348 PHYSIOLOGICAL CHEMISTRY 



ring will be formed. Observed in a strong light, this will be 

 seen to be of a flocculent character. 



48. Quantitative Estimation, (Approximate.) Pour the urine 

 into an Esbach tube up to the mark "urine" or U. Add Esbach's 

 reagent (2% citric acid, 1% picric acid) to the mark "reagent" 

 or R, close the tube carefully with a stopper and invert several 

 times until the fluids are well mixed. Allow the tube to stand 24 

 hours. Read on the scale the amount of the precipitate. The 

 scale corresponds to grams protein per 1000 c.c. of urine. 



Although this method gives only approximate results it 

 usually is sufficient for clinical purposes. 

 Serum Globulin Differentiation. 



49. Make a few cubic centimeters of clear urine alkaline with 

 ammonia. Filter off the precipitated phosphates. Neutralize 

 the filtrate with acetic acid and treat with an equal volume 

 of saturated ammonium sulphate solution. Globulin, if pres- 

 ent, will be thrown down. If the urine is rich in urates they 

 may be precipitated but may be recognized with the microscope 

 or by the murexid test. 



50. To a few cubic centimeters of clear urine, add an excess 

 of solid magnesium sulphate. Shake thoroughly and globu- 

 lins, if present, will be precipitated and will be. deposited above 

 the excess of salt. 



Add a few drops of clear urine to a large beaker full 

 of distilled water. If globulins are present, a white cloud will 

 appear. 



51. NUCLEOPROTEIN. 



After ascertaining that the clear urine does not coagulate 

 upon heating, dilute a small amount with water in equal quan- 

 tities, to prevent the precipitation of uric acid and to reduce 

 the solvent action of the salts upon the nucleoprotein. Add 

 acetic acid drop by drop. Nucleoprotein, if present, will be pre- 

 cipitated. 



Nucleoproteins often are present in large quantities in 

 various forms of proteinuria, such as physiologic proteinuria 



