"The luminous mass consists of 4 parts potassium bichromate, 4 parts Gelatin, and 50 parts of calcium sulphide. The constituents are thoroughly dried and mixed by grinding. One part of the resulting power is stirred with 2 parts boiling water to a thickly fluid paint, 1 or 2 coats of which are applied with a brush to the paper or pasteboard to be made luminous. To avoid inequality in the thickness of the layer of paint the paper is passed through a sort of calender with rolls at a proper distnace to insure a uniform spreading of th luminous mass. The rolls may be heated if desired."