60 HANDBOOK FOE BIO-CHEMICAL LABORATORY. 



shaken with its J vol. chloroform and considerable water. The 

 chloroform is separated and washed once or twice with water 

 and the chloroform now distilled off. The residue, consisting 

 of impure urobilin, is washed with ether, which removes 

 considerable quantities of a red coloring matter, and leaves 

 the urobilin as brown amorphous masses. 



Properties. Urobilin, according to Jaffe, is amorphous, red, 

 dingy red or reddish yellow, according to the method of prep- 

 aration. It is readily soluble in alcohol, amyl alcohol, acetic 

 ether, and chloroform, but less readily in ether or water. It 

 is soluble in alkalies, and is incompletely precipitated from 

 the alkaline solution by the addition of acid. Its alkaline 

 solutions give insoluble combinations with salts of the heavy 

 metals, such as zinc and lead. A neutral solution of urobilin 

 gives a green fluorescence, and the acid solution shows a faint 

 absorption-band between b and F, which borders on F, or in 

 greater concentration extends over F. The alkaline solutions 

 show a darker or more sharply defined absorption-band, almost 

 midway between b and F. 



Glycuronic Acid, 



C 6 H 10 7 . 



Preparation. Puree or Indian yellow is rubbed fine with 

 water in a mortar, forming a thick mass. This is acidified 

 with hydrochloric acid, filtered, and thoroughly washed with 

 water. The euxanthic acid thus obtained is dissolved in hot 

 alcohol, filtered, and allowed to stand to crystallize as beautiful 

 yellow needles. This crystallization is repeated again so as to 

 obtain pure euxanthic acid. One part of the euxanthic acid 

 is treated with 150 parts water and heated, in a Papin's di- 

 gester supplied with a thermometer, first to boiling, allowing 

 the cover of the digester to be open. After closing the cover 

 heat for an hour, keeping the temperature at 120-125 C. 

 On cooling the liquid is filtered, leaving the crystals of unde- 



