767. The quantity of sodium sulphite in the developer must be regulated to produce the color desired. It is to the 11 - 16 photographer's advantage, when using pyro developer, to use our formula, as most other formulae call for more pyro than is necessary for our plates.

Pyro and Soda (By Weight).

No. 1

English Weights and Measure.

Metric Weights and Measure.

30 ounces pure water

.or 900 c.c.

5 ounces Sodium Sulphite (crystals). .

.or 150 grammes

21/2 ounces Sodium Carbonate (crystals) .

.or 75 grammes

No. 2

24 ounces Pure water

. .or 720 c.c.

15 grains Oxalic Acid (dissolved).......

..or 1 gramme

And then add -

1 ounce Pyrogallic Acid

or 30 grammes

To develop, take :-

1 ounce of Solution No.1

or 30 c.c

1/2 ounce of Solution No.2

. .or 15 c.c.

6 to 8 ounces Pure water

or 180 to 240 c.c.

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

768. Pyro Developer with Carbonate of Potash.

No. 1

English Weights and Measure.

Metric Weights and Measure.

32 ounces Pure water

.. .or 960 c. c.

8 ounces Sodium Sulphite (crystals) .

. . .or 240 grammes

1 ounce Carbonate of Potash (dry) ..

.. .or 30 grammes

No. 2

24 ounces Pure water................

...or 720 c.c.

15 grains Oxalic Acid (dissolved first). .

or 1 gramme

1 ounce Pyrogallic Acid

or 30 grammes

To develop, take : -

1 ounce of Solution No. 1.............

. . .or 30 c.c.

1/2 ounce of Solution No. 2.............

.. .or 15 c.c.

6 to 8 ounces of Pure water...........

or 180 to 240 c.c.

When the plate is fully developed and you find the highlights too thin, use less water in the developer; if too dense, use more water.

769. Pyro and Soda. ( Three solutions by weight and by hydrometer.)-This formula is better suited to all localities than is a two-solution developer. Each property of the developer being separate, the user can vary the quantity of either to meet local conditions. The water in some places is alkaline; then less of No. 2 Carbonate of Soda should be used. A few trials will indicate the amount that should be used in order to produce the best results. In cold weather the carbonate of soda can be increased a little. During hot weather it is generally best to use a little less of the No. 2 solution, for if the temperature is very high and too much of this chemical is present, the user will destroy the clearness of his plate. The sulphite being in a separate (No. 1) solution, the user can easily modify results by varying the proportion. The water in some localities does not require as much sulphite as in others. Use just enough of the sulphite solution to give the proper printing color to the negative (just a trace of yellow).

No. 1

English Weights and Measure.

Metric Weights and Measure.

15 ounces of pure water

or 450 c. c.

5 ounces Sulphite of Soda (crystals)

or 150 grammes

Hydrometer test eighty degrees.

No. 2

15 ounces of Pure water

or 450 c. c.

21/2 ounces Carbonate of Soda ( crystals )

or 75 grammes

Hydrometer test forty degrees.

No. 3

24 ounces of pure water

or 720 c.c.

15 grains Oxalic Acid

or 1 gramme.

1 ounce Pyrogallic Acid

or 30 grammes.

To Develop, Take:

1/2 ounce of each, No. 1, No. 2, No. 3

........or 15 c. c.

6 to 8 ounces Pure water

or 180 to 240 c.c.

770. If the subject has strong contrasts of light and shadow, use a little less of No. 3 and a little more water than usual.

771. If the subject is flat and lacking in contrast, increase the amount of No. 3 and use a little less of No. 2; a few drops of bromide solution will be beneficial.

772. Keep developing solutions cool and use more water in hot weather.

773. Do not use a cold developer in cold weather. The water may be decreased when the temperature is low.

774. For Non-Halation (double-coated) Plates, use about one-third more water; the development will be slower, but the results will justify the extra time spent in this way.