The term cherry phosphate has a lovely, faded, elegiac ring to it. It brings to mind an ornate soda fountain, a white-jacketed soda jerk, and a precocious child clambering up a stool to a marble countertop, squawking, “Hey, mister, gimme a phosphate!” And is that the tinkly sound of a player piano? A cherry phosphate has always seemed wonderfully Capra-esque to me, even though I had no idea what was in it.
Neither, it turns out, did Darcy O’Neil, a chemist and bartender with an interest in historic drink. Someone asked him a few years ago what he knew about antique soft drinks. Not much, he realized. So he started digging through old texts and handbooks. In the process, he discovered the surprisingly complex ecosystem of the early soda fountain—which involved some curious ingredients (strychnine, tincture of oats, Leroy’s Vomito-Purgative Elixir) and wasn’t always imbued with a cherry-on-top innocence (Los Angeles Times, 1902: “They Thirst for Cocaine: Soda Fountain Fiends Multiplying. Slaves to the ‘Coca Cola’ Habit”).
O’Neil recently published his research and a slew of drink recipes in an intriguing little book called Fix the Pumps. Among the more fascinating long-forgotten fountain ingredients he examines is acid phosphate, a souring agent both cheaper and less perishable than lemon or lime juice. It consists of neutralized phosphoric acid and mineral salts, O’Neil told me. That may not sound like much of a marketing slogan, but it’s a great improvement over 19th-century advertisements for best-selling Horsford’s Acid Phosphate, which boasted: “It is not nauseous, but agreeable to the taste.”