Document o9nzD1LMb8k6pXa4mZ88ONLrR

PPIIGGMUEONTT f ^ f,r, r ^ * V Opaque white or colored powder used to nix with drying oils, varnish, etc. to supply the decorative function of paints, enamels, etc. The ansients used natural earth colors -- minerals, vegetable dyes, burnt bone, etc. as coloring pigments. Some of these were very good, a3 indicated by prehis toric cave pictures and the decorations .on muirmy cases. Modem chemists have developed colors much more brilliant, opaque, and per manent, possessing the highest degree of fineness and miscibility with vehicles. The principle white pigment is lead carbonate which has been used for cen turies, was first developed by the Old Dutch Process, whichwa3 patented in 1622. Others are lead sulphate, oxide and sulphide of zinc, titanium, end antimony oxide, and lithopone (a compound of zinc sulphide and barium sulphate). v. The chief blacks are lamp black (soot from incomplete combustion of oil), car bon black (from natural gas), charred bone or ivory blacks, graphite (natural or artificial). J Of the blues Prussian or Chinese blue, Ultramarine, and cobalt blue are most widely used. Phthalocyanine blue, an Ehglish discovery of a new type far surpassing any blue previously made. For yellow natural yellow ochre end precipitated yellow iron oxice are common, but lead or zinc chromate yellows supply most of the demand. The organic JfHansa51 yellows are very clean, strong, and permanent. Chrome green is a combination of Prussian blue and chrome yellow. Phthalo cyanine blue and "Hansa" Yellow ere used to produce a very permanent brilliant green. Chromium oxide is much used. Iron oxide and red lead are largely used as a protective coating over steel. Organic para and toluidine reds supply demand for brilliant permanent colors. OOOT-SWP-OO0007367