180 THE URINE. 



TESTS FOR ALBUMIN IN THE URINE. 



If the urine is not clear it must be filtered before 

 testing. 



380. THE HEAT, OR BOILING, TEST. Heat the urine 

 to boiling in a test-tube, then acidify with a few drops of 

 concentrated nitric acid. If albumin is present, a white 

 precipitate remains. The earthy phosphates precipitate on 

 boiling, but are soluble in acids. 



381. HELLER'S TEST. Pour half an inch of concen- 

 trated nitric acid into a small test-tube. From a pipette, 

 the end of which is held just above the surface of the acid, 

 drop the urine slowly or hold the tube in a slanting posi- 

 tion and slowly pour upon the acid an equal volume of 

 urine. If albumin is present a white cloud forms at the 

 point of contact of the two liquids. If the amount is ex- 

 ceedingly small, it may not appear for half an hour. (If 

 biliary pigments are present the ring may be colored. See 

 test for these, Experiment 285.) 



382. Acidify 2 or 3 cubic centimeters of potassium 

 ferrocyanid solution with about 1 cubic centimeter of acetic 

 acid, and fill the test-tube half full of urine. Albumin 

 gives a white, cloudy precipitate. An excess of ferrocyanid 

 interferes with the accuracy of the test. 



383. Add to the urine in a test-tube about one-sixth 

 of its volume of a saturated solution of sodium chlorid, 

 acidify with acetic acid, and boil the upper part of the 

 liquid, holding the tube by the bottom. Albumin gives a 

 white precipitate, which shows plainly above the clear 

 liquid in the lower part of the tube. 



Each of these tests has some objections to it which must be 

 recognized in interpreting the results. By the action of heat and 

 nitric acid some of the albumin is decomposed; hence the first test 



