When over-timing makes itself visible unexpectedly and it is feared that the development will have proceeded too far before the retarder can act, a good plan is to take the plate out of the dish and flow over it a solution of citric acid, containing a little chrome alum, p61 which will immediately stop the action of the developer and give time to make other arrangements.
AMMONIA PYRO DEVELOPER.
No. 1.
| Pyrogallic acid | 1 oz. |
| Alcohol | 4 oz. |
No. 2.
| Water | 60 oz. |
| Bromide of ammonium | 60 grs. |
| Strong liquor ammonia | 2 drs. |
To use, take of
| No. 1 or pyro solution | 1 dr. |
| No. 2 or ammonia solution | 10 oz. |
This will be enough to develop three or four 8×10 plates, if they are properly timed.
The above is one of the best forms of ammonia pyro developer; it gives negatives of very fine quality.