BILE 



211 



(a) Examine them under the microscope and compare with Fig. 58. 



(b) Heat a crystal upon platinum foil. The taurine at first melts, then turns 

 brown, and finally carbonizes as the temperature is raised. Note the suffocating 

 odor. What is it? 



FIG. 58. TAURINE. 



(c) Test the solubility of the crystals in water and in alcohol. 



(d) Grind up a crystal with four times its volume of dry sodium carbonate and 

 fuse on platinum foil. Cool the residue, transfer it to a test-tube, and dissolve it in 

 water. Add a little dilute sulphuric acid and note the odor of hydrogen sulphide. 

 Hold a piece of filter paper, moistened with a small amount of lead acetate, over 

 the opening of the test-tube and observe the formation of lead sulphide. 



'^o^tf 

 &3&X 



c=^ 



FIG. 59. GLYCOCOLL. 



10. Preparation of Glycocoll. Concentrate the alcoholic filtrate from the last 

 experiment (9) until no more alcohol remains. The glycocoll is present here in the 

 form of an hydrochloride and may be liberated from this combination by the addi- 

 tion of freshly precipitated lead hydroxide or by lead hydroxide solution. Remove 

 the lead by hydrogen sulphide. Filter and decolorize the filtrate by animal char- 

 coal. Filter again, concentrate the filtrate, and set it aside for crystallization. 

 Glycocoll separates as colorless crystals (Fig. 59). 



