100 COLORING MATTERS. 



chum, 1 and called by him urochrome, is precipitable from the urine by 

 various metallic salts. It has not yet been produced in a crystalline 

 form. It is soluble in water and in ether, but only slightly soluble 

 in alcohol. Its watery solution has a yellowish color, which, on stand- 

 ing, becomes red. Urohematine (Harley) is nitrogenous in composition, 

 and contains iron. 2 It is insoluble in pure water, but soluble in the 

 fresh urine, as well as in ether, chloroform, and alcohol. The sub- 

 stance termed Urobiline (Jaffe) was so named because supposed to be 

 derived from the coloring matters of the bile. It is soluble in alcohol, 

 ether, and chloroform. Its solutions have a brownish-yellow color, 

 and, by dilution, become first yellow, and lastly faint rosy-red. It was 

 found by Jaffe 5 to be present in nearly every instance (45 cases) in 

 healthy human urine, where it was recognized, after partial extraction 

 and purification, by its peculiar optical (spectroscopic) properties. 

 The same observer, however, found that fresh urine, not subjected to 

 chemical manipulation, would often present no indication of urobiline. 

 Such urine, if secluded from the atmosphere, would remain light- 

 colored, and free from this substance ; but if exposed to the air for from 

 two to twelve hours, would become darker in hue, and at the same time 

 would show, by the spectroscope, signs of the presence of urobiline. 



It is evident, therefore, that the urine contains a coloring matter 

 which gives to it in the fresh condition its well known amber tint. 

 This substance is liable to be changed under the influence of oxidation, 

 and to assume in that condition a more or less distinct red color. 

 Such a modification certainly takes place outside the body, and it is 

 possible that it may also occur within the system, giving rise to the 

 varying proportions of red in the color of the urine in different 

 healthy and diseased conditions. 



Beside the above named substances, there are two other bodies of suf- 

 ficient interest in general physiology to be enumerated in connection 

 with those already described. 



Lnteine. 



This substance, as its name indicates, is of a strongly marked yellow 

 color. It is extracted from the yolk of eggs, and from the tissue of the 

 corpus luteum. It exists also, according to Thudichum, 4 in the grains 

 of Indian corn, in certain berries and roots, and in the yellow stamens 

 and petals of a large number of flowering plants. It is crystallizable, 

 soluble in alcohol, ether, .chloroform, and the fatty oils, but insoluble in 

 water. It is readily decomposed and decolorized by sunshine ; and by 

 the action of nitric acid it is first turned blue, and afterward decolorized. 



1 British Medical Journal, London, Nov. 5, 1864. 



2 Harley, The Urine and its Derangements. Philadelphia, 1872, p. 97. 



3 Archiv fur Pathologische Anatomic und Physiologic, 1869, vol. xlvii. 

 p. 405. 



4 Centralblatt fur'die'Me.lictnische W'hsFfosch'afttfn', 78f&; JK 2. 



