1880.] 



Colouring Matters of Human Urine. 



251 



chemical tests showed a large amount of urobilin, it was precipitated by 

 neutral and basic lead acetate respectively, and filtered ; if the nitrate 

 gave an absorption spectrum, it was re-precipitated until the band disap- 

 peared, the precipitates were united, extracted with alcohol acidulated 

 either with hydrochloric or sulphuric acid, and filtered. The nitrate was 

 of a fine red colour, giving the dark band at F. This fluid, in small 

 quantities at a time, was put into a separating funnel, a large quantity 

 of water added and then pure chloroform, the whole repeatedly 

 shaken and then allowed to stand. The red chloroform layer was 

 separated off and filtered, when it was again examined and found to 

 give in every instance the original spectrum ; the chloroform was now 

 evaporated off and the residue repeatedly dissolved in chloroform, 

 finally on evaporation a brown-red, amorphous, shiny residue was ob- 

 tained, which was perfectly soluble in alcohol, chloroform, nitric acid, 

 hydrochloric acid, acetic acid, lactic acid, acidulated water, and partly 

 soluble in ether, in water, and in benzol, but quite insoluble in bisul- 

 phide of carbon. I fully describe the spectra of the various solu- 

 tions, which are shown in Chart I, and it will be seen that the same 

 pigment was present in every solution, and since by the action of 

 different solvents and reagents, this pigment could not be separated 

 into more than one, 1 conclude that pure urobilin was obtained and 

 urobilin only. I have also endeavoured to show that the pigment ob- 

 tained was in combination with the sulphuric acid, when prepared by the 

 sulphuric acid method, as it was found to contain sulphur, in addition 

 to carbon, hydrogen, oxygen and nitrogen, which was absent and 

 replaced by chlorine when it was prepared by the hydrochloric acid 

 method. The conclusions which this research led me to form were as 

 follows : — 



1. That urobilin had been separated from urine. 



2. That by the treatment adopted it had been separated in combi- 

 nation with hydrochloric and sulphuric acid respectively. 



3. That the spectra of solutions of urobilin obtained by these 

 methods respectively differ in the position of certain feeble bands, but 

 agree in all possessing a black band at F, which can be made to disap- 

 pear by ammonia in excess, and which is replaced by another band 

 nearer the red end of the spectrum on the addition of sodic hydrate. 



4. Urobilin is an amorphous brownish-red pigment, which contains 

 carbon, oxygen, hydrogen and nitrogen. It is soluble in alcohol, 

 chloroform, acidulated water, and acids ; partially in ether, benzol, and 

 water, i.e., if the pigment be separated in combination with hydro- 

 chloric or sulphuric acid. 



5. Urobilin appears capable of existing in different states of oxida- 

 tion. 



6. It is derived from one of the colouring-matters of bile. 



7. It appears to be the colouring-matter of the bile of the mouse. 



