Some twenty-five or thirty years ago a white pigment was offered to paint makers under the name of zinc lead, made from a lead and zinc ore found in Colorado and then known as Colorado zinc lead. It was a combination which the chemists found to consist of about 28 per cent. lead sulphate and 72 per cent. zinc oxide, rather coarse in structure and with decided yellowish cast. Many paint grinders experimented with this pigment and finally adopted it as a base for ready-mixed paints, while others made it the basis for a line of cheap tinted paste paints, sold as building paints and paints for agricultural implement makers, because of its comparatively low price, as compared with white lead and domestic zinc oxides. These pastes were, however, rarely sold pure, but the pigment was mixed with other inert mineral bases, such as calcium carbonate (whiting), calcium sulphate (gypsum), barium sulphate (barytes) or kaolin (China clay) or magnesium silicate (asbestine). A flood of these paste paints was let loose upon the market, especially by Western firms, under fanciful names or brands, and because of the low prices, their sale was enormous for a time. But the inevitable reaction set in later on, and, in spite of the improvement made in further developments of the pigment. when it was made of a much purer white and of a composition consisting of about 45 to 48 per cent lead sulphate and 52 per cent zinc oxide, it has lost ground and is rarely heard of today.