Engraving by J Pas showing the 'Common Colour Mill' (1); 'Rawlinson's Colour Mill' (2); the 'Improved Indigo Mill' (3-4); and 'Apparatus for the protection of Colour Grinders' (5). Rawlinson's hand-operated mill, developed in 1804, was faster and more economical than earlier mills (top right). The colour grinder (bottom centre) is being protected from inhalation of the toxic pigments he is grinding; the fumes and loose particles of pigment are drawn away from the grinding slab by heat from a furnace at the other end of the pipe and hood. The pigments produced were used for paint and other artists' materials. Illustration from 'Encyclopaedia Londinensis, or, Universal Dictionary of Arts, Sciences, and Literature' published in London, 1810-1829.
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