The colorimetric determination of phosphorus

OF the several colorimetric methods for the determination of phosphorus which have been described during recent years, probably the Briggs 1922 modification of the Bell and Doisy 1920 method and the method of Fiske and Subbarow 1925 have met with most general favour. Both these methods depend on the reduction of phosphomolybdic acid to give a blue colour, the intensity of which is proportional to the concentration of phosphate.