THE PIGMENTS OF THE URINE. 297 



solution of sodium carbonate, and are then precipitated by adding 

 an excess of sulphuric acid. By redissolution in a dilute solution 

 of sodium hydrate and reprecipitation with acetic acid they can be 

 obtained in comparatively pure form. But it will be noted that a 

 certain fraction remains in the acetic acid solution, which indicates 

 the existence of at least two different pigments. The soluble 

 form has been termed phymatorliusin, and, according to Nencki 

 and Sieber, contains no iron, while Morner claims that this is 

 present. Elementary analysis of this pigment has given the fol- 

 lowing results (Morner) : 



From growth. From urine. 



Carbon 55.32 to 56.13 per cent. 55.76 per cent. 



Hydrogen . 5.65 to 6.33 " " 5.95 " 



Nitrogen 12.30 " " 12.27 " " 



Sulphur 7.97 " " 9.01 " " 



Iron . 0.063 to 0.081 " " 0.20 " " 



From melanotic growths in horses a hippomelanin has been 

 obtained, which, in contradistinction to the first, is soluble in solu- 

 tions of the alkalies with difficulty. 



The Bile -pigments. Bile-pigments are never found in the 

 urine under normal conditions. As a rule, freshly voided urine 

 contains only bilirubin. If a complicating cystitis, however, exists, 

 the common derivatives of bilirubin, viz., biliverdin, bilifuscin, 

 biliprasin, and bilihumin, may also be encountered. 



Bile-containing urines present a very characteristic color, which 

 may vary from a bright golden-yellow to a greenish brown, and on 

 microscopical examination it is common to find the morphological 

 elements stained an intense yellow. This color is further imparted 

 to the foam on shaking. But as urobilin when present in large 

 amounts may impart a similar color to the urine, it is always 

 better to resort to chemical tests. These have been described in 

 detail in the section on the Bile, and are directly applicable also to 

 the urine (see page 158). 



Other pigments also may occur in the urine after the ingestion of 

 various drugs, but as the products thus formed are of no special 

 interest from the standpoint of animal chemistry, they are not con- 

 sidered at this place. 



The Bile-acids. The occurrence of bile-acids in the urine is 

 solely a pathological phenomenon. In normal urines they are never 

 found, and even in complete obstruction of the common duct their 

 amount is quite small. To demonstrate their presence, they must 

 first be isolated as Platner's bile, and can then be identified by 

 polarimetric examination, their action upon the frog's heart, etc. 

 (see pages 147 and 148). 



