396 Dr. A. E. Gamxl. A Contribution to the Study [Apr. 2 



C. Tichborne* (1862) threw down most of the colouring mutter 

 a large quantity of concentrated urine upon a basic copper preci 

 tate, and extracted the pigment from the precipitate by means 

 cold dilute sulphuric acid and alcohol. 



In this way he obtained a solution which, on evaporation, left 

 brown residue, very hygroscopic and smelling of stale urine, soluti* 

 of which yielded, according to the degree of concentration, the vi 

 tints of normal urines. 



The pigment was soluble to almost any extent in water, was 

 soluble in ether, sparingly soluble in absolute alcohol, and m 

 readily in rectified spirit. It was precipitated from solution by 

 lead acetate. 



The results of elementary analysis led Tichborne to think that 

 was derived from hippnric acid by the subtraction of water, the 

 centage composition obtained being C, 67*80 ; H, 4'23 ; X, 8* 

 O, 19-41. 



It is extremely doubtful whether combustion analyses of such 

 stances are calculated to materially advance our knowledge, in 

 absence of any of the ordinary guarantees of the purity of the su 

 stance analysed ; and so simple a process as that employed by Tic 

 borne could only be expected to yield a product of a moderate degr 

 of purity. 



Thudichum| (1864) obtained from normal urine by a variety 

 processes a substance to which he gave the name of urocbrome, ai 

 his researches which have extended over a long period form the mo 

 elaborate contribution yet made to the subject. 



In the second edition of his work on the urine,J in which his 

 researches are embodied, he gives four methods for the isolation 

 urochrome in which phosphomolybdic acid and the neutral and 

 lead acetates are employed as precipitants, and sulphuric acid, sul 

 uretted hydrogen, &c., for the extraction of the pigment from the 

 cipitates. Great pains were taken to obtain the pigment in 

 highest attainable degree of purity. 



Thudichum describes urochrome as forming yellow crusts when 

 solutions are evaporated, as dissolving very readily in water, fi 

 readily in ether, and least easily in alcohol. It was precipitated 

 its solutions by lead acetate, silver nitrate, acetate and nitrate 

 mercury, &c. 



On heating with mineral acids the aqueous solution became 

 and resinous flakes were thrown down from which three defi 

 substances could be obtained, which were minutely studied, and 

 jected to ultimate analysis. These substances were a red pignu 



* ' Chemical News,' 18G2, vol. 5, p. 171. 



t Loc. cit. 



J ' Pathology of the Urine,' 2nd Edit,, 1877, p. 217. 



