486 A MANUAL OF PHYSIOLOGY 



urine - picrate solution to equal 8 millimetres of the bichromate, 

 then the 10 c.c. of urine contains 10 x =g-o milligrammes of 



kreatinin. 



ii. Hippuric Acid. From horse's or cow's urine hippuric acid is 

 prepared by evaporating to a small bulk, and adding strong hydro- 

 chloric acid. The crystalline precipitate is washed with cold water, 

 then dissolved in hot water, and filtered hot. Hippuric acid separates 

 out from the filtrate in the cold in the form of long four-sided prisms 

 with pyramidal ends. Heated dry in a test-tube, the crystals melt, 

 and benzoic acid and oily drops of benzonitrile, a substance with a 

 smell like that of oil of bitter almonds, are formed. 



ABNORMAL SUBSTANCES IN URINE. 



12. Proteins (i) Qualitative Tests. (a) Boil and add a few drops 

 of nitric acid. A precipitate on boiling, increased or not affected 

 by the acid, shows the presence of coagulable proteins (serum- 

 albumin or globulin) . A precipitate of earthy phosphates sometimes 

 forms on boiling. It is distinguished from a precipitate of proteins 

 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 or 

 globulin. If much albumose is present, a white precipitate, which 

 disappears on heating, may be formed. When this test is performed 

 with undiluted urine, uric acid may be precipitated and cause a 

 brown colour at the junction. A similar ring may be found in the 

 absence of proteins when the test is made on the urine of a patient 

 who has been taking copaiba. In very concentrated urine a white 

 ring of nitrate of urea may be formed. A coloured ring is frequently 

 seen, owing to the oxidation of certain chromogens of urine. 



(c) Filter some urine, and add to the filtrate 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 proteins. 



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

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

 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 (Albumosuria) . Coagulable proteins 

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

 ing 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 (proteoses) are present. A slight precipitate might pos- 

 sibly be due to the formation of ammonium urate. A further test 

 may be performed on the original urine if it is free from coagulable 

 proteins, or on the filtrate after their removal. Add a drop or two 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. 



