CHAPTER X 

 URINE 



Qualitative Study 



For the qualitative study of urine each student will need 2 

 liters of urine. (3 liters, if purine bases are to be included.) 

 The urine should be preserved by the addition of a 5% solution 

 of thymol in chloroform, about 5 c.c. per liter of urine. This 

 preservative should be placed in the flask before the urine is col- 

 lected, as otherwise the urine may decompose. 



Inorganic Constituents. 



1. CHLORIDES. Acidify about 10 c.c. of urine with 2-3 drops 

 cone, nitric acid and add a drop of silver nitrate. If chlorides 

 are present in normal quantity, a solid clump of silver chloride 

 will sink to the bottom. If but small amounts of chlorides are 

 present, the urine becomes only cloudy. If an attempt be made 

 to confirm chlorides by dissolving the precipitate in ammonia, a 

 heavy flocculent precipitate of earthy phosphate will be thrown 

 down. Such a precipitate might be filtered off however, and the 

 dissolved chlorides reprecipitated by adding nitric acid. 



PHOSPHATES. There are two general classes of phosphates 

 in urine, alkali, i.e., sodium and potassium, and earthy, i.e., 

 calcium and magnesium. These phosphates are present both as 

 mono- and di-hydrogen salts, e.g., Na 2 HP0 4 and NaH 2 P0 4 . There 

 also is phosphorus in urine which is not detected in the usual 

 precipitation tests. It is in organic combination and may be 

 detected only after fusion with an oxidizing agent. 



2. Earthy Phosphates. To about 10 c.c. urine, add ammonia 

 to alkalinity and warm. A flocculent precipitate is earthy phos- 

 phates. The alkali phosphates remain in solution. 



3. Filter off the precipitated earthy phosphates and add 



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