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Samuel D. Humphrey

In the great catalogue of complaints made by operators, none is more common than that alleged against the quality of plates in general use. Although the greatest diversity of opinion exists upon this subject, nevertheless the plates of every manufactory share in this universal condemnation.

I do not give the method employed by our regular plate manufacturers; this is not important, as the operator could not possibly profit by it from the fact of the great expense of manufacturing. The following will be found practical:

M. Soliel has proposed the use of the chloride of silver to determine the time required to produce a good impression on the iodated plate in the camera. His method is to fix at the bottom of a tube, blackened within, a piece of card, on which chloride of silver, mixed with gum or dextrine, is spread. The tube thus disposed is turned from the side of the object of which we wish to take the image, and the time that the chloride of silver takes to become of a greyish slate color will be the time required for the light of the camera to produce a good effect on the iodated silver.


[From Humphrey's Journal, vol. ii 1851]

The following method of producing Daguerreotypes has by some been named as above. Most experienced operators have been long acquainted with the effect of the vapor of ammonia upon the chemically coated plate. I will here insert Mr. W. H. Hewett's plan of proceeding. This gentleman, in referring to it (published in 1845), says:

Coloring Back Grounds--Transparent ditto--Gilding Dissolvent Solution for removing Specks--Solarized Impression--To Purify Water--Cleaning Mercury--Adhesive Paper--Black Stain for Apparatus--Sealing Wax for Bottles--Rouge--Rotten Stone--Potassa Solution--Hyposulphite Solution--Substitute for do.--Gilding Solution--Solution for increasing the Brilliancy of the Daguerreotype--Bleaching Solution;--Cold Gilding--Neutralizing Agents--Buff Dryer--Keeping Buffs in order--Cleaning Buckskins--Reflector for taking Views.

In consideration of the importance of galvanized plates, I shall endeavor to give as plain and concise a manner of manipulation as possible. For some time it was a question among the operators generally, as to the beneficial result of electrotyping, the Daguerreotype plate, but for a few years past our first operators have found it a fact, that a well electro-silvered surface is the best for producing a portrait by the Daguerreotype.

Bromine and its Compounds--Iodine and its Compounds--Chlorine and its compounds--Cyanide of Potassium--Hyposulphite of Soda--Hyposulphite of Gold--Nitric Acid--Nitro-Muriatic Acid--Hydrochloric Acid--Hydrofluoric Acid--Sulphuric Acid--Accelerating Substances--Liquid Sensitives--Dry Sensitives, etc., etc.

To any desired quantity of chloride of silver in water add, little by little, cyanide of potassium, shaking well at each addition, until all the cyanide is dissolved. Continue this operation, and add the cyanide, until all the precipitate is taken up and held in solution.

This solution is now ready for the plate-cup. Enough water may be added to cover any sized plate when held perpendicular in the cup. The strength of the solution may be kept up by occasionally adding the chloride of silver and cyanide of potassium. There should alway be a very little excess of the cyanide.

Light--Optics--Solar Spectrum--Decomposition of Light--Light, Heat, and Actinism--Blue Paper and Color for the Walls of the Operating Room--Proportions of Light, Heat, and Actinism composing a Sunbeam--Refraction--Reflection--Lenses--Copying Spherical Aberration--Chromatic Aberration.

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