URINE 303 



a. PROTEOSES AND PEPTONES. 



These forms may appear in the urine occasionally. 



1. Neutralize and boil the clear urine to remove coagulable 

 proteins. Filter and to the filtrate, slightly warm, add a few 

 drops of potassium ferrocyanide solution and 10% acetic acid. 

 If a precipitate appears, it is proteose. Heat and it will dis- 

 appear; cool and it will reappear. 



2. To clear urine, previously acidified and boiled, add ex- 

 cess of solid ammonium sulphate and a few drops of acetic 

 acid; proteoses, if present, will be precipitated. Filter. Dis- 

 solve the precipitate in distilled water and apply the biuret 

 test. Ammonium sulphate interferes with the reaction and 

 must be removed with barium carbonate. 



3. A specimen of urine may be dialyzed and the diffusate 

 tested for peptones with the biuret test. 



II. Carbohydrates. 



The carbohydrates most frequently found in the urine are 

 dextrose and lactose. In addition to these, pentoses, levulose, 

 galactose, and saccharose may occur. These substances are 

 detected by the usual reduction, phenylhydrazine and fermen- 

 tation tests, or by the optical activity of the urine containing 

 them. For differentiating among the various carbohydrates, 

 the methods employed are those already familiar to the student 

 from his study of the carbohydrates. 



With samples of the carbohydrate urine furnished perform 

 the following tests: 



a. REDUCTION TESTS. Albumin or globulin must be removed 

 if present by acidifying slightly with acetic acid, boiling and 

 filtering. 



1. Qualitative Test. Perform the Fehling test. The test is 

 subject to two sources of error : unless the liquid is boiled the test 

 is not sensitive; if boiled, other substances such as uric acid, 

 creatinine, mucin, pentoses, glycuronic acids, lactose, or a reduc- 

 ing agent used in the preservation of the urine, su,ch as chloro- 

 form or formaldehyde may give a reduction. 



