URINE 301 



test, since prolonged action of nitric acid will separate cell- 

 proteins, which may be present. 



When urea is present in large quantities, particularly if 

 the volume of the urine is low, crystals of urea nitrate may 

 be deposited at the line of contact of the two liquids. The 

 crystalline character of this material suffices for differentiation. 



In the presence of large quantities of uric acid, a whitish 

 ring may appear several mm. above the line of contact. If 

 doubt exists as to either of these two conditions, dilute the urine 

 and repeat the test. If the ring was due to uric acid or urea, it 

 will fail to appear after dilution. A cloud, high up in the urine, 

 may be caused by mucin. The pigments form rings of dark 

 color between the urine and the acid. These rings, once recog- 

 nized, cannot be mistaken for proteins. A ring due to certain 

 ingested substances, e. g., copaiba, may be dissolved with ether; 

 iodine, excreted in the urine, forms a dark ring at the surface 

 of the nitric acid. Indican is the most common pigment produc- 

 tive of colored rings. 



3. Ferrocyanide Test. Add a few drops of potassium ferrocy- 

 anide solution to the clear urine and then acidify with acetic acid. 

 In the presence of albumin or globulin, a white cloud or ring 

 will be formed. Observed in a strong light, this will be seen to 

 be of a flocculent character. 



4. 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 E, close the tube carefully with a stopper and invert several 

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

 hours. Eead 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. 



5. Serum Globulin Differentiation. 



(a) 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 



