Like carbonated soda, that other fountain shop staple, the milk shake, in its early forms, was once more a tonic than a treat, Ried explains. During the Victorian era, restorative milk drinks—such as koumyss, a Mongolian fermented milk beverage—were all the rage at fashionable spas in England and America, and eventually drugstores started serving "healthful" blends of milk, shaved ice, and, often, whiskey. Indeed, in an old primer for druggists published in 1897 called The Standard Manual of Soda and Other Beverages, given to me by a friend who knew of my love of shakes, I found recipes for milk shakes fortified with everything from eggs to Angostura bitters. Eventually, alcohol fell out of favor, and the Prohibition-fueled demand for soft drinks inspired a burst of inventiveness among soda jerks: pharmacies jockeyed to coin signature drinks and to install the latest gadgets, most notably the Hamilton Beach Drinkmaster, an appliance equipped with a blending stick and removable cup that made it easy for operators to mix shakes to their desired thickness. (Ray Kroc, the father of the McDonald's restaurant franchise, got his start as a salesman of milk shake machines.) As Ried points out, the aeration caused by mechanical mixing gave shakes a creamier texture, and by the 1920s, many shops were gilding the lily by replacing shaved ice with another popular treat: ice cream.