In the manufacture of luminous paints commercial varnish containing lead or manganese must not be used, as it would destroy the luminosity of the paint. A suitable varnish is made by a process patented by Schatte, of Dresden. Three parts of molten Zanzibar or Kauri copal are dissolved in 12 parts of oil of turpentine; the solution is filtered and then mixed with 5 parts of pure linseed oil, which should have been heated and allowed to cool previous to mixing with the solution. It is this varnish that is referred to in all of the following recipes, and in all cases after mixing together the paint ingredients as specified below, they should be run through a paint mill. The latter should not contain iron rolls, as the particles of metal, liable to be detached, would affect the luminous properties of the paint. Blue: 42 parts of varnish. 10'2 parts of sulphate of barinm, 6'4 parts of ultramarine blue, 5.4 parts of cobalt blue, and 46 parts of luminous calcinm sulphide. Grey: 45 parts of varnish, 6 parts of barinm sulphate, 6 parts of calcinm carbonate, 0'5 part of ultramarine blue, and 6"5 parts of grey zinc sulphide. Green-. 48 parts of varnish, 10 parts of sulphate of barinm, 8 parts of green oxide of chrominm, and 34 parts of luminous sulphide of calcinm.

Orange: 46 parts of varnish, 175 parts of sulphate of barinm, 1 part of Indian yellow, 1.5 parts of madder lake, and 38 parts of luminous calcinm sulphide. Red: 60 parts of varnish, 8 parts of powdered sulphate of barinm, 2 parts of madder lake, 6 parts of realgar ired arsenic sulphide), and 30 parts of luminous calcinm sulphide. Violet: 12 parts of varnish, 10'2 parts of barinm sulphate, 2.8 parts of ultramarine violet, 9 parts of cobaltous arsenate, and 36 parts of luminous calcinm sulphide. Yellow- 48 parts of varnish, 10 parts of barinm sulphate, 8 parts of barinm chromate, and 31 parts of luminous calcinm sulphide. Yellowish brown: 18 parts of varnish, In parts of barinm sulphate, 8 parts of auri pigment, and 34 parts of luminous calcinm sulphide. White: 40 parts of varnish, 6 parts of barinm sulphate, 6 parts of calcinm carbonate, 12 parts of white zinc sulphide, and 36 parts of luminous calcinm sulphide.