Page 24 - The Wellington photographic handbook

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PYRO-AMMONIA.*
No. 1.
Pyrogallic Acid 1 ounce 50 grammes
Sodium Sulphite (cryst.) ... 2 ounces 100
:.)
Citric Acid 40 grains 4-5 „
1 V ounces
Water to 10 500 c.c.
No. 2.
Ammonia -880 1 ounce 50 c.c.
Water to ... IU 0 ounces 500 c.c.
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No. 4.
Ammonium Bromide . . 1 ounce 50 grammes
Water to 1 0 ounces 500 c.c.
Take 10 drops of No. 1, 10 drops of No. 2, and 5 drops of No. 3 to each
ounce (30 c.c.) of Water.
COMPOUNDING THE DEVELOPER.
In making up the pyro-soda formula the sulphite and citric
acid should be allowed to dissolve in from 4 to 5 ounces of hot water.
When cool the pyro should be added, and the solution diluted with
cold water to make 10 ounces in all. It will keep all the better
if it is made up with water that has been boiled briskly and allowed
to get cold without agitation. The carbonate and sulphite solution
can be made with hot water also. Neither must be used until quite
cold. In a well-corked bottle, the pyro solution will keep for a
couple of months at least, and as long as it shows no more than a
slight yellow discoloration may be regarded as in good working
order. An old No. 2 solution tends to give yellow negatives.
If preferred potassium metabisulphite may be substituted for
citric acid and sodium sulphite as the preservative in the pyro
solution. Sixty grains should be dissolved in cold or warm—not
hot—water, and the pyro added as described above.
Water previously boiled should also be used for mixing the
metol-hydroquinone developer. It is important that the metol
should be completely dissolved before the other ingredients are
added. Metol does not readily dissolve in the presence of sodium
sulphite and any undissolved particles will probably remain in
suspension until they become deposited upon the plates during
development, giving rise to a plentiful crop of black spots. Warm
water is to be preferred for making up the solution.
* Before making up any formula, read the notes on pages 125, 126 and 134.
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