188 



UEOMELANINE. 



8. Separate kryptophanic acid by dissolving its 

 lead- salt in excess f lead acetate, in which urochrome 

 lead is insoluble. 



Urocyanine. Urine from cholera patients in the 

 early stage of reaction, is cautiously boiled with nitric 

 acid. A blue colour is often produced, and a blue 

 deposit sometimes formed. The latter is soluble in 

 alcohol, forming a dichroic purple blue solution giving, 

 before the spectroscope, a broad absorption band in 

 yellow and green. 



AaBC 



AaBC D 



Spectrum of choleraic urocyanine. 



Eb F 



HH' 



Spectrum of choleraic urorubine. 



Uromelanine, C 36 H 43 N 7 10 . 1. Evaporate fresh urine 

 to one tenth, filter, evaporate the nitrate to a syrup, and 

 set aside to crystallise. Decant the mother liquor, 

 dilute with one volume of water, and treat with 



