HANDBOOK FOR BIO-CHEMICAL LABORATORY. 27 



hydrate, which precipitates the sulphuric acid ; allow the 

 precipitate to settle, wash by decautation with boiling water, 

 and concentrate the solution by evaporation. If an excess of 

 Ba(OH) 2 has been added, remove this by passing CO, through 

 the solution, boiling and then filtering, and allowing to stand 

 until crystals commence to form. The crystals are removed 

 from the mother-liquor and this concentrated further, and 

 the process repeated as long as crystals continue to separate 

 out. The glycocoll is purified by recrystallization from water. 

 Properties. Glycocoll occurs as fine, hard, colorless, 

 rhombic crystals or four-sided prisms. The crystals have a 

 sweetish taste, are soluble in 4.3 parts cold water, very slightly 

 soluble in spirits of wine, and insoluble in cold absolute alco- 

 hol and ether. It combines with acids, bases, and neutral 

 salts. Glycocoll dissolves copper hydroxide in alkaline solu- 

 tion, but does not reduce at the boiling temperature, but de- 

 posits on cooling dark blue needles if the liquid is sufficiently 

 concentrated. Its solutions possess an acid reaction. When 

 heated to 232-236 C., glycocoll becomes brown, evolves gas- 

 bubbles, and melts. A solution of glycocoll is colored red by 

 ferric chloride. Its combination with HC1 is soluble in water 

 and alcohol. 



Taurin, C 2 H,NS0 3 . 



Preparation. Mix ox-bile with strong hydrochloric acid so 

 as to precipitate the mucoid substances, filter, and boil the 

 filtrate for several hours. After allowing to cool and to de- 

 posit the dyslysin and choloidic acid concentrate the liquid 

 on the water-bath, filter so as to remove any common salt or 

 other substances which may have separated. The filtrate is 

 treated with strong alcohol, which precipitates the taurin with 

 some NaCl. This precipitate is washed with alcohol, dried, 

 and dissolved in the smallest quantity of boiling water possi- 

 ble. On cooling the taurin deposits in fine four-sided prisms 

 which may be further purified by recrystallization from water. 



