Supplement, No. 483, April 4, 1885
Various
Science -- Periodicals
It is not my desire to enter into any discussion as to this or that being
the best means of producing these delightful pictures, but merely to
describe a way by which a pleasant evening can be spent at photography,
and slides produced of much excellence by artificial light.
To-night I propose, by the aid of artificial light, to make a few slides
with Beechy's dry plates. On the whole, I have been most successful with
them, and have obtained results more satisfactory than by any of the
other processes I have tried. I do not say that results quite as good
cannot be obtained by any other method, for I know manipulative skill
plays a most important part in this class of work.
When I first took up the making of transparencies with wet collodion, I
was told that my sorrows would not be far to seek, and so I soon found
out. Need I tell you of all my failures, such as films floating off the
glass, oyster-shell markings, pin-holes, films splitting when dry, etc.,
etc., not to speak of going to business with fingers in fearful state
with nitrate of silver and iron developer? Now all these miseries have
gone, and I can, with dry collodion plates, work with the greatest of
comfort, and obtain results quite equal to the best products of any
method.
It may be interesting to some to know the formula by which the emulsion
is made, and as the making of it is by no means a difficult operation, I
may be pardoned if, before going fully into the more practical part of my
paper, I describe the formula, and also the manner in which I coat and
dry the plates. The formula is as follows, for which the world is
indebted to Canon Beechy:
In 8 ounces of absolute alcohol dissolve 5 drachms of anhydrous bromide
of cadmium. The solution will be milky. Let it stand at least twenty-four
hours, or until perfectly clear; it will deposit a white powder. Decant
carefully into an 8-ounce bottle, and add to it a drachm of strong
hydrochloric acid. Label this "bromide solution;" and it is well to add
on the label the constituents, which will be found to be nearly:
Alcohol. 1 ounce.
Bromide of cadmium. 32 grains.
Hydrochloric acid. 8 drops.
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