68 LABORATORY WORK IN PHYSIOLOGICAL CHEMISTRY- 



Use the diluted bile for the following reactions: 



(a) Add acetic acid drop by drop to 5 c.c. of the bile. 



Is this precipitate mucin? How could you prove it? Filter 



and test the filtrate for protein. What is the most suitable 



test? 



(6) To 1 c.c. of olive-oil add 10 c.c. of water and shake 



thoroughly. Allow it to stand in the rack. 



(c) To 1 c.c. of olive-oil add 10 c.c. of diluted bile. Allow 

 this to stand. Compare the permanency of the emulsion. 



(d) To 10 c.c. of a gastric digestion mixture add diluted 

 bile, drop by drop. What is this precipitate and its signifi- 

 cance? 



CONJUGATE BILE ACIDS. 



These are present as the sodium salts of taurocholic and 

 glycocholic acids, and are formed by the combination of 

 cholalic acid with taurin and glycocoll respectively. Tauro- 

 cholic acid, by virtue of the taurin, contains sulphur and 

 has a solvent action on the more insoluble glycocholic acid. 

 It is more abundant in the bile of carnivora, while glyco- 

 cholic acid predominates in that of man and herbivora. 

 Together they tend toward rendering the cholesterol and 

 lecithin more soluble and exert a distinctly inhibitory action 

 on the heart, slowing its rhythm. 



Pettenkofer's Test. Place 5 c.c. of concentrated H 2 S0 4 in 

 a clean dry test-tube. In another test-tube place 5 c.c. of 

 diluted bile to which has been added a few drops of a 2 per 

 cent cane-sugar solution or a solution of furfurol 1 : 1000. Pour 

 the diluted bile carefully down the sides of the tube con- 

 taining the H 2 S0 4 so that the two fluids do not mix. (Method 

 of stratification.) Notice the coloration at the line of con- 

 tact of the two solutions. Shake the tube slightly, allowing 

 a little more of the bile to come in contact with the H 2 S0 4 . 



