Orthophosphoric acid is a versatile solvent for diverse materials and the resulting solutions may be analyzed polarographically. The polarographic behavior of several elements in a M phosphoric acid base solution has therefore been investigated, and half-wave potentials and diffusion-current constants are reported. With use of the square-wave polarograph, simple and direct procedures are described for thc determination of small amounts of lead in copper, tin, zinc and aluminum-base alloys, respectively. The determination of lead (a few tenths of a per cent) in monazite and in various miscellaneous materials is also described. With no samples were chemical separations necessary after their dissolution in phosphoric acid. Direct procedures are also described for the determination of the copper content of lead, tin, and aluminum-base alloys, the zinc content of copper, tin, and aluminum-base alloys, and the cadmium content of tin and lead-base alloys. All the procedures outlined provide a considerable improvement on those in which use is made of conventional polarography. (auth) with a mean recovery of 100.3% and a standard devia