PRACTICAL EXERCISES 5I? 



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. 

 Ssrum-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 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 

 (proteoses) 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 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. 



(2) Quantitative Estimation of Coagulable Proteins (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 acetic acid by 

 drops as long as the precipitate seems to be increased. Filter through 

 a weighed filter. Wash the precipitate on the filter with hot water, 

 then with hot alcohol, and finally with ether. Dry in an air-bath at 

 110 C., and weigh between watch-glasses of known weight. 



(b) Esbach's Method. Esbach's reagent is made by dissolving 

 10 grammes of picric acid and 20 grammes of citric acid in boiling 

 water (800 or 900 c.c.), and then making up the volume to a litre. The 

 so-called albuminimeter is simply a strong glass tube graduated and 

 marked in a certain way. Fill the tube up to the mark U with the 

 urine. Then add the reagent up to the mark R. Close the tube with 

 the rubber cork, and invert it a dozen times without shaking. Set the 

 tube aside for twenty-four hours, then read off the graduation on the 

 tube which corresponds with the top of the precipitate. The figures 

 indicate the number of grammes of dry protein in a litre of the urine. 

 Suppose the top of the sediment is at 4, this will indicate 4 grammes per 

 litre, or 0*4 per cent. The method is of some clinical importance, owing 

 to its simplicity, although it is, of course, not very accurate. 



14. Sugar (i) Qualitative Tests (a) Trommer's Test (p. 10). It is to 

 be remarked that some substances present in small amount in normal 

 urine reduce cupric sulphate e.g., uric 'acid (present as urates) and 

 kreatinin but although a normal urine may thus decolourize the 

 copper solution, it rarely causes so much reduction that a yellow or red 

 precipitate is formed, as is the case in diabetic urine. Glycuronic acid 

 (p. 476) also reduces cupric salts, as does alcapton or homogentisinic 

 acid, a substance found in rare cases in disease (p. 477). 



(b) Fehling's Test. Fehling's solution (p. 518) is brought to the boil ill 

 a test-tube, a little of the urine then added, and the change of colour 

 noted. Benedict's modification of Fehling's solution may also be used. 

 It has the. advantage that it keeps indefinitely, and therefore is always 

 ready for use, and is also said to be more delicate. 



(c) Phenyl-Hydrazine Test. This test depends upon the fact that 

 phenyl-hydrazine forms with sugars such as glucose (dextrose), maltose, 

 isomaltose, etc., but not with cane-sugar, characteristic crystalline 

 substances (phenyl-glucosazone, phenyl-maltosazone, etc.) which can 



