Last month FARM CHEMICALS presented aquot;What Polyphosphates Are, aquot; first article in this exclusive four part series written ... TV A seeks other ways of minimizing the magnesium problem. ... 9, 10a#39; Acid containing about 54% P^Os is ammoniated in a two-stage reaction system. ... Supplemental ammonia and water are added to maintain the desired grade. ... Davis, C. H., Lee, R. G. Pilot-plant studies of the direct production of ammonium polyphosphate from wet- process phosphoric acid.