The Ghost Map: The Story of London's Most Terrifying Epidemic--and How It Changed Science, Cities, and the Modern World

by Steven Johnson

Brewed tea possesses several crucial antibacterial properties that help ward off waterborne diseases: the tannic acid released in the steeping process kills off those bacteria that haven’t already perished during the boiling of the water. The explosion of tea drinking in the late 1700s was, from the bacteria’s point of view, a microbial holocaust. Physicians observed a dramatic drop in dysentery and child mortality during the period. (The antiseptic agents in tea could be passed on to infants through breast milk.) Largely freed from waterborne disease agents, the tea-drinking population began to swell in number, ultimately supplying a larger labor pool to the emerging factory towns, and to the great sprawling monster of London itself.