32 



acid is clear, add a single crystal of cane sugar, warm, and 

 the acid becomes 3-ellow from the development of a small 

 amount of nitrous acid), shaking after each drop; the 

 yellowish green color becomes first a dark green, then blue, 

 then violet, then red, and finally a dirty yellow. The blue 

 and violet colors are less obvious than the rest. 



Repeat the test in the following way : place a drop of bile 

 in a porcelain evaporating dish, and place a drop of yellow 

 nitric acid .so that it runs into the drop of bile ; where the 

 fluids mingle, zones of color, green, blue, violet, red and 

 yellow, from the bile to the acid, are seen. 



140. Add a little bile to some .starch mucilage as in .sali- 

 vary digestion. Test for any reducing sugar. In this ex- 

 periment fre.sh bile should be used as the formalin acts as a 

 reducing agent. 



141. To 5 cc. of undiluted bile add an equal volume of 

 water and .some alcohol to precipitate the mucin. Filter 

 and divide the filtrate into two portions ; to one portion 

 add some hydrochloric acid which causes a precipitation 

 of glycocholic acid ; to the other portion add a little of a 

 I % solution of neutral lead acetate which throws down lead 

 glycocholate. Remove this by filtration, and to the filtrate 

 add a little i % solution of basic lead acetate, which gives a- 

 further precipitation of lead taurocholate. [I,ong.] 



142. Add a few drops of oleic acid to 5 cc. of bile in a test- 

 tube, shake well and at once place a drop of the mixture on 

 a slide and examine, under the microscope, the numerous 

 fatty globules. Place the test-tube with the bile in a warm 

 "bath for an hour or so, shaking occasionally and then ex- 

 amine a drop with the microscope ; comparatively few fatty 

 globules will be seen. The oleic acid has combined with 

 the base of the bile-salts to form a soap. 



143. Prepare three test-tubes as follows: (i) In one 

 test-tube put 5 cc. of bile and a drop of oleic acid. (2) In 

 another 5 cc. of water. (3) In another 5 cc. of bile. To 



