PRACTICAL EXERCISES 429 



(serum-albumin or globulin). A precipitate of earthy phosphates 

 sometimes forms on boiling. It is distinguished from a precipitate 

 of proteids by dissolving on the addition of acid. 



(b) Heller's Test. Put some nitric acid in a test-tube. Pour 

 carefully on to the surface of the acid a little urine. A white ring at 

 the junction of the liquids indicates the presence of albumin, globulin 

 (or albumose?). When this test is performed with undiluted urine, 

 uric acid may be precipitated and cause a brown colour at the junc- 

 tion. A similar ring may be found in the absence of proteids when 

 the test is made on the urine of a patient who has been taking 

 copaiba. 



(<r) Filter some urine, and add to the nitrate its own volume of 

 acetic acid. A precipitate may indicate mucin or nucleo-albumin. 

 If any is formed, filter it off, and add to the filtrate a few drops of 

 potassium ferrocyanide. A white precipitate shows the presence of 

 proteids. 



(d) Test for Globulin in Urine. Serum-globulin probably never 

 occurs in urine apart from serum-albumin. It may be detected by 

 Kauder's test. Make the urine alkaline with ammonia, let it stand 

 for an hour and filter. Half saturate the filtrate with ammonium 

 sulphate, i.e., add to it an equal volume of a saturated solution of 

 ammonium sulphate. Serum-globulin is precipitated, serum-albumin 

 is not. 



(e) Test for Albumose in Urine(Albumosurid). Coagulable proteids 

 are removed by boiling the urine (acidulated if necessary), and filtering 

 off the precipitate if any. The filtrate is neutralized. If a further 

 precipitate falls down it is filtered off, the clear filtrate is heated in a 

 beaker placed in a boiling water-bath, and there saturated with crystals 

 of ammonium sulphate. A precipitate indicates that albumoses (pro- 

 teoses) are present. A slight precipitate might possibly be due to the 

 formation of ammonium urate. A further test may be performed on 

 the original urine if it is free from coagulable proteids, or on the 

 filtrate after their removal. Add a few drops of pure nitric acid. If 

 albumoses are present, a precipitate is thrown down which disappears on 

 heating, and reappears on cooling the test-tube at the cold-water tap. 



(/) Test for Peptone in Urine (Peptonurid). Place some of the 

 urine in a beaker on a boiling water-bath for thirty minutes, and 

 saturate with ammonium sulphate crystals. Then boil over a small 

 flame or in an air-bath for half an hour. All the proteids, including 

 peptones, are precipitated. But the peptones can still be redissolved 

 by water, the others not. Filter hot. Wash the precipitate on the 

 filter with a boiling saturated solution of ammonium sulphate. Then 

 extract the residue with cold water, filter, and test the nitrate by the 

 biuret test (addition of very dilute cupric sulphate and excess of 

 sodium hydrate). A rose colour indicates the presence of peptone 

 (P- 379) (S)), but if the reaction is only a faint one, it may be due to 

 urobilin (Stokvis). 



(2) Quantitative Estimation of Coagulable Proteids (Serum- 

 Albumin and Globulin} (a) Gravimetric Method. Heat 50 to 100 

 c.c. of the urine to boiling, adding a dilute solution (2 per cent.) of 



