208 PHYSIOLOGICAL CHEMISTRY 



small evaporating dish add a few drops of diluted bile. A green color is produced. 

 If more of the reagent is now added the play of colors as observed in Gmelin's test 

 may be obtained. 



(f) Smith's Test. To 2-3 c.c. of diluted bile in a test-tube add carefully about 

 5 c.c. of dilute tincture of iodine (i : 10) so that the fluids do not mix. A play of 

 colors, green, blue and violet, is observed. In making this test upon the urine ordin- 

 arily only the green color is observed. 



(g) Salkowski-Schipper's Reaction. To 10 c.c. of diluted bile in a test-tube 

 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 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. 



(h) Bonanno's Reaction. 2 Place 5-10 c.c. of diluted bile in a small porcelain 

 evaporating dish and add a few drops of Bonanno's reagent. 3 An emerald-green 

 color will develop. 



5. Tests for Bile Acids. (a) Sucrose-H 2 SO 4 Test (Pettenkofer). To 5 c.c 

 of diluted bile in a test-tube add 5 drops of a 5 per cent solution of sucrose. Now 

 run about 2-3 c.c. of concentrated sulphuric acid carefully down the side of the 

 tube and note the red ring at the point of contact. Upon slightly agitating the 

 contents of the tube the whole solution gradually assumes a reddish color. As 

 the tube becomes warm, it should be cooled in running water in order that the 

 temperature of the solution 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. 



(b) Furfural-H 2 SO 4 Test. Mylius's Modification of Pettenkofer's Test. 

 To approximately 5 c.c. of diluted bile in a test-tube add 3 drops of a very dilute 

 (i :iooo) aqueous solution of furfural, 



HC CH 



II II 

 HC C-CHO. 



\/ 

 O 



Now run about 2-3 c.c. of concentrated sulphuric acid carefully down the side of 

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

 tube the whole solution is colored red. Keep the temperature of the solution be- 

 low 7oC. as before. 



(c) Foam Test (v. Udransky). To 5 c.c. of diluted bile 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 the tube until a thick foam is formed. By 

 means of a small pipette add 2-3 drops of concentrated sulphuric acid to the foam 

 and note the dark pink coloration produced. 



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. 



concentrated hydrochloric aci 



epa 

 d. 



