47 



and wash with water. The reaction should be alkaline if the 

 bile is fresh. 



159. To 5 cc. of bile in a test tube add 10 cc. water and 

 then some strong alcohol. This produces a precipitate of 

 mucin with some pigment entangled. 



160. Mucin is also precipitated by the addition of acetic 

 acid to bile. Perform this lest using the same proportions as 

 in 159. Filter off the mucin. 



161. To a portion of the filtrate add a little hydrochloric 

 acid and potassium ferrocyanide. A blue color indicates the 

 presence of iron. The experiment may be modified by placing 

 some thin sections of liver in a solution of potassium ferro- 

 cyanide for a few minutes and then in dilute hydrochloric acid. 

 The sections turn bluish from the formation of prussian blue. 

 With the microscope blue granules may be seen in some of the 

 hepatic cells. 



162. Test another portion of the filtrates for proteids, 

 also for chlorides and sulphates. Fresh human bile gives no 

 spectrum, but the bile of the ox, mouse and some other animals 

 does. 



163. Pettenkofer's Test for Bile Acids. Take 2 cc. of 

 clear diluted bile in a test tube and add 4 drops of a 10% 

 solution of cane sugar. Add strong sulphuric acid, drop by 

 drop, cooling the tube in a dish of cold water immediately 

 after adding the acid. Not more than 2 cc. of the acid should 

 be used. Too much heat causes carbonization of the sugar 

 and the test is ruined. If bile acids are present, the fluid at 

 first becomes opaque, then clear, and successively brown, red 

 and purple. It may require an hour or more to accomplish 

 this test. This reaction depends upon the production of fur- 

 furol (C4H3OCHO) by the destruction of the sugar when the 

 sulphuric acid is added. Furfurol in turn combines with cho- 

 lalic acid, formed by the action of the sulphuric acid on the 

 bile acids, giving the color. Some other substances, as mor- 

 phine, albumin, etc., give a very similar color, and the test 

 must, therefore, be used with caution. In very dilute solu- 

 tions of bile the reaction does not appear and cannot be used 

 satisfactorily in testing urine fc)r the pesence of bile. 



Pettenkofer's test may also be quite satisfactorily per- 

 fomed more quickly by putting a little of the bile in a por- 



