| Neutral oxalate of potash | 1 lb. |
| Water | 5 pints. |
Acidify with oxalic acid and filter.
No. 2.
| Protosulphate of iron | 1 lb. |
| Water | 2 quarts. |
Filter and add 60 drops sulphuric acid.
No. 3.
| Bromide of Ammonium | 1 oz. |
| Water | 10 oz. |
The developer is prepared by mixing together in a p59 graduate the quantity necessary to cover the plate in the following proportions:
| Oxalate solution | 3 parts. |
| Iron solution | 1 part. |
| Bromide solution | 1⁄8 part. |
For instance, it will take about 8 ounces to cover an 8x10 plate in a flat dish; to make this quantity take of the