PUTREFACTION PRODUCTS OF P ROTE IDS. 165 



hol, which leaves the ammonium chloride undissolved, and the 

 ammonium bases are precipitated with platinum chloride, etc. 



2. The indol obtained by evaporating the ether solution 

 (C) is still impure, containing especially phenol or cresol. In 

 order to remove these impurities, wash the mixture into a 

 flask with hot water, add sodium hydroxide solution, and dis- 

 til, preferably in a current of steam. The indol passes over 

 into the receiver, partly as a half-melted white mass, partly 

 in the form of leaflets and some deposits as a solid in the 

 condenser-tube. To remove the indol from this to the receiver 

 after all the indol has distilled, it is best to attach a flask con- 

 taining ether to the condenser in place of the distilling-flask 

 and gently warm it on the water-bath. The ether which 

 condenses in the condenser-tube dissolves the indol, and the 

 ethereal solution runs into the receiver; finally, the whole 

 of the indol is extracted from the distillate with ether, the 

 ether solution separated, and, after distilling off most of the 

 ether, allowed to evaporate spontaneously. The alkaline 

 fluid remaining in the distilling-flask is added to the alkaline 

 solution (D). 



Very frequently the indol thus obtained contains skatol. 

 To detect this substance, it is sufficient, when it is present in 

 any considerable quantity, to distil a portion of the indol 

 with water: the first drops of the distillate will contain prin- 

 cipally skatol in the form of leaflets with a mother-of-pearl 

 lustre, as the skatol is much more readily volatile with steam 

 than indol. 1 



3. The crude mixture of phenol and cresol obtained by 

 evaporating the ether solution (E) is also to be purified by 

 distillation in steam after it has been made alkaline with 

 sodium carbonate solution. A small portion of these sub- 

 stances is lost in this process. From the distillate the sub- 

 stances in question are again extracted with ether. 



1 Zeitschr. f . phys. Chemie, 8, 438. 



