INDOL ACETIC ACID. 733 



skatol chromogen exists in human urine, and that the observations made 

 heretofore were due to a confusion of skatol red with indigo red or uroro- 

 sein. It cannot be disputed that derivatives of skatol sometimes occur in 

 human urine, and to prevent confusion with indigo red it musfr be borne 

 in mind that indigo red is soluble in chloroform as well as in ether, while 

 skatol red is insoluble in these solvents. On the contrary skatol red 

 is soluble in amyl alcohol, and this solution shows absorption bands close 

 to the line D between it and E, corresponding to X = 577-550 (PORCHER 

 and HERVIEUX x ). 



In regard to a confusion of skatol red for urorosein it must also be 

 remarked that urorosein may also be a skatol red. The chromogen of 

 urorosein, as HERTER has shown in a case, is identical with indol acetic 

 acid, which passes into skatol on splitting off carbon dioxide. According 

 to HERTER 2 urorosein is not identical with skatol red, although the 

 investigations of STAAL, GROSSER, PORCHER and HERVIEUX 3 indicate 

 that they are identical, and the last two investigators consider them 

 identical, because they both have the same spectrum and the same 

 chemical behavior. 



C.CH 2 COOH 



Indol Acetic Acid (skatol-carboxylic acid), Ci H 9 N0 2 , C 6 H 4 <^\CH 



NH 



This acid, whose occurrence in the urine was first shown by SALKOWSKI, is found 

 in the urine in special putrefactive processes in the intestine (HERTER) and in 

 various diseases, especially in cachectic conditions. This is of course dependent 

 upon the fact whether indol acetic acid is the actual chromogen of urorosein, and 

 also whether the experience obtained as to the occurrence of urorosein can be 

 applied to the indol acetic acid. According to WECHSELMANN 4 it occurs (more 

 correctly as urorosein) as traces in normal urine, abundantlyiin horse urine, and 

 in especially large quantities in cow urine. When introduced into the animal 

 body it appears unchanged in the urine. 



This acid crystallizes in leaves which melt at 165, and on strongly heating 

 it yields skatol with the splitting off of carbon dioxide. The solution, acidified 

 with hydrochloric acid, when treated with a little ferric chloride solution, becomes 

 cherry red on boiling. With some acid and a little nitrite as well as with hydro- 

 chloric acid and chloride of lime the solution becomes red, then cloudy, and a 

 red pigment precipitates. This pigment is soluble in amyl alcohol and gives the 

 above-mentioned absorption bands between D and E. This red pigment is 

 urorosein. 



Urorosein is the name given by NENCKI S to a red pigment which occurs in 

 the urine under the conditions mentioned under indol acetic acid. This pig- 



1 Zeitschr. f. physiol. Chem., 45. 



2 Journ. of biol. Chem., 4. 



3 Staal, Zeitschr. f. physiol. Chem., 46; Grosser, ibid., 44; Porcher and Hervieux, 

 ibid., 45; Compt. Rend., 138, and Journ. de Physiol., 7. 



4 Salkowski, Zeitschr. f. physiol. Chem., 9; Wechselmann, cited in Bioch. Centralbl., 

 5, 784. 



5 Nencki and Sieber, Journ. f. prakt. Chem., (N. F.), 26. 



