In a glass beaker dissolve 2 dr. silver nitrate in 1 1/2 dr. distilled water by heat; drop this solution into a bottle containing 14 dr. alcohol. In cold weather it is better to put the bottle in a vessel containing warm water; then add 2 dr. soluble cotton, and, after thorough shaking, 16 dr. ether. On further shaking, a greyish-white collodion will form itself. In another bottle dissolve 1/4 dr. lithium chloride in 9 dr. alcohol, together with 1/4 dr. tartaric acid. This solution is to be dropped into the argentiferous collodion, which must be shaken all the while. This collodion will keep for any time if preserved in a well-corked black bottle or in a fitting dark cover.

Have a thin piece of wood, same size as the paper that is to be coated, with a knob fastened at the under side; pin the lichtdruck paper on it at 3 of the corners, so that the right and lower edge project a little over the wood (this will cause the collodion not to run under the paper), and the left edge of the paper may be turned up a little; but this will not be found necessary after some practice. Now hold the wood with the left hand by the handle, as you would take a glass plate fixed to a pneumatic plate-holder, and pour the collodio-chloride upon the paper just as you would coat a glass plate with collodion. Having returned the surplus of the collodion to the bottle, take the pins away and hang up the paper to dry. The paper will keep for several weeks.

Some prefer to use a pink-coloured lichtdruck paper, whose colour will obliterate any trace of yellow that might form by keeping it for a longer period.

The printing must be done in the shade, and weak negatives are better covered by thin, white paper during printing. Toning may be done in an old gold bath that is not too strong. German photographers prefer the following : Make 2 stock solutions - one of 1/4 dr. gold chloride in 3 pints water; and one of 5 dr. potassium sulphocyanide, 3/4 dr. soda hyposulphite, and 1/4 dr. soda carbonate in 3 pints water. Before going to work, mix equal parts of these solutions, but be sure to pour the gold into the sulphocyanide solution, not vice versa.

After having washed the prints in water 3 times changed, put them in the gold bath. If it work too quickly, it will give grey tones. Dilute with water that it may act more strongly; and for weak negatives pass the prints before toning through a 2 per cent. solution of potassium sulphocyanide, the prints becoming of a much richer tone by this. Fix in a 5 per cent. solution of soda hyposulphite (5 minutes will be sufficient), and wash for one hour in water frequently changed.

To make the prints look like enamelled silver prints: clean a sheet of glass, a little larger than the print, and rub it with French chalk; after dusting it off with a brush, lay the print, film side down, on the glasses; put some filtering paper upon it, and go over it with the hand to make the print adhere and to remove air-bubbles. Allow it to dry, and the print will come away with a very high gloss. A part of this it will lose on mounting; but if you mount it at the corners only, as is sometimes done with enamelled prints, it will retain it all. (E. Liesegang.)

Example of Collodion process. Cleaning the plate. - For polishing the glass plate use

Iodine.. .. .. .. 1 dr.

Tripoli . .. .. .. 3 oz.

Methylated spirit .. 1 pint

Collodionising

Care is to be taken that the back and edges of the plates are freed from dirt and dust previous to coating, and that the collodion film is allowed to set well before placing in the bath.

Silver Bath

When compounded of pure silver nitrate and distilled water, as a rule, will work well at once, but sometimes a trace of nitric acid is required so as to make the liquid slowly turn the colour of blue litmus to red.

Silver nitrate ......... 1 oz.

Distilled water...... 12 oz.

Nitric acid (if required) about 1 drop.

Developer

The best and handiest method of compounding the developing solution is to keep a standard solution of iron sulphate.

Iron sulphate .. 10 oz.

Water........ 20 oz.

Copper sulphate .. 1 oz.

To make a 20-gr. developer, take

Of the above .. .. 2 oz. Glacial acetic acid .. 6 dr. Water........ 18 oz.

Alcohol is required to make the solution flow easily over the plate; about 1 oz. to each pint of developer.

More or less of the standard solution of iron is used as a stronger or weaker developer is required. In the case of under-exposure, a strong developer is very handy to bring out detail and promote harmony; for over-exposure, the negative should be fixed, very thoroughly washed, and intensified afterwards.

In photographing a subject presenting violent contrasts, the use of a strong developer will tend to promote harmony in the negative, and on a subject where the general effect is flat, a weak solution will give a brighter picture.

Intensification

This is rarely necessary. If, however, it is needed, subjoined are the formulae: -

Pyrogallic acid .. .. 40 gr.

Citric acid...... 20 gr.

Water........ 20 oz.

This solution will not keep long: it is to be used with a few drops of a 30-gr. solution of silver nitrate added to each ounce.

Fixing may be accomplished in either potassium cyanide, 20 gr. to each ounce, or in soda hyposulphite, 70 gr. to each ounce; but if the latter be used, more copious washing is required than when cyanide is used.

Varnishing

Take

Sandarach...... 3/4 lb.

Shellac ...... 2 oz.

Place in a bottle, cover with absolute alcohol, allow to digest for 2 days; pour off the liquid portion into a Winchester, add more absolute alcohol, and again digest for 3-4 days, stirring or shaking occasionally; now mix with that already in the Winchester; add 1 oz. castor oil, shake well, and dilute by filling up the Winchester with methylated spirit; allow to stand, and settle. A Winchester is a stoppered glass bottle holding 1/2 gal.