A contribution to the study of the yellow colouring matter of the urine / by Archibald E. Garrod ; [communicated by Sir Alfred B. Garrod].

  • Garrod, Archibald Edward, 1857-1936.
Date:
[1894]
Catalogue details

Licence: Public Domain Mark

Credit: A contribution to the study of the yellow colouring matter of the urine / by Archibald E. Garrod ; [communicated by Sir Alfred B. Garrod]. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    tions it was not possible to assign to it even an approximate limit. There was no increase of the absorption in the position of the urobilin band. Treatment with zinc chloride and ammonia did not produce any fluorescence. The alcoholic solutions always showed the same rich yellow or orange tint, and could be kept for a long time without undergoing any appreciable change ; but aqueous solutions kept in stoppered bottles tended to assume a brown tint on standing, even when dilute, and this change was precipitated by evaporation or warmth. In this respect my product behaved just like urochrome. The tendency of the aqueous solutions to undergo this change could be restrained by the addition of a little ammonia. Alkalies did not appreciably alter the tint of dilute solutions, but more concentrated ones were slightly browner when alkaline than in the neutral condition. Small additions of mineral acid produced no immediate change, but larger quantities quickly changed the colour to a reddish-brown. Solutions of the pigment were decolorised by nascent hydrogen produced by the action of hydrochloric acid upon zinc. This is only to be expected, seeing that it is a known fact that the urine is itself decolorised by similar treatment.* The destroyed colour was not restored by hydrogen peroxide. Action of Mineral Acids upon the Pigment. Solutions of the yellow pigment when warmed with nitric acid re- mained clear, but took a distinctly brighter yellow tint. On the addition of ammonia to alkalinity the yellow colour changed to a rich orange, the changes of tint being exactly similar to those which con- stitute the xanthoproteic reaction. This reaction seemed to be due to a change in the pigment as a whole, and not to any traces of impurity present. Heated over the water bath with the addition of sulphuric or hydrochloric acid, the changes observed were uniform with all speci- mens of the indigo-free pigment which were subjected to this treatment, and were the same whichever of the two acids was employed. The colour of the liquid quickly changed to reddish-brown, and on evaporation to dryness a nearly black residue was left. This residue, when treated with water, yields au orange-coloured solution, resem- bling the original liquid in colour, but darker in tint. This aqueous extract left on evaporation a brown residue, which was scarcely soluble in alcohol, but which communicated a yellow colour to chloroform. * Salkowski und Leube, ‘ Die Lehre vom Harn,’ 1882, p. 14.