THE FIXING SOLUTION

Consists of a solution of hyposulphite of soda in water, (filtered,) in the following proportion:—

Hyposulphite of Soda in crystals 8ounces.
Rain or Filtered Water1pint.

The Apparatus, &c. required in the Dry Collodion process is of the most simple kind, and consist of the following items

Glass plates.
Pneumatic plate holders.
Plate holder, for cleaning the plates.
Glass or porcelain dishes.
Glass or gutta percha dipping bath and dipper.
Silver hook, for lifting plates.
Levelling stand.
Measures, 1, 2, and 4 ounce.
Glass funnels.
Wash leather.
Some clean cloths and broad camel's hair brush.
Cotton wool.
Bibulous paper.
[A] The Chemicals are—
Nitrate of silver (fused.)
Glacial acetic acid.
Iodized Collodion (dry.)
Gelatine.
Citric Acid.
Alcohol.
Sulphuric æther.
Gallic acid.
Hyposulphite of soda.
Iodide of cadmium.
Benzoin varnish.

[A] The dry Collodion and the various solutions, ready for use, may be obtained of the Publishers.

In the above List we presume that the operator is in possession of a suitable camera and lens, and the usual adjuncts of camera tripod, &c. &c. These should all be of the best kind, otherwise it will be impossible to obtain good results.

THE MANIPULATION.

The process of obtaining a picture on Dry Collodion plates is in itself a most simple and easy matter, but there are one or two precautions that appear necessary to ensure success that cannot be lightly neglected. In the first place, it is absolutely certain, that if we want a clean and bright picture, we must have a plate perfectly free from all extraneous matters, such as soap, grease, &c. Various plans for cleaning the glass plate have been proposed, all more or less successful, but in most of them there is one great fault, namely, that of using a powder, as tripoli, rotten-stone, &c. to rub off the dirt with. Now we find that in practice this will not answer, from the almost impossibility of getting rid of the floating particles of the powder when the plate is rendered slightly electrical by rubbing, and as each of these particles if it become enveloped in the Collodion film, would produce a spot on the finished picture, we find it necessary to search in another direction for a detergent for the glass plate to which this objection would not apply. One soon presents itself in the form of old waste Collodion—this spread on the glass plate and rubbed off again with cotton wool, makes the best and most perfect cleanser hitherto proposed, without any of the objections usually appended to other materials used for the same purpose.

The next precaution necessary to be observed is, that all the solutions should be perfectly bright and clear; they should be absolutely free from floating particles of any kind. This is essential, as it is impossible to obtain clean pictures without attention to it; the floating bodies in the solution settle on the plate, and form so many nuclei, around which, in the development of the picture, the silver is deposited in an opaque mass, forming spots and blemishes on the surface of the plate.

There is one precaution that cannot be dispensed with, and that is, to be sure that the chemicals employed are of absolute purity; without this, success is very problematical, and vexation and disgust the sure reward of its neglect.

The process may for convenience be divided into the following stages:—

1.—Cleaning the plate.
2.—Coating it with Collodion.
3.—Rendering the plate sensitive.
4.—Applying the Preservative solution.
5.—Exposure in the camera.
6.—Development of the picture.
7.—Fixing the developed image.
8.—Varnishing the finished negative.