92 CHEMICAL COMPONENTS OF THE HUMAN BODY. 



the nerve-vesicles, which may itself be derived from the blood-corpuscles, 31) ; 

 but that this pigment may be very easily decomposed into two substances, dif- 

 fering in their respective amounts of carbon and hydrogen. One of these, 

 termed by Heller uro-glaucin, forms a dark blue powder, which, when dried, 

 possesses a coppery lustre and dissolves in alcohol with a splendid purple color. 

 The other coloring substance, which may be generated by the action of hydro- 

 chloric and other acids upon the ordinary urine-pigment, is of a yellowish pink 

 hue when dissolved in alcohol, and specially attaches itself to the uric-acid salts, 

 which, when they are deposited from the urine, carry it down with them, just 

 as alumina carries down the coloring matter of cochineal ; this substance (the 

 uro-erythrine of Simon, the ur-rhodin of Heller) was long since termed purpu- 

 rine 1 by Dr. Gr. Bird, and by this name it may be most conveniently designated. 

 The urine-pigment as a whole is remarkable for the large proportion of carbon, 

 58 per cent., which it contains; in the purpurine generated by the action of 

 hydrochloric acid on urine, the proportion of carbon is 62 per cent.; but in 

 the urine of patients suffering under febrile disorders or organic disease of the 

 liver, in which a very large amount of purpurine exists, and in which bile-pig- 

 ment (a still more highly carbonized substance, 70) is very commonly present 

 likewise, the proportion of carbon has been found to rise even to 65f per cent. 

 The pathological conditions under which the amount of this carbonaceous pig- 

 ment increases, are such as to indicate that the elimination of carbon by the 

 liver, lungs, and skin is not being performed with its due activity ; and the 

 superfluity is thus thrown upon the kidneys for excretion. 3 There seems no 

 doubt that even normal Urine contains Sulphur in an unoxidized state ; and 

 the inquiries of Prof. Ronalds have led him to the conclusion that this element, 

 together with a small quantity of Phosphorus, is contained in a peculiar com- 

 pound which forms part of the so-called " extractive." This compound has not 

 yet been obtained in a separate form; but it furnishes the medium for the eli- 

 mination of from at least 3 to 5 grains of sulphur in the twenty-four hours. 

 The sulphur and phosphorus set free by the disintegration of the albuminous 

 tissues, are for the most part oxidated in the system, and carried out of it in the 

 form of sulphuric and phosphoric acids, in union with bases. But, as we shall 

 hereafter see ( 69), a provision exists in the biliary excretion, for carrying off 

 a large amount of sulphur in an unoxidized state; and it would appear as if the 

 urine became the vehicle for whatever unoxidized sulphur may remain to be 

 eliminated. The normal presence of this sulphur-extractive in the urine has 

 an interesting relation to the occasional or abnormal occurrence of the highly 

 sulphurized substance known as Cystine ( 66). 



65. Among the organic compounds whose occurrence in Human urine is 

 abnormal, we may first mention Xanihine, or Uric oxide, which is a very rare 

 constituent of calculi and of sedimentary deposits. This seems to be a neutral 

 substance, having no action on vegetable colors, and not being yet known to 

 enter into combination with either acids or alkalies. When freshly precipitated, 

 it presents itself as a white powder, which is neither crystalline nor gelatinous; 

 and, when dried, it forms pale, yellowish, hard masses, which, on being rubbed, 

 assume a waxy brightness. The calculi composed of this substance closely 

 resemble those formed of uric acid, for which they are generally mistaken ; they 

 may be distinguished, however, by the well-marked salmon or rather cinnamon 

 tint presented by their sections, and by the insolubility of their substance in a 



1 It is important to bear in mind that this substance has no relation whatever to murex- 

 ide ( 55), which was termed purpurate of ammonia by Dr. Prout, under the influence of an 

 erroneous view of its constitution. 



2 See Dr. Golding Bird's "Urinary Deposits," pp. 146-148, Am. Ed., and CHAP. xn. 

 SECT. 3, of the present volume. 



