URINE. 325 



sodium nitrite to the acid-alcohol mixture before warming on the 

 water-bath. Try this modification also. 



5. Salkowski's Test. Render 5 c.c. of urine alkaline with a 

 few drops of a 10 per cent sodium carbonate solution and add a 

 10 per cent solution of calcium chloride, drop by drop, until the 

 supernatant fluid exhibits the normal urinary color when the con- 

 tents of the test-tube are thoroughly mixed. Filter off the pre- 

 cipitate, and after washing it, place it in a second tube with 95 

 per cent alcohol. Acidify the alcohol with hydrochloric acid and, 

 if necessary, shake the tube to bring the precipitate into solution. 

 Heat the solution to boiling and observe the appearance of a green 

 color which changes through blue and violet to red; if no bile is 

 present the solution does not undergo any color change. This test 

 will frequently exhibit greater delicacy than Gmelin's test. Steens- 

 ma's suggestions mentioned under Huppert's Reaction, p. 324, ap- 

 ply in connection with this test also. 



4. Hammarsten's Reaction. To about 5 c.c. of Hammarsten's 

 reagent 1 in a small evaporating dish add a few drops of urine. A 

 green color is produced. If more of the reagent is now added the 

 play of colors as noted in Gmelin's test may be obtained. 



5. Smith's Test. To 2-3 c.c. of urine in a test-tube add care- 

 fully about 5 c.c. of dilute tincture of iodine ( i : 10) so that the 

 fluids do not mix. A green ring is observed at the point of con- 

 tact. 



6. Salkowski-Schippers Reaction. Neutralize the acidity of 

 10 c.c. of the urine under examination with a few drops of a 

 dilute solution of sodium carbonate, and add 5 drops of a 20 per 

 cent solution of sodium carbonate and 10 drops of a 20 per cent 

 solution of calcium chloride. Filter off the resultant precipitate 

 upon a hardened filter-paper -and wash it with water. Remove 

 the precipitate to a small porcelain dish, add 3 c.c. of an acid- 

 alcohol mixture 2 and a few drops of a dilute solution of sodium 

 nitrite and heat. The production of a green color indicates the 

 presence of bile pigments. 



Tests for Bile Acids. 



i. Pettenkofer's Test. To 5 c.c. of urine in a test-tube add 5 

 drops of a 5 per cent solution of sucrose. Now incline the tube, 



1 Hammarsten's reagent is made by mixing i volume of 25 per cent nitric acid 

 and 19 volumes of 25 per cent hydrochloric acid and then adding i volume of this 

 acid mixture to 4 volumes of 95 per cent alcohol. 



2 Made by adding 5 c.c. of concentrated hydrochloric acid to 95 c.c. of 96 per 

 cent alcohol. 



