Bulk-percentage | Percentage | Gr. Per Oz. of H(UO_{2})PO_{4}. | P_{2}O_{5}. | P_{2}O_{5}. --------------------+-------------+------------ ½ | 0.02 | 0.1 1 | 0.04 | 0.19 1½ | 0.045 | 0.22 2 | 0.05 | 0.24 2½ | 0.055 | 0.26 3 | 0.06 | 0.29 3½ | 0.065 | 0.31 4 | 0.07 | 0.34 4½ | 0.075 | 0.36 5 | 0.08 | 0.38 6 | 0.09 | 0.43 7 | 0.1 | 0.48 8 | 0.11 | 0.53 9 | 0.12 | 0.58 10 | 0.13 | 0.62 11 | 0.14 | 0.67 12 | 0.15 | 0.72 13 | 0.16 | 0.77 14 | 0.17 | 0.82 15 | 0.18 | 0.86 16 | 0.19 | 0.91 17 | 0.2 | 0.96 18 | 0.21 | 1.0 19 | 0.22 | 1.06 20 | 0.23 | 1.1 21 | 0.24 | 1.15 22 | 0.25 | 1.2 23 | 0.26 | 1.25 24 | 0.27 | 1.3 25 | 0.28 | 1.35 --------------------+-------------+------------ Bulk-percentage to be read from graduation on the side of the tube. Purdy's Centrifugal Method.--Take 10 c.c. urine in the graduated tube, add 2 c.c. of 50 per cent. acetic acid, and 3 c.c. of 5 per cent. uranium nitrate solution. Mix; let stand a few minutes, and revolve for three minutes at 1200 revolutions. {62} The bulk of precipitate is normally about 8 per cent. The percentage of phosphoric acid by weight is, roughly, one-eighty-fifth of the bulk-percentage. * * * * * 3. Sulphates.--The urinary sulphates are derived partly from the food, especially meats, and partly from body metabolism. The normal output of sulphuric acid is about 1.5 to 3 gm. daily. Quantitative estimation of the total sulphates yields little of clinical value. * * * * * Purdy's Centrifugal Method.--Take 10 c.c. urine in the graduated tube and add barium chlorid solution to the 15 c.c. mark. This consists of barium chlorid, 4 parts; strong hydrochloric acid, 1 part; and distilled water, 16 parts. Mix; let stand a few minutes, and revolve for three minutes at 1200 revolutions a minute. The normal bulk of precipitate is about 0.8 per cent. The percentage by weight of sulphuric acid is about one-fourth of the bulk-percentage. TABLE FOR THE ESTIMATION OF SULPHATES AFTER CENTRIFUGATION