PUTREFACTION PRODUCTS OF PROTEIDS. 173 



8. Hydroparacumaric Acid, Paroxyphenyl-propionic Acid, 



C H4 \CH 2 CH 2 C0 2 H (p) 



This substance is very similar in its properties to the pre- 

 vious acid, but is more readily soluble in water and in ben- 

 zene. Melting-point 127. According to Baumann it also 

 occurs in the urine, together with paroxyphenyl-acetic acid. 



9. Skatol-carbonic Acid, C 9 H 8 N.COOH. 



Skatol-carbonic acid crystallizes in leaflets which are 

 readily soluble in alcohol and ether, less in hot water, still 

 less in cold water, and difficultly in benzene. Melting-point 

 164. When heated beyond its melting-point it decomposes 

 into skatol and carbon dioxide. When introduced into the 

 organism it is excreted unchanged. 



REACTIONS OF THE AQUEOUS SOLUTION (1 : 1000). l 



(a) If a few drops of pure nitric acid of 1.2 specific gravity 

 be added to the solution and then some drops of a 2 per cent, 

 solution of potassium nitrite, it turns cherry-red after a time, 

 then becomes turbid, depositing a red coloring matter which 

 is not identical with the nitrosoindol nitrate. 



(6) If an equal volume of hydrochloric acid (of 1.12 

 sp. gr.) be added to the solution and then a few drops of a 

 weak (1-2 per cent.) solution of chloride of lime, it gradually 

 turns purple-red and deposits a purple-red precipitate. 



(c) If some drops of hydrochloric acid and a few drops of 

 very dilute ferric chloride are added to the solution and the 

 mixture heated, it turns cherry-red even before the tempera- 

 ture reaches the boiling-point. 



1 Zeitschr. f. physiol. Chemie, 9, 24. 



