Brewster married a second time in Nice, on 26 (or 27) March 1857, to Jane Kirk Purnell (b. 1827), the second daughter of Thomas Purnell of Scarborough. Lady Brewster famously fainted at the Oxford evolution debate of 30 June 1860. Brewster died in 1868, and was buried at Melrose Abbey, next to his first wife and second son. The physics building at Heriot-Watt University is named in his honour.