220 Dr. C. A. MacMunn. Researches into the [Dec. 16, 



half hours it was yellow in colour, and minute particles of a brownish 

 substance were seen suspended in it. This yellow fluid gave a band, 8, 

 from wave-length 513 to 488. It was then treated with hydrochloric 

 acid, until acid in reaction, when it became reddish-brown. It was 

 then filtered as brownish particles became separated by the action of the 

 hydrochloric acid. The filtrate was a beautiful red colour, and gave 

 a black band, <x, 507 to 480 ; another reading in a thinner layer gave 

 wave-length 501 to 482. When caustic soda was added to alkalinity 

 another band, intensity c, appeared from wave-length 513 to 486, the 

 solution at the same time getting yellow in colour. 



The insoluble portions in the filter were a dirty green-brown colour, 

 and gave, when dissolved in alcohol, an olive-coloured solution. In 

 deep layers of this alcoholic solution there were seen two bands near 

 D, the darker before D, the lighter on its violet side, and in shallow 

 layers a dark band, a, was seen at F. (See Chart II, sp. 12 and 13.) 

 Treated with caustic soda sp. 14 appeared. I may here mention that 

 these same bands appear when the alcoholic extract of human bile- 

 pigment is treated with caustic soda, and in gall-stones (as before 

 referred to), sp. 3. It would therefore appear, that in addition to a 

 body more closely resembling febrile urobilin, which the fluid con- 

 tained, an insoluble body was separated which appears to be identical 

 with that kind of urobilin which occurs in bile and in gall-stones. 



Action of Caustic Soda and Hydro chloric Acid on Bilirubin. — As there 

 is reason to believe that caustic soda alone changes bilirubin, and that 

 hydrochloric acid oxidises it, I thought it would be interesting to 

 compare the action of these reagents with that of the sodium 

 amalgam. And in order to compare the action of the caustic soda, 

 under the same circumstances as those which may be supposed to 

 occur when sodium amalgam is used, I used a solid piece of pure 

 caustic soda. When a solid piece of caustic soda is thrown into* 

 water in which bilirubin is suspended, the fluid becomes orange, 

 showing where it touches the dish a reddish tinge. (After five 

 minutes' action if a little of the fluid be taken out and treated with 

 hydrochloric acid it becomes green in colour.) At the end of twenty 

 minutes the fluid becomes green. If another piece of solid caustic 

 soda be now put in and the fluid examined twenty-three hours after 

 the commencement of the experiment, it is found to be a pale yellow- 

 green colour, showing only general absorption of the violet end 

 of the spectrum. When hydrochloric acid is added it turns red, 

 quickly changing to brown, and giving before the spectroscope a black 

 band, a, wave-length 507 to 482, and a feeble one, £, 625 to 598. 

 When this brown fluid is treated with caustic soda a shading appears 

 over the violet end beginning at 516. It would therefore appear that 

 the action of the caustic soda and subsequently hydrochloric acid is to 

 oxidise the pigment just beyond the stage of febrile urobilin, and 



