BILE. 



159 



purple is noted in the chloroform while the acid assumes a marked 

 green fluorescence. 



(e) Schiff's Reaction.- To a little cholesterol in an evaporating 

 dish add a few drops of Schiff's reagent. 1 Evaporate to dryness 



FIG. 42. 



CHOLESTEROL. 



over a low flame and observe the reddish-violet residue which 

 changes to a bluish-violet. 



9. Preparation of Taurine. To 300 c.c. of bile in a casserole 

 add 100 c.c. of hydrochloric acid and heat until a sticky mass 

 (dyslysin) is formed. This point may be determined by drawing 

 out a thread-like portion of the mass by means of a glass rod, and 

 if it solidifies immediately and assumes a brittle character we may 

 conclude that all the taurocholic and glycocholic acid has been 

 decomposed. Decant the solution and concentrate it to a small vol- 

 ume on the water-bath. Filter the hot solution to remove sodium 

 chloride and other substances which may have separated, and 

 evaporate the filtrate to dryness. Dissolve the residue in 5 per 

 cent hydrochloric acid and precipitate with ten volumes of 95 per 

 cent alcohol. Filter off the taurine and recrystallize it from hot 

 water. (Save the alcoholic filtrate for the preparation of glycocoll, 

 page 160.) Make the following tests upon the taurine crystals: 



(a) Examine them under the microscope and compare with 

 Fig. 43, p. 1 60. 



(b) Heat a crystal upon platinum foil. The taurine at first 



1 Schiff's reagent consists of a mixture of three volumes of concentrated 

 sulphuric acid and one volume of 10 per cent ferric chloride. 



