In 1862 Field gave a brief account of a peculiar green solution, prepared by adding nitrate of cobalt to a solution of bicarbonate of soda containing a small quantity of the hypochlorite of that alkali. The author observed the formation of a similar green solution when making qualitative separations of chromium from other members of the iron group by means of sodium carbonate and bromine, and was thereby led to investigate the action of these two reagents on solutions of nickel and cobalt salts.