Part 338

I.—Pure water 30 ounces Sulphite soda, crystals 5 ounces Carbonate soda, crystals 2 1⁠/⁠2 ounces

II.—Pure water 24 ounces Oxalic acid 15 grains Pyrogallic acid 1 ounce

To develop, take of

Solution No. I. 1 ounce Solution No. II. 1⁠/⁠2 ounce Pure water 3 ounces

More water may be used in warm weather and less in cool weather.

If solution No. I is made by hydrometer test, use equal parts of the following:

Sulphite soda testing, 80°. Carbonate soda testing, 40°.

One ounce of this mixture will be equivalent to 1 ounce of solution No. I.

«Pyro and Potassium Developer.»—

I.—Pure water 32 ounces Sulphite soda, crystals 8 ounces Carbonate potassium, dry 1 ounce

II.—Pure water 24 ounces Oxalic acid 15 ounces Pyrogallic acid 1 ounce

To develop, take of

Solution No. I. 1 ounce Solution No. II. 1⁠/⁠2 ounce Pure water 3 ounces

When the plate is fully developed, if the lights are too thin, use less water in the developer; if too dense, use more water.

«Pyro and Metol Developer.»—Good for short exposures:

I.—Pure water 57 ounces Sulphite soda, crystals 2 1⁠/⁠2 ounces Metol 1 ounce

II.—Pure water 57 ounces Sulphite soda, crystals 2 1⁠/⁠2 ounces Pyrogallic acid 1⁠/⁠4 ounce

III.—Pure water 57 ounces Carbonate potassium 2 1⁠/⁠2 ounces

To develop, take of

Pure water 3 ounces Solution No. I. 1 ounce Solution No. II. 1 ounce Solution No. III. 1 ounce

This developer may be used repeatedly by adding a little fresh developer as required.

Keep the used developer in a separate bottle.

«Rodinal Developer.»—One part rodinal to 30 parts pure water.

Use repeatedly, adding fresh as required.

«Bromo-Hydrochinon Developer.»—For producing great contrast and intensity, also for developing over-exposed plates.

I.—Distilled or ice water 25 ounces Sulphite of soda, crystals 3 ounces Hydrochinon 1⁠/⁠2 ounce Bromide of potassium 1⁠/⁠4 ounce

Dissolve by warming, and let cool before use.

II.—Water 25 ounces Carbonate of soda, crystals 6 ounces