Producing indigo dye with slave labour: West Indies or Central America, 1725. Artist: Anon

Producing indigo dye with slave labour: West Indies or Central America, 1725. Indigo tinctoria is cut, tied in bundles, steeped in water and fermented in the centre tank. The liquor is drawn off into the bottom tank where it is agitated. The indigo separates out and is allowed to settle and the tank is drained. The residue is removed and put in cases to dry, left. From A Compleat History of Drugs by P Pomet, (London, 1725). First published in French (Paris, 1725). (Photo by Oxford Science Archive/Print Collector/Getty Images)