3. Ground in the discharge No. 2.; dry.
4. Clear off the paste in chalky water.
5. Dung, madder, and brighten.
6. Ground-in the topical colours at pleasure.
V. China blues.
Take 16 pounds of coarsely ground indigo, and
4 pounds of sulphuret of arsenic; dissolve 22 pounds of sulphate of iron in 6 gallons of water; introduce these three matters into the indigo mill, and grind them for three days. If it be wished to have a thickened blue, this mixture must have pounded gum added to it, but if not, 5 gallons of water are added. This colour may be called blue No. 1.
The following table exhibits the different gradations of China blue:—
| Course. | Quantity by measure of No. 1. | Quantity by measure of water or mucilage. | |
|---|---|---|---|
| No. | 1 | 1 | 0 |
| 2 | 11 | 1 | |
| 3 | 10 | 2 | |
| 4 | 8 | 4 | |
| 5 | 6 | 6 | |
| 6 | 4 | 8 | |
| 7 | 2 | 10 | |
| 8 | 2 | 12 | |
| 9 | 2 | 14 | |
| 10 | 2 | 16 | |
| 11 | 2 | 18 | |
| 12 | 2 | 20 | |
I shall now give examples of working this style by the block and cylinder:—
Impression of a single blue with small dots.
For the block, blue No. 5. thickened with starch.
For the cylinder, No. 4. thickened with gum.