422 INDOL. [BOOK n. 



indol distils over. The distillate is again shaken with ether, the 

 ethereal solution distilled at the lowest possible temperature, and the 

 residue is evaporated in a deep flask until, on being allowed to cool, 

 the residue sets as a crystalline mass. The latter is then dried in an 

 exsiccator over sulphuric acid. It may be purified from skatol by 

 recrystallising from water. The yield of indol, by the process described, 

 amounts to about 6*5 parts per 1000 parts of water-free fibrin, or, 

 using the quantity of pressed, but yet moist, fibrin recommended, 

 the amount obtained is about 3 grammes. 



It was previously stated that, according to Baumann, indol and 

 skatol are not directly split off from the proteid molecule but are 

 products of decomposition of an intermediate substance. E. and H. 

 Salkowski have specially studied this matter in reference to indol 

 and, as a result of their experiments, have arrived at the following 

 conclusion in reference to indol : " That in the putrefaction of albumin, 

 indol is not immediately liberated from the albumin in a free con- 

 dition, but that an intermediate product is formed, which is gradually 

 decomposed by the further action of bacteria. This intermediate 

 product is still unknown ; it is not, however, peptone, the quantity of 

 which is (throughout the process of preparation) small, and in the 

 later stages seems entirely to disappear 1 ." 



Alleged dls- According to Odermatt 2 , Nencki 3 , and Brieger 4 , if 

 appearance of putrefaction be long continued, the quantity of indol 

 indol as a result gradually diminishes. Thus, in an experiment which 

 putrefaction 6 * 1 ^ aste( ^ ^ ve months, Nencki found that the products of 

 putrefaction contained no indol s but only skatol, whilst 

 Brieger, in the products of putrefaction of liver, found no indol after 

 a lapse of only eleven days. Salkowski 5 has, however, come to the 

 conclusion that indol is not destroyed by the long continuance of 

 'putrefaction, and that its non-discovery in the above experiments is 

 to be explained by the fact that they were conducted in open vessels 

 and that the substance had disappeared through evaporation. 

 Physical and Indol crystallises from hot aqueous solutions in the 



form of small scales, the melting point of which is 

 52 C., and the boiling point 245 246 C. Indol, how- 

 ever, partly decomposes when heated to its boiling point, so that it is 

 advisable to distil it, as recommended in the directions for its 

 preparation, in a current of steam. The vapour of indol possesses a 



1 E. Salkowski, <Zur Kenntniss der Eiweissfaulniss, 1: Ueber die Bildung des 

 Indols und Skatols, nach gemeinschaftlich mit H. Salkowski in Minister angestellten 

 Versuchen,' Zeitschrift f. physiol. Chemie, Vol. vin. (18834), pp. 417 466. Kefer to 

 Sect. vii. 'Ueber den Modus der Entstehung des Indols aus dem Eiweiss,' op. cit. 

 pp. 454457. 



2 Odermatt, ' Zur Kenntniss der Phenolbildung bei der Faulniss der Eiweisskorper,' 

 Journ. f. prakt. Chemie, Vol. xvm. (1878). p. 249. 



3 Nencki, op. cit. Centralb. /. d. med. Wiss. 1878, No. 47. 



4 Brieger, 'Ueber die aromatischen Produkte aus Eiweiss,' Zeitschr.f. phys. Chemie, 

 Vol. m. (1879), p. 134 et seq. ; see p. 139. 



5 Salkowski, op. cit. Zeitsch. f. phys. Chem. p. 557 et seq. 



