COLOURING MATTERS. 4o 



III. THE URINE. 



a. Uroerthyrin. In certain pathological conditions (espe- 

 cially in intermittent fevers) the urine possesses an intensely 

 red colour, and deposits a dark red precipitate. Proust, who 

 was the first that carefully examined this class of sediments, 

 discovered in them a peculiar acid, to which he gave the name 

 of rosacic acid. He subsequently found that this acid was 

 merely a compound of uric acid with a red colouring matter. 

 This red colouring matter has been observed by Landered in 

 the sweat from the axillary region of a girl with fever. 



In order to isolate this pigment, we must boil a sediment 

 of this nature in spirit, which will take up the colouring matter 

 and a little luic acid. This uric acid must be removed by con- 

 centration and cooling, and then b}^ evaporation to dryness, we 

 obtain uroerythrin. It yields a vividly scarlet powder, is devoid 

 of odour, possesses but little taste, and is tolerably soluble in 

 water and spirit : these solutions are faintly acid. 



b. The blue and black pigments that have been described 

 by various authors (Braconnot,' Spangenberg,^ Granier and 

 Delens,^ Marcet, Prout,* &c.) and have received the names of 

 cyanurin and melanurin, are not of sufficient importance to 

 require any observations. 



11. Bil'm. 



Bilin is the name given by Berzelius to the substance which 

 he considers as the principal and most important constituent 

 of the bile. 



The following is the most simple process for its exhibition :^ 

 Acidulate perfectly fresh filtered ox-gall with a few drops of 

 acetic acid, and precipitate it with neutral acetate of lead. The 

 bilifellinic acid, which still remains in solution, must then be 

 precipitated, as a plastery mass, by basic acetate of lead, and 

 the filtered or decanted liquid, in which there is usually a little 



' Ann. de Chem. et de Phys. t. xxix, p. 252. 



2 Schweigger's Journal, t. xlvii, p. 487. 



3 lb. t. xxiii, p. 262. 



'' Medico-Chirurgical Transactions of London, v. xii. 



^ Lehinann, Lehrhuch der Physiologischen Chcmie, t. i, p. 309. 



