No. 1. Clear liquor, 1° to 2° B. (strongest).
No. 2. Black ash sludge (weaker than No. 3).
No. 3. Black ash, after sending up to causticising-tank (strongest sludge).
No. 4. Fresh black ash.
No. 5. Weaker than No. 2 (sludge only).
No. 6. Weaker than No. 5 (sludge and weakest liquor).
The method of procedure is as follows:—
Liquor from No. 3 drained into No. 1 (now full).
No. 6 pumped on to No. 2 (No. 6 sludge thrown away).
Liquor from No. 2 drained upon No. 3.