acid phosphate was a compound created in 1868 by Professor Eben Norton Horsford (1818–1893) of Cambridge, Massachusetts, as a tonic for dyspepsia, nervousness, and seasickness and an ingredient for various culinary uses. Made originally by treating bone ash with sulfuric acid, which yielded a mixture of phosphoric acid and subsidiary phosphate salts of calcium, magnesium, potassium, and sodium, it first found a use in food as a substitute for vinegar but was quickly adopted by soda fountains as a shelf-stable substitute for lemons and limes, to which it had a similar level of acidity (around pH 2.0).
Acid phosphate solution became popular because it was shelf-stable in a time when refrigeration or rapid shipping of citrus fruit was not practical. Its popularity continued with pharmacists in the nineteenth century because citric acid powders were often made by evaporating lemon and lime juice in tin pans, which contained lead, and it was safe from the possibility of such contamination. See citric acid.
Acid phosphate has pure sour flavor with a unique flavor-enhancing effect from the dissolved mineral salts. It was often described as adding a “sparkle” to soda drinks because it can produce a subtle tingling sensation on the tongue.
Though acid phosphate was immensely popular at soda fountains, it found sparse use in cocktail bars, with rare exceptions such as the Angostura Phosphate, a hangover remedy offered at some bars, and the Montauk Riding Club Cocktail published in the Waldorf Astoria Bar Book in 1934, with brandy, Calisaya, and gum syrup. See Waldorf Astoria. Modern bartenders have taken a more accepting approach to incorporating acid phosphate in cocktails as a replacement for citrus juice, although its use is still rather uncommon.
Recipe (Angostura Phosphate): Place in short highball glass: 3 ml acid phosphate, 5 ml Angostura bitters, and 30 ml lemon syrup. Fill with chilled sparkling water. Some modern drinkers prefer this with ice added to the glass.
Crockett, Albert Stevens. Waldorf Astoria Bar Book. New York: Aventine, 1934.
Hiss, Emil. Standard Manual of Soda and Other Beverages. Chicago: G. P. Engelhardt,1897.
O’Neil, Darcy. Fix the Pumps. N.p.: Art of Drink, 2009.
By: Darcy O’Neil