Jewellers' Rouge Precipitated from Copperas, Ure 1839

Rouge is fine red iron oxide, the last polish for metal and lenses. Ure (1839) gives the best polishing powder: add soda solution to copperas solution, wash and dry the precipitate, and heat it gently in shallow vessels until it turns a deep brown red. Grind and wash it fine, and bind some in wax and tallow as a bar. The picture: iron(III) oxide powder.