3*8 URINE. [CH. XII. 



12. Indican. 



Indican is the potassium salt of indoxyl sulphuric 

 acid, and is thus one of the ethereal sulphates (seep. 281). 

 Indoxyl is 



CH 



HG C C.OH 



HO C C.H 



\/\/ 



CH NH. 



Indican is 



CH 



/\ 



HC C C.O.SOaK 



HC C CH 



\/\/ 



CH NH. 



Indoxyl arises from the bacterial decomposition of 

 tryptophane in the intestine, thus differing from the 

 other ethereal sulphates which are normal tissue meta- 

 bolites (see p. 282). The excretion of indican is of import- 

 ance as a measure of the amount of putrefaction occurring, 

 generally in the intestine, but sometimes in a large abscess. 



393. Jaffe's test. Treat 5 cc. of urine with a rather larger 

 volume of concentrated hydrochloric acid and about 2 cc. of chloro- 

 form. Add a single drop of 5 per cent, potassium chlorate and mix. 

 Allow the chloroform to settle and examine its colour. If it be blue, 

 indican is present. If not, add another drop of the chlorate and mix 

 again. If no blue colour be found in the chloroform, indican is 

 absent. 



NOTE. The extraction with chloroform is best done by repeatedly pour- 

 ing the mixture from one tube to another. It is essential to add at least an 

 equal volume of strong hydrochloric acid to liberate free indoxyl. This is 

 oxidised to indigo blue, which is soluble in chloroform. 



Horse's and cow's urine nearly always contain indican. If procurable 

 they should be used for the sake of experience. 



