30 



Dr. C. A. MacMunn. Researches into the 



line stood at the same number on the scale. Of course this would 

 have been unnecessary if the jaws of the slit had been made to open 

 equally. 



The readings are also given in wave-lengths, the latter having been 

 calculated by means of an interpolation curve ; they are expressed in 

 millionths of a millimetre. 



Since preliminary observation had shown that there are two pig- 

 ments in urine which give a band at F, it was necessary, if possible, 

 to get a specimen of urine which contained urobilin only. Accordingly, 

 the urine of a case of phthisis was chosen, which gave the band at F, 

 in very slight depths ; this band could be made to disappear by 

 ammonia, and was moved towards the red by caustic soda. The 

 colour of the urine was orange-red. The urine therefore contained 

 urobilin, and on six different occasions I separated urobilin by the 

 following method from it ; on each occasion the result was the same. 

 I may mention that no play of colours was produced by nitric acid 

 (containing nitrous.) 



Experiments. — 230 cub. centims. of urine was precipitated by 

 neutral lead acetate, and filtered, the filtrate which still showed the 

 urobilin band was precipitated with basic lead acetate and filtered ; 

 the filtrate now showed no band. The precipitates were united and 

 extracted with alcohol acidulated with sulphuric acid, and again 

 thrown on a filter. The filtrate was a fine, clear red fluid giving in 

 slight depths a well-marked black band at F. Some of this fluid was 

 put into a separating funnel, a large quantity of water added, and then 

 chloroform ; the whole well shaken and allowed to stand, the red 

 chloroform layer separated off and examined, when it was seen to give 

 the same black band. The remainder of the alcoholic fluid was treated 

 in the same manner. I had now a fine red fluid, being a solution of 

 urobilin in chloroform, with, however, a little turbidity at its surface, 

 which disappeared after filtration, which was twice repeated. 



An attempt was made to separate some of the colouring matter from 

 the chloroform with acidulated water, but with a negative result. 



The chloroform was now distilled off, the residue redissolved in 

 chloroform, which was again distilled off (in both cases over a water- 

 bath). The residue was brown-red in colour, glistening on the surface, 

 perfectly amorphous, and gave, when examined on the stage of the 

 micro-spectroscope, with a strong light condensed upon its surface, a 

 black band at F. It is perfectly soluble in alcohol, chloroform, nitric 

 acid, hydrochloric acid, acetic acid, lactic acid, acidulated water, 

 partially in ether, both ethereal solution and residue when dissolved 

 in alcohol, giving same spectrum ; partially in benzol and in water ; 

 insoluble in bisulphide of carbon. 



The chloroformic solution gives no precipitate with chloride of 

 "barium, nor after treatment with ammonia. 



