As promised, here's the riveting conclusion to Making the Perfect Gin and Tonic...
Now that we've made wonderfully bubbly carbonated gin, it's time we make some tonic. Tonic water, originally developed to protect British troops from malaria while conquering strange and foreign lands, tasted awful in it's original formulation. The inclusion of quinine (from the bark of the South American cinchoa tree) made the beverage very bitter, but staved off malaria and allowed for the otherwise impossible colonization of Africa. Quickly the British colonialists realized that a dram full of booze helps the medicine go down and thus the famous G&T was born.
Modern tonic water bears little resemblance to the tonic water of the past, the quinine is still there but much reduced (and therefore less bitter), the sugar content is through the roof (~35g (!) of high fructose - about the same as any other soft drink on the market), and various flavors, preservatives, and citric acid (for a bit of tart). There are a few designer tonics out there now that use real sugar and less of it, but they're expensive, so lets make our own shall we?