Phosphates

Phosphates are a class of soft drink flavored with phosphoric acid, which imparts a distinct but flat sourness. Chemists use various methods to produce phosphoric acid, also called acid phosphate, from phosphorus or phosphate rocks.

Phosphates first appeared in the late 1870s as the result of a patent medicine craze. Companies promoting the healing properties of nostrums like Horsford’s Acid Phosphate discovered that consumers liked the powder’s sour taste, particularly when mixed with sugar and water. Somebody tried adding it to a fruit syrup soda drink, and the phosphate quickly made the leap from the drugstore’s medicine counter to its soda fountain. The chemical was usually added to the soda in the form of a solution of acid phosphate mixed with water.