CH. XII.] BILE PIGMENTS. 307 



suspected urine. The fluid rapidly acquires a deep blue tint if 

 blood pigment is present. Should the untreated fluid also develop 

 a blue tint, the test should be repeated, the control tube being treated 

 with i cc. of a normal urine. By following this procedure the test 

 is a very conclusive one. The reaction can be applied to an acid 

 ether extract prepared by the method given in the above exercise. 



5. Bile. 



The constituents of the bile are found in urine when 

 the bile duct is obstructed by a calculus or by catarrh. 

 The bile is absorbed into the lymphatics, passes into the 

 circulation and reaches all parts of the body, the pigments 

 causing a staining of the various tissues. The condition 

 is known as jaundice. 



The absence of bile salts from the urine does not 

 exclude the possibility of the presence of bile pigments. 

 With continued obstruction of the bile passages the 

 formation of bile salts seems to decrease. Urine contain- 

 ing bile often has a characteristic appearance. 



377. Cole's test for bile pigments. Treat 10 to 15 cc. 

 of the urine with 2 drops of saturated magnesium sulphate and 

 proceed as directed in Ex. 318. If a hand centrifuge is available, the 

 test is more sensitive if an excess of barium chloride is added to the 

 unheated urine and the precipitate driven drown by spinning in the 

 machine. The supernatant fluid is poured off as cleanly as possible, 

 the precipitate stirred with the alcohol and sulphuric acid, trans- 

 ferred to a test-tube and boiled with the potassium chlorate. 



In a certain number of cases the result is obscured by the 

 presence of certain other pigments. In such cases to render the 

 test more delicate, pour off the alcoholic solution from the barium 

 sulphate into a dry tube. Add about one-third its volume of 

 chloroform and mix. To the solution add about an equal volume 

 of water, place the thumb on the tube, invert once or twice and 

 allow the chloroform to separate. It contains the bluish pigment 

 in solution. 



