CURRENT RECIPE: use 10 grams of tannin, 150 grams of glycerin, and 43mL of 85% phosphoric acid. And if you use Durkee caramel color (since Shanks no longer seems to be available), use 185mL instead of 320mL, since it's much stronger.
PER LITER OF SODA (VERSION 111C): 104 grams sugar (dissolved in a minimum volume of water) 1mL flavor solution A (alcohol-based) 10mL flavor solution B (water-based) Top off to 1 liter with cold carbonated water
FLAVOR SOLUTION A: dilute 20mL of the following oil mixture to a volume of 1 liter using food-grade 95% alcohol. 45.8mL lemon oil 36.5mL lime oil 8mL tea tree oil (from Australian tea tree, Melaleuca Alternifolia) 4.5mL cassia cinnamon oil 2.7mL nutmeg oil 1.2mL orange oil (regular sweet orange) 0.7mL coriander oil 0.6mL fenchol (any version of alpha-fenchol should work)
FLAVOR SOLUTION B: dilute the following mixture to a volume of 1 liter using water. 185mL Durkee caramel color 150 grams food-grade vegetable glycerin 43mL 85% phosphoric acid 10 grams wine tannin 9.65 grams caffeine 10mL 5% vinegar 10mL vanilla extract (or a solution containing 0.95 grams per liter of vanillin)