Acid Phosphate was created in 1868 as an invigorating health tonic, pretty much like every other patent medicine created during the period. However, unlike many of the “magic tonics”, Acid Phosphate was actually useful and became a key ingredient in soda drinks because of its pleasant acidity.
Prior to mass transportation and refrigeration, ingredients like lemons and limes were hard to come by outside the southern states and port cities like New York. To compensate, soda fountain operators would purchase lemon oil, which was shelf stable and mix it with Acid Phosphate and soda to create the immensely popular lemon soda. Acid Phosphate also enhanced the flavour of drinks because it included a small quantity of various salts (potassium, calcium and magnesium).