Scientific American Supplement, No. 483, April 4, 1885 eBook

This eBook from the Gutenberg Project consists of approximately 99 pages of information about Scientific American Supplement, No. 483, April 4, 1885.

Scientific American Supplement, No. 483, April 4, 1885 eBook

This eBook from the Gutenberg Project consists of approximately 99 pages of information about Scientific American Supplement, No. 483, April 4, 1885.

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.

This solution will keep for ever, and will be sufficient to last two or three years, and with this at hand you will be able in two days to prepare a batch of plates at any time.  In doing so, you should proceed thus:  Make up your mind how many plates you mean to make, and take of the above accordingly.  For two dozen 1/2-plates or four dozen 31/4 by 31/4, dissolve by heat over, but not too near, a spirit lamp, and by yellow light, 40 grains of nitrate of silver in 1 ounce of alcohol 0.820.  While this is dissolving in a little Florence flask on a retort stand at a safe distance from the lamp—­which it will do in about 5 minutes—­take of the bromized solution 1/2 an ounce, of absolute ether 1 ounce, of gun-cotton grains; put these in a clean bottle, shake

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Scientific American Supplement, No. 483, April 4, 1885 from Project Gutenberg. Public domain.