222 THE FECES. 



rated from each other according to usual analytical methods. Dis- 

 tillate C is now rendered alkaline with sodium hydrate and ex- 

 tracted with ether by shaking. This takes up the indol and skatol, 

 which may be obtained in crystalline form on evaporation of the 

 ether, and can be separated from each other by fractional distillation 

 with steam, when the skatol passes into the distillate first. The 

 residual solution of C contains phenol and paracresol as sodium 

 compounds. This is now acidified with sulphuric acid and distilled, 

 when the phenols pass over, and may then be separated from each 

 other as described elsewhere. 



The residual solution A is now concentrated and treated with a 

 large excess of alcohol, in order to precipitate any albumins and 

 mineral salts that may be present. The alcoholic filtrate is then 

 transformed into an aqueous solution and acidified with sulphuric 

 acid. The aromatic acids are thus set free and are extracted with 

 ether by shaking. The ethereal solution is evaporated to dryness, 

 the residue dissolved in a small amount of a dilute solution of 

 sodium hydrate, and precipitated with barium chloride. The fatty 

 acids are thus obtained as barium soaps, and are filtered off. They 

 are placed in water, which dissolves the salts of the aromatic acids. 

 In this solution the acids are then set free by acidifying with sul- 

 phuric acid, and are extracted with ether. The ethereal extract is 

 now evaporated to dryness and the free acids dissolved in water. 

 On distillation in a current of steam, phenyl-propionic acid and 

 phenyl-acetic acid pass over, and can be subsequently separated 

 from each other by fractional distillation. The hydroxylated oxy- 

 acids and skatol-carbonic acid remain behind. The latter separates 

 out, on further concentration of the solution and cooling, in the 

 form of white wart-like granules, while the oxy-acids remain behind, 

 and can be separated from each other by means of their varying 

 solubility in benzol. They can be recognized by applying Millon's 

 test. Skatol-carbonic acid, on the other hand, reacts in very much 

 the same manner with yellow nitric acid as does indol, but the red 

 color is in this case referable to a different pigment (see also page 

 273). 



Hydrobilirubin. It has been stated that bilirubin under the 

 influence of bacterial action supposedly undergoes a process of reduc- 

 tion in the intestinal canal and is transformed into hydrobilirubin. 

 It is assumed that as such it is then in part absorbed and possibly 

 appears in the urine, while the remaining portion is eliminated in 

 the feces. According to some observers, it is identical with the 

 stercobilin of Yanlair and Masius. The spectrum of the two bodies 

 is very similar, but while solutions of hydrobilirubin on treatment 

 with chloride of zinc and ammonia show three bands of absorption, 

 stercobilin is said to give rise to four bands. Garrod claims that 

 stercobilin is identical with the urobilin of the urine, and differs from 

 hydrobilirubin in containing a much smaller percentage of nitrogen, 

 viz., 4.11, as compared with 9.22. According to the same observer, 



