The use of ingested sodium benzoate as a test for renal function was first described by Swanson and me, in a preliminary report before the Federation of American Societies for Experimental Biology, in December, 1920. The full report was published in August, 1921.1 In June, 1921, Snapper2 published a report of work along similar lines. He found that after ingesting 5 gm. of sodium benzoate, the normal person on a porridge diet eliminated about 75 per cent. of it in the form of hippuric acid in the course of six hours. Lewis3 had previously found a much more rapid elimination of hippuric acid under similar conditions, and this was verified by Kingsbury and Swanson. For this reason, it is believed that Snapper did not obtain all the hippuric acid eliminated in the test specimens of urine, and that these low results were due to the failure of his analytic method.