46 ORGANIC CONSTITUENTS. 



bilifulvin, must be decomposed by an excess of carbonate 

 of soda. The precipitate is then to be extracted with absolute 

 alcohol, and the soda carefully precipitated from this solution 

 by dilute sulphuric acid. On evaporating the alcoholic solu- 

 tion to dryness, we obtain hilin. 



The composition of bilin is not accurately determined. It 

 is easy to show that it contains nitrogen, by heating it with 

 an alkali, in which case it develops ammonia. Lehmann always 

 found traces of sulphur in it. 



Bilin forms a gummy, pale yellow mass, which when quickly 

 dried and pulverized, yields a white powder, devoid of odour 

 and possessing a singular sweetish-bitter taste, most perceptible 

 at the base of the tongue and on the posterior fauces. Berzelius 

 suggests that the sweetness may be owing to the admixture of 

 a little glycerin.^ It is freely soluble in water and in alcohol, 

 but not in ether; in fact it may be precipitated by ether from 

 its alcoholic solution. When recently prepared, it is perfectly 

 neutral. Heated to 212°, it begins to swell ; at a higher tem- 

 perature it becomes brown, develops a peculiar odom', and 

 when inflamed, burns with a bright clear flame, leaving a 

 porous ash. 



An aqueovis solution of bilin is not affected by acids, nor by 

 earthy or metallic salts ; neither does chlorine seem to induce 

 any peculiar change. A concentrated solution of potash sepa- 

 rates an oleaginous tough mass, (a compound of bilin and 

 potash,) which is soluble in water and in alcohol. 



Bilin is remarkable for the facility with which it undergoes 

 metamorphoses. An aqueous or alcoholic solution in vacuo 

 soon assumes an acid reaction. Its decomposition is accelerated 

 by warmth, by the presence of organic matters, as mucus, &c., 

 and more especially by the action of the mineral acids. 



Metamorphoses of Bilin. Bilin and Jiyclrochloric acid. On 

 digesting bilin with dilute hydrochloric acid, five distinct sub- 

 stances are ultimately obtained, three of which are insoluble in 

 water, and have received from Berzelius the names oi fellinic 

 acid, cholinic acid, and dyslysin ; the remaining two being 



' As the bile contains oleate, niargarate, and stearate of soda, there is no difficulty 

 in accounting for the presence of glycerin. 



