EXAMINATION OF THE URINE. 125 



II. Detection of Sulphates. 



Add some hydrochloric acid to the urine and then a little 

 barium chloride solution: white precipitate of barium sul- 

 phate, BaS0 4 (normal conduct), or only a faint turbidity 

 (after the use or absorption of considerable carbolic acid). 



III. Detection of Ethereal Sulphates. 



Mix 20 cc. of the urine and 20 cc. of the alkaline barium 

 chloride solution (see page 124) and filter. Boil the filtrate 

 with fuming hydrochloric acid (one-half volume): turbidity 

 due to the precipitation of barium sulphate, which is ordi- 

 narily slight, but if the amount of ethereal sulphates is 

 abnormally large (from different causes) it may be consider- 

 able. 



IV. Detection of Phosphates. 



(a) In general. About 20 cc. of urine are treated with 

 acetic acid and uranyl acetate solution: yellowish-white 

 precipitate of uranium phosphate or uranyl phosphate 

 (U0 2 )HP0 4 . 



(b) Separate Detection of Phosphoric Acid united to the 

 Alkali Metals and to the Alkali-earth Metals. Make 50 cc. 

 of urine alkaline with ammonia and after the mixture has 

 stood for some time filter from the precipitate of alkali- 

 earth phosphates. The filtrate contains the phosphoric acid 

 combined with the alkali metals, as may be shown by the 

 addition of acetic acid and uranyl acetate solution. Dissolve 

 the precipitate, after it has been thoroughly washed with 

 water, by pouring on acetic acid; phosphoric acid may also 

 be shown to be present in this solution by means of the uranyl 

 acetate solution. 



V. Detection of Ammonium Salts. 



Put 25 cc. of the urine, a few drops of thymol solution, and 

 about 25 cc. of milk of lime in the Schlosing apparatus (an 



