| II.— | Oxalic acid | 5 parts |
|---|---|---|
| Ammonium chloride | 10 parts | |
| Acetic acid, 30 per cent dilution | 500 parts |
Mix and dissolve. Use as above indicated. The following will produce the same result:
| III.— | Potassium oxalate, acid | 4 parts |
|---|---|---|
| Ammonium chloride | 16–17 parts | |
| Vinegar containing 6 per cent of acetic acid | 1,000 parts |
IV.—Bluish Green.—After using the first formula (for green) pencil over with the following solution:
| Ammonium chloride | 40 parts |
| Ammonium carbonate | 120 parts |
| Water | 1,000 parts |
Mix and dissolve.
Greenish Brown.—
| V.— | Potassium sulphuret | 5 parts |
|---|---|---|
| Water | 1,000 parts |
Mix and dissolve. With this, pencil over object to be treated, let dry, then pencil over with 10 parts a mixture of a saturated solution of ammonia water and acetic acid and 5 parts of ammonium chloride thinned with 1,000 parts of water. Let dry again, then brush off well. Repeat, if necessary, until the desired hue is attained.
Another Blue Green.—