Tonic water contains quinine, which is a common (although not recommended first-line anymore) treatment and preventative for malaria. Gin and tonic was invented by the British in colonial tropics to fight malaria (quinine was isolated from a bark; the gin was added to make it taste better!). Here's an informative article about the anti-malarial history of gin and tonic: http://www.slate.com/articles/health_and_science/foreigners/2013/08/gin_and_tonic_kept_the_british_empire_healthy_the_drink_s_quinine_powder.html
I knew that drinks with quinine like Tonic Water and Bitter Lemon were used to treat Malaria but I had no idea they especially invented Gin and Tonic for that. That Tonic is or was different from the one most of us may know though. The quinine levels are way low in the commercially available drinks.
give the guy a break this was #5 of a series, he was hardly sitting on his thumbs, as well as doing god-knows how many other quizzes, AND checking and updating them
Of course Bach wrote for lots of solo instruments: his greatest works for solo instrument were probably the Goldberg Variations, written for the harpsichord, the Well-Tempered Clavier (which could be played on an organ as well) and his Cello Suites.