XVII.] INTESTINE. BILE. PANCREATIC JUICE. 185 



acid, to filter and use the filtrate ; before filter- 

 ing, the bile may be diluted four or five times 

 with water. 



. The mucin may also be removed by adding an excess 

 of alcohol, the filtrate from this should be evaporated 

 to dryness, and the residue dissolved in water. 



3. Grnelin's test for Mle-pigment. To a small 

 quantity in a test-tube add di'op by drop, nitric 

 acid, yellow with nitrous acid, shaking after each 

 drop ; the yellowish green colour becomes first a 

 dark green, then blue, then violet, then red, and 

 finally a dirty yellow. The blue and violet 

 colours are less obvious than the rest. Eepeat 

 the test in the following form ; place a drop of 

 bile on a porcelaia slab, and place a drop of 

 yellow nitric acid so that it runs into the drop 

 of bile ; where the fluids mingle, zones of colour, 

 green, blue, violet, red and yellow, fi:om the bile 

 to the acid, are seen, 



4, PettenJcofer's test for bile-acids^. To a little bile 

 in a test-tube, add one drop of a 10 p.c. solution 

 of cane-sugar (or a small particle of sugar) and 

 shake. Add strong sulphuric acid to nearly the 

 same amount as the bile taken, inclining the 



^ Bile-salts may be prepared in the following manner. Enb ox- 

 gall with animal charcoal into a thin paste. Evaporate on a water 

 bath to complete dryness, and extract with absolute alcohol. The 

 alcoholic filtrate should be colourless. Add to it anhydrous ether as 

 long as any precipitate is produced, and let it stand. The precipitate 

 either crystaUizea out or falls to the bottom as a thick viscid syrup ; 

 it is a mixture of sodium glycocholate and taurocholate. 



