Phosphate

Acid phosphate, syrup, and sparkling water — the 1870s soda fountain staple, Prohibition making it the sophisticated adult drink when bars closed from 1920 to 1933.

The phosphate is one of the oldest and most distinctly American non-alcoholic drinks, born in the soda fountain culture that flourished from the 1870s onward and reached its peak during the Prohibition era. The key ingredient is acid phosphate — a diluted phosphoric acid solution developed specifically for soda fountains in the 1870s — which added a clean, tart bite that made the drinks both refreshing and more complex than plain sweetened soda water. Pharmacist Charles Aldrich is often credited with popularizing acid phosphate as a soda ingredient in the 1870s, and the resulting phosphate drinks became a staple of drugstore soda fountains across the United States. A basic phosphate was simply carbonated water, acid phosphate, and flavoring syrup — typically fruit or cream — but skilled soda jerks developed hundreds of variations. The soda fountain's importance in American social life expanded dramatically during Prohibition from 1920 to 1933, when alcohol was banned and bars were shuttered. Soda fountains became the de facto gathering places for adults seeking sophisticated, complex beverages, and the phosphate — with its genuine tartness and depth — became the choice of those who wanted something more interesting than sweet soda. After Prohibition ended, soda fountains gradually declined as bars returned, and acid phosphate faded from mainstream availability. It experienced a revival beginning in the 2000s when craft soda and historical cocktail researchers began sourcing and reintroducing the ingredient.