Dyeing with indigo.

The Galaxy 3, 1873

A discovery of a considerable interest for the art of dyeing has recently been made by M. Schützenberger, of the Paris Chemical Society, and his colleague F. de Lalande. In the usual method of dyeing blue with indigo, a solution of white or reduced indigo is employed, in some alkaline fluid. On exposure to the air, goods treated with this solution become blue, owing to the oxidation of the dye. The waste attending this process is very great. But Schützenberger and Lalande find that in connection with alkalis or alkaline bodies the hydrosulphite of soda very readily reduces indigo at a high or at a low temperature. Thus a blue color may be given to fabrics without having a recourse to oxidation, a saving is effected of over 50 per cent. of indigo, any furthermore goods may be dyed indigo and other colors at once. This method is in actual operation at Rouen.