A simple method of making pure chrome green

Manufacturer and builder 7, 1875

Common chrome green is made by mixing chrome yellow with a little Prussian blue; it is by no means so good a color as the pure chrome green which is the sesqui-oxid of chromium Cr₂O₂.

A new, simple, and cheap way to make the latter compound from the potassium bichromate, is to mix it with three times its weight of burnt gypsum or plaster of Paris, and made it thoroughly red-hot; then the sulphuric acid of the gypsum will combine with the potassium, and form the soluble potassium sulphate, while the lime becomes quicklime; after cooling the latter is dissolved out with diluted hydrochloric acid, and the potassium sulphate with water. The remaining powder is a pure chrome green, not only adapted for water-colors, oil-paints, and printing-ink for greenbacks, but even for a dye on textile fabrics.