426 SKATOL. SKATOL-CARBONIC ACID. [BOOK II. 



unchanged into the distillate, whereas the picric acid compound of 

 indol when similarly treated does not furnish indol, in consequence 

 of the latter being decomposed. 



Characteristic Skatol is recognised by its crystalline form, its 

 reactions. fgecal odour, and its melting point, and by the following 



reactions : 



1. It does not like indol, which it closely resembles, give a 

 red colouration, or precipitate, with nitric acid, containing nitrous acid, 

 but only a milky- white turbidity, which is perceptible in a solution 

 containing 1 part of skatol in 10,000 of water (Salkowski). 



2. It dissolves in concentrated hydrochloric acid, the solution 

 possessing a violet colour. 



3. When a solution of skatol is treated with a solution of sodium 

 nitro-prusside and then solution of caustic soda is added, an intense 

 yellow colour appears. On now adding one-fourth of its volume of 

 glacial acetic acid and boiling for some minutes the solution gradually 

 becomes violet. The intensity of the colouration, which is not great, 

 increases with time. When shaken with acetic ether, the colouring 

 matter is taken up by it (Salkowski 1 ). 



4. When skatol is dissolved in benzol and the solution is treated 

 with a solution of picric acid in benzol, the red picric acid compound 

 separates. When distilled with caustic soda, this yields skatol 

 unchanged (vide supra). 



Fate and Skatol is in great part excreted in the faeces ; some 



transfonna- i Sj however, absorbed, oxidised, and excreted in the 

 tions of skatol urine ag one of the so _ ca u e( j ethereal sulphates ska- 

 in the economy. , , i i -\ / ^n\ 



toxyl-sulphunc acid (compare p. 169). 



.C.CH 3 = C.COOH 

 3. a-Skatolcarbonic acid, C 10 H 9 N0 2 = C 6 H 4 



IE. 



In addition to indol and skatol, E. and H. Salkowski discovered, 

 amongst the constant products of the putrefaction of proteids, a body 

 which is closely related to the two former, and to which they gave 

 the name of skatolcarbonic acid 2 , a name justified by the fact that it 

 may be artificially produced by heating methyl-indol 3 and metallic 

 sodium in a current of C0 2 . 



Mode of se- The method of preparation of skatol- carbonic acid 

 paration. which, unlike indol and skatol, is non-volatile, is so 



1 Salkowski, op. cit. Zeitsch.f.phys. Chemie, Vol. vm. (188384), p. 448. 



2 E. Salkowski, 'Zur Kenntniss der Eiweissfaulniss, II.: Die Skatolcarbonsaure, 

 nach gemeinschaftlich mit H. Salkowski in Minister i. W. angestellten Versuchen,' 

 Zeitschr. f. phys. Chemie, Vol. ix. (1885), pp. 8 33. 



3 Ciamician and Magnanini, 'Ueber die Carbonsauren der Methylindole,' Ber. d. 

 deutsch. chem. Gesell. Vol. xxi. (1888), p. 1925. 



