Chemicals: potassium sodium tartrate, hydrogen peroxide, copper sulphate.
Procedure: A solution of 17 g of tartrate in 60 ml of water and 40 ml of 3% hydrogen peroxide. These solutions were combined and heated to 50 ° C and add 1 ml of a 1M solution of copper sulphate solution. Immediately there is a yellow color of the solution from escaping as bubbles of soda. At 20-30 ° C, the solution discolour very slowly.