BILE. 155 



reddish-yellow. Repeat this test with different dilutions of bile 

 and observe its delicacy. 



(b) Rosenbach's Modification of Gmelin's Test. Filter 5 c.c. 

 of diluted bile through a small filter paper. Introduce a drop of 

 concentrated nitric acid into the cone of the paper and note the suc- 

 cession of colors as given in Gmelin's test. 



(c) Nakayamas Reaction. To 5 c.c. of diluted bile in a test-tube 

 add an equal volume of a 10 per cent solution of barium chloride, 

 centrifugate the mixture, pour off the supernatant fluid and heat 

 the precipitate with 2 c.c. of Nakayama's reagent. 1 In the presence 

 of bile pigments the solution assumes a blue or green color. 



(d) Huppert's Reaction. Thoroughly shake equal volumes of 

 undiluted bile and milk of lime in a test-tube. The pigments unite 

 with the calcium and are precipitated. Filter off the precipitate, 

 wash it with water and transfer to a small beaker. Add alcohol 

 acidified slightly with hydrochloric acid and warm upon a water- 

 bath until the solution becomes colored an emerald green. 



In examining urine for bile pigments, according to Steensma, this 

 procedure may give negative results even in the presence of the 

 pigments, owing to the fact that the acid-alcohol is not a sufficiently 

 strong oxidizing agent. He therefore suggests the addition of a 

 drop of a 0.5 per cent solution of sodium nitrite to the acid-alcohol 

 mixture before warming on the water-bath. Try this modifica- 

 tion also. 



(e) Hanunarstcn's Reaction. To about 5 c.c. of Hammarsten's 

 reagent 2 in a small evaporating dish add a few drops of diluted bile. 

 A green color is produced. If more of the reagent is now added 

 the play of colors as observed in Gmelin's test may be obtained. 



(/) Smith's Test. To 2-3 c.c. of diluted bile in a test-tube add 

 carefully about 5 c.c. of dilute tincture of iodine (i :io) so that the 

 fluids do not mix. A play of colors, green, blue and violet, is 

 observed. In making this test upon the urine ordinarily only the 

 green color is observed. 



(g) Salkowski-S chip per s Reaction. To 10 c.c. of diluted bile 

 in a test tube add 5 drops of a 20 per cent solution of sodium 

 carbonate and 10 drops of a 20 per cent solution of calcium chloride. 

 Filter off the resultant precipitate upon a hardened filter-paper and 



1 Prepared by combining 99 c.c. of alcohol and i c.c. of fuming hydrochloric 

 acid containing 4 grams of ferric chloride per liter. 



2 Hammarsten's reagent is made by mixing i volume of 25 per cent nitric 

 acid and 19 volumes of 25 per cent hydrochloric acid and then adding i volume 

 of this acid mixture to 4 volumes of 95 per cent alcohol. 



