In this way pyrrol, skatol, phenol, indol, and volatile fatty acids are separated and will be found in the distillate. The residue in the retort is treated with lime, filtered from the precipitate that forms, and distilled in a vacuum, the distillate being received in weak sulphuric acid. The bases accompanied with ammonia distil over. The distillate is now neutralised by sulphuric acid[654] and evaporated nearly to dryness, separating the mother liquid from sulphate of ammonia, which crystallises out. The mother liquids are treated with absolute alcohol, which dissolves the sulphates of the ptomaines. The alcohol is got rid of by evaporation, the residue treated with caustic soda, and the bases shaken out by successive treatment with ether, petroleum ether, and chloroform. The residue remaining in the retort with the excess of lime is dried, powdered, and exhausted with ether; the ethereal extract is separated, evaporated to dryness, the dry residue taken up in a little water, slightly acidulated, and the bases precipitated by an alkali.
[654] The first acid apparently is so dilute that the distillate more than neutralises it, hence more sulphuric acid is added to complete neutralisation.
§ 650. Brieger’s Process.—Brieger[655] thus describes his process:—
[655] Untersuchungen über Ptomaine, Theil iii., Berlin, 1886.
“The matters are finely divided and boiled with water feebly acidulated with hydrochloric acid.