FECES. 179 



(d) Acid-Hcematin. Examine some of the ethereal extract from 

 Experiment (b) spectroscopically. Note the typical spectrum of 

 acid-hsematin (see Absorption Spectra, Plate II). 



7. Hydrobilirubin. Schmidt's Test. Rub up a small amount of 

 feces in a mortar with a concentrated aqueous solution of mercuric 

 chloride. Transfer to a shallow, flat-bottomed dish and allow to 

 stand 6-24 hours. The presence of hydrobilirubin will be indicated 

 by a deep red color being imparted to the particles of feces con- 

 taining this pigment. This red color is due to the formation of 

 hydrobilirubin-mercury. If unaltered bilirubin is present in any 

 portion of the feces that portion will be green in color due to the 

 oxidation of bilirubin to biliverdin. 



Another method for the detection of hydrobilirubin is the fol- 

 lowing: Treat the dry feces with absolute alcohol acidified with 

 sulphuric acid and shake thoroughly. The acidified alcohol extracts 

 the pigment and assumes a reddish color. Examine a little of 

 this fluid spectroscopically and note the typical spectrum of hydro- 

 bilirubin (Absorption Spectra, Plate II). 



8. Bilirubin. 1 (a) Gmelin's Test. Place a few drops of con- 

 centrated nitric acid in an evaporating dish or on a porcelain test- 

 tablet and allow a few drops of feces and water to mix with it. 

 The usual play of colors of Gmelin's test is produced, i. e., green, 

 blue, violet, red and yellow. If so desired, this test may be exe- 

 cuted on a slide and observed under the microscope. 



(b) Huppert's Test. Treat the feces with water to form a semi- 

 fluid mass, add an equal amount of milk of lime, shake thorough- 

 ly and filter. Wash the precipitate with water, then transfer both 

 the paper and the precipitate to a small beaker or flask, add a small 

 amount of 95 per cent alcohol acidified slightly with sulphuric acid 

 and heat to boiling on a water-bath. The presence of bilirubin is 

 indicated by the alcohol assuming a green color. 



Steensma advises the addition of a drop of a 0.5 per cent solu- 

 tion of sodium nitrite to the acid-alcohol mixture before warming 

 on the water-bath. Try this modification also. 



9. Bile Acids. Extract a small amount of feces with alcohol 

 and filter. Evaporate the filtrate on a water-bath to drive off the 

 alcohol and dissolve the residue in water made slightly alkaline with 

 potassium hydroxide. Upon this aqueous solution try any of the 

 tests for bile acids given on page 156. 



lr The detection of bilirubin in the feces is comparatively simple provided it 

 is not accompanied by other pigments. When other pigments are present, how- 

 ever, it is difficult to detect the bilirubin and at times, may be found impossible. 





