Division 4.1 Copper II solution (Muller's solution)

Dissolve 35 g of copper II sulphate, pentahydrate (CuSO₄.5H₂O) in 400 ml of boiling water. Allow to cool.

Dissolve 173 g of sodium potassium tartrate tetrahydrate (Rochelle salt or Seignette salt; KNaC₄H₄O₆4H₂O) and 68 g of anhydrous sodium carbonate in 500 ml of boiling water. Allow to cool.

Transfer both solutions (4.1.1 and 4.1.2) to a one litre volumetric flask and make up to one litre with water. Add 2 g of activated carbon, shake, allow to stand for several hours and filter through thick filter paper or a membrane filter.

If small amounts of copper I oxide appear during storage, the solution should be re-filtered.