Orthophosphoric acid

Metaphosphoric acid gives a white precipitate with nitrate of silver solution; orthophosphoric acid does not give any, save on the addition of an alkali, and the precipitate then produced is yellow.

Evaporate 25 cc. of orthophosphoric acid solution to dryness, setting the burner beneath the dish and adjusting the flame so that the tip does not quite touch the dish.

With the exception of the fertilizer products, most phosphorus compounds are derived from orthophosphoric acid, produced by the oxidation of elemental phosphorus.