Procedure
Dissolve ca 1g of potassium sodium 2,3-dihydroxybutanedioate in ca 50cm3 of water in a beaker. Heat the solution to about 70°C. Add ca 20cm3 hydrogen peroxide solution and reheat to 70°C. Note any sign of a reaction. Dissolve ca 0.25g of cobalt(II) chloride in 5cm3 distilled water in a test tube and add to the hot reaction mixture. There will be an induction period before the reaction proceeds. As soon as the solution appears dark green, quickly transfer a small portion, using a teat pipette, into a test tube which is placed in a salted ice-bath.