URINE 441 



cline the tube and, by means of a pipette, allow 5 c.c. of urine, acidified with acetic 

 acid, to flow slowly down the side. *A white zone will form at the point of contact. 

 This is an exceedingly delicate test, in fact too delicate for ordinary clinical purposes, 

 since it serves to detect albumin when present in the merest trace (1:250,000) and 

 hence most normal urines will give a positive reaction for albumin when this test is 

 applied. Proteose and peptone are also said to respond to this test. 



4. Coagulation or Boiling Test. (a) Heat 5 c.c. of urine to boiling in a test- 

 tube. (If the urine is not clear it should be filtered.) A precipitate forming at 

 this point is due either to albumin or to phosphates. Acidify the urine slightly 

 by the addition of 3-5 drops of very dilute acetic acid, adding the acid drop by 

 drop to the hot solution. If the precipitate is due to phosphates it will disappear 

 under these conditions, whereas if it is due to albumin it will not only fail to 

 disappear but will become more flocculent in character, since the reaction of a 

 fluid must be acid to secure the complete precipitation of the albumin by this 

 coagulation process. 



Too much acid should be avoided since it will cause the albumin to 

 go into solution. Certain resin acids may be precipitated by the 

 acid, but the precipitate due to this cause may be easily differentiated 

 from the albumin precipitate by reason of its solubility in alcohol. 



(b) A modification of this test in quite general use is as follows : Fill a test- 

 tube two-thirds full of urine and gentry heat the upper half of the fluid to boiling, 

 being careful that this fluid does not mix with the lower hah*. A turbidity indi- 

 cates albumin or phosphates. Acidify the urine slightly by the addition of 3-5 

 drops of dilute acetic acid, when the turbidity, if due to phosphates, will disappear. 



Nitric acid is often used in place of acetic acid in these tests. In 

 case nitric acid is used ordinarily 1-2 drops is sufficient. 



5. Acetic Acid and Potassium Ferrocyanide Test. To 5 c.c. of urine in a 

 test-tube add 5-10 drops of acetic acid. Mix well and add potassium ferro- 

 cyanide drop by drop, until a precipitate forms. 



This is a very delicate test. Schmiedl claims that a precipitate of 

 K2ZnFe(CN)e or Zn 2 Fe(CN)e is formed when urines containing zinc 

 are subjected to this test and that this precipitate resembles the 

 precipitate secured with protein solutions. In the case of human 

 urine a reaction was obtained when 0.000022 gram of zinc per cubic 

 centimeter was present. Schmiedl further found that the urine col- 

 lected from rabbits housed in zinc-lined cages possessed a zinc content 

 which was sufficient to yield a ready response to the test. 



Proteoses may also be detected by this . test. To differentiate 

 albumin from proteose perform the coagulation test (see above). 



GLOBULIN 



Serum globulin is not a constituent of normal urine but frequently 

 occurs in the urine under pathological conditions and is ordinarily 



