434 PHYSIOLOGICAL CHEMISTRY 



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 1 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. 



8. Bonanno's Reaction. 2 Place 5-10 c.c. of the urine under examination in a 

 small porcelain evaporating dish and add a few drops of Bonanno's reagent. 3 If 

 bile is present an emerald-green color will develop. Bonanno says the reaction is 

 not interfered with by any known normal or pathological urinary constituent. 



Tests for Bile Acids 



1. Sucrose H 2 SO 4 Test (Pettenkofer). 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, run about 

 2-3 c.c. of concentrated sulphuric acid carefully down the side and note the 

 red ring at the point of contact. Upon sUghtly agitating the contents of the 

 tube the whole soultion gradually assumes a reddish color. As the tube be- 

 comes warm, it should be cooled in running water in order that the tempera- 

 ture may not rise above 7oC. 



It is claimed that this test is not satisfactory in the presence of 

 protein and chromogenic substances which yield interfering colors 

 with sulphuric acid. 



2. Furfural H 2 SO 4 Test (Mylius). To approximately 5 c.c. of urine in a 

 test-tube add 3 drops of a very dilute (i : 1000) aqueous solution of furfural, 



HC C.CHO. 



Now incline the tube, run about 2-3 c.c. of concentrated sulphuric acid carefully 

 down the side and note the red ring as above. In this case also, upon shaking 

 the tube, the whole solution is colored red. Keep the temperature below 7oC. 

 as before. 



3. Foam Test (v. Udransky). To 5 c.c. of urine in a test-tube add 3-4 drops 

 of a very dilute (i : 1000) aqueous solution of furfural. Place the thumb over the 

 top of the tube and shake until a thick foam is formed. By means of a small 

 pipette add 2-3 drops of concentrated sulphuric acid to the foam and observe the 

 dark pink coloration produced. 



4. Surface Tension Test (Hay). This test is based upon the principle that 

 bile acids have the property of reducing the surface tension of fluids in which 

 they are contained. The test is performed as follows: Cool about 10 c.c. of 

 urine in a test-tube to i7C. or lower, and sprinkle a little finely pulverized sul- 

 phur upon the surface of the fluid. The presence of bile acids is indicated if the 



1 Made by adding 5 c.c. of concentrated hydrochloric acid to 95 c.c. of 96 per cent, 

 alcohol. 



2 II Tommasi, 2, No. 21. 



3 This reagent may be prepared by dissolving 2 grams of sodium nitrite in 100 c.c. of 

 concentrated hydrochloric acid. 



