308 A MANUAL OF BACTERIOLOGY 



filtrate is distilled, when pyrrol, skatol, phenol, 

 indol, the volatile fatty acids, and a portion of the 

 ammonia, are driven off. Gautier then adds lime 

 (until alkaline) to the portion which has not been 

 distilled, separates the precipitate which forms and 

 which contains the greater portion of the fixed fatty 

 acids, and he then distils the alkaline liquor to 

 dryness in vacuo, taking care to condense the 

 vapours in weak sulphuric acid. The bases are 

 then distilled with ammonia. After the distillation 

 is completed, the distillate is neutralised, then 

 evaporated nearly to dryness, when ammonium 

 sulphate deposits in the crystalline condition. This 

 is separated and rejected. Concentrated alcohol is 

 now added to the mother liquor, which dissolves 

 the sulphates of the ptomaines. After evaporating 

 off the alcohol, a small quantity of caustic soda 

 solution is added. This solution is successively 

 treated with ether, petroleum ether, and chloroform 

 (i.e. three different extracts are obtained). As to 

 the product remaining in the retort with the excess 

 of lime which had served to separate the bases or 

 ptomaines, it is treated with ether at 36 C., which 

 dissolves the fixed bases. By the addition of a 

 small quantity of acidulated water, the bases are 

 separated from the ether, and are then easily pre- 

 cipitated by the addition of an alkali. (2) Briegers 

 method consists in boiling the putrefying material 

 with water and then filtering. The filtrate is pre- 

 cipitated with plumbic acetate. This precipitate is 

 filtered off a stream of sulphuretted hydrogen is 

 passed through the filtrate, and the lead sulphide 



