A method is proposed for the determination of organic phosphorus in sea water; in this procedure the organic material is oxidized with perchloric acid and the organic phosphorus is converted to phosphate. Oxidation in a perchloric acid medium ia superior to sulfuric acid: (a) The perchlorate salts formed upon digestion of sea water are readily water-soluble in contrast to certain sulfates; (b) A small blank correction for impurities must be applied....