242 MR. E. SCHUNCK ON THE 



not exist in them ready formed nor as reduced indigo, and 

 that the presence of oxygen is not essential to its formation, 

 but that it owes its origin to the presence of a peculiar 

 substance, soluble in water, alcohol and ether which by the 

 action of acids is decomposed into indigo-blue, to which I have 

 given the name of Indican, also a peculiar kind of sugar and 

 a small quantity of other products. After having investigated 

 the properties of this substance and its products of decom- 

 position, I conceived it to be a matter of great interest to 

 ascertain in what state indigo-blue exists in those urines, in 

 which its presence is not indicated by the external appearance 

 but is only made manifest by treatment with various reagents. 

 That such urines should contain a body resembling indican 

 seemed indeed exceedingly probable, since the same reagents 

 which produce indigo-blue from indican lead in most cases to, 

 the development of the blue colour in particular kinds of urine* 

 The extreme rarity however of these kinds of urine appeared 

 to present an insuperable obstacle to the further investigation 

 of the subject, and I therefore resolved to astertain whether 

 any conclusions could be arrived at from an examination of 

 ordinary healthy urine. 



When muriatic or sulphuric acid is added to urine, the 

 mixture on being heated becomes brown and begins to deposit 

 dark brown flocks, which increase in quantity when the heat- 

 ing is continued. When these flocks are filtered off, washed 

 and dried, they form a compact dark brown mass, from which 

 cold alcohol extracts a resinous matter, leaving undissolved a 

 brown powder, which dissolves however in a boiling mixture 

 of alcohol and ammonia. This powder contains nitrogen and 

 so much resembles indifuscine, one of the products of the 

 decomposition of indican, as almost to lead one to suspect their 

 identity. Its composition however, though it stands, as I 

 have ascertained, in a certain relation to that of indigo-blue, 

 is quite different from that of indifuscine. Now if the liquid 

 filtered from these flocks be mixed with a salt of oxide of 



