This section is from the book "Chromatography; Or, A Treatise On Colours And Pigments, And Of Their Powers In Painting", by George Field. Also available from Amazon: Chromatography, or A Treatise on Colours and Pigments, and of Their Powers in Painting.
Orange being a colour compounded of red and yellow, the place of original orange pigments may be supplied by mixture of the two latter colours; by glazing one over the other; by stippling, or other modes of breaking and intermixing them in working, according to the nature of the work and the effect required. For reasons before given, mixed pigments are inferior to the simple or homogeneous in colour, working, and other properties: yet some pigments mix and combine more cordially, and with better results, than others; this is the case with the liquid rubiate and gamboge, and they form the best and most durable mixed orange of all hues for painting in water. In oil the compounding of colours is more easily effected.