Division 4.1 Clarification agent: basic lead acetate solution.

Add 560 g of dry basic lead acetate to about 1 000 ml of freshly boiled water. Boil the mixture for 30 minutes and then leave it to stand overnight.

Decant the supernatant liquid and dilute with freshly boiled water to obtain a solution of density of 1·25 g/ml, at 20 ^oC.

Protect this solution from contact with air.