8 INFLUENCE OF BORAX AND 



formed was distilled into quarter-normal hydrochloric acid, the 

 latter being titrated with quarter-normal ammonia, using 

 congo red as an indicator. 



Sulphur and phosphorus were determined in the customary 

 manner by evaporating a given volume of the urine 25 c.c. 

 for each determination in a roomy silver crucible with 10 

 grams of pure sodium hydroxide (made from the metal) and 2 

 grams of potassium nitrate, igniting the residue until oxidation 

 was complete and treating the fused mass with water. For 

 sulphur, the mixture was acidified with hydrochloric acid, 

 evaporated to dryness, the residue moistened with a few drops 

 of hydrochloric acid and dissolved in hot water. The filtered 

 solution was then precipitated in the usual manner with 

 barium chloride, the resultant barium sulphate filtered, ignited, 

 and weighed, thus giving data for calculation of the total 

 sulphur. For phosphorus, the aqueous extract of the oxidized 

 urine was acidified with nitric acid, evaporated to dryness, the 

 residue moistened with nitric acid and dissolved in warm 

 water. From this solution the phosphoric acid was precipi- 

 tated in the usual manner with molybdic solution and eventually 

 transformed into ammonio-magnesium phosphate. From the 

 weight of magnesium pyrophosphate obtained, the total 

 phosphorus of the urine was calculated. 



Uric acid was determined by the well-known Salkowski- 

 Ludwig silver method, using 100-200 c.c. of urine. 



Phosphoric acid was determined by Mercier's * modification 

 of Neubauer's method, i. ., by titration of 50 c.c. of urine with 

 a standard solution of uranium nitrate and tincture of cochineal 

 as an indicator. 



Total sulphuric acid was estimated by diluting 25 c. c. of 

 urine with 3-4 volumes of water, adding 5 c. c. of dilute 

 hydrochloric acid, heating to boiling, and precipitating hot 

 with barium chloride. The barium sulphate so obtained, after 

 standing twenty-four hours in a warm place, was washed with 

 hot water until free from chlorides and lastly with hot alcohol, 

 ignited, and weighed. 



* See Neubauer und Vogel's Analyse des Hams, neunte Auflage, p. 450. 



