REMARKS UPON THE METHODS. 165 



the fatty acids continue to separate. The liquid is then 

 warmed and distilled as long as a turbid fluid passes over. 

 Pyrrol, skatol, phenol, indol, volatile fatty acids, and some 

 of the ammonia pass over. The portion which remains in 

 the retort is rendered alkaline with lime-water. The pre- 

 cipitate which forms, and which contains the greater part 

 of the fixed fatty acids, is removed. The liquid portion, 

 which is alkaline, is distilled to dryness, care being taken 

 to receive the distillate in very dilute sulphuric acid. The 

 bases and ammonia pass over. The distillate is neutralized 

 (with sulphuric acid) and evaporated almost to dryness, 

 then decanted from ammonium sulphate, which crystallizes. 

 The mother-liquor is extracted with concentrated alcohol, 

 which dissolves the sulphates of the ptomaines. After 

 driving off the alcohol, the residue is rendered alkaline 

 with caustic soda, and successively extracted with ether, 

 petroleum ether, and chloroform. 



The lime precipitate is dried and extracted with ether 

 of thirty-six degrees, which removes any fixed bases that 

 may be present. 



Remarks upon the Methods. — The fundamental 

 difference between the Stas-Otto and the Dragendoeff 

 methods consists in the fact that in the former the first 

 extraction is made with a dilute solution of an organic acid 

 (tartaric usually), while in the second a similar solution of 

 a mineral acid (sulphuric) is employed. In their various 

 modified forms any solvent may be used for separating the 

 alkaloid from the other constituents of the original solu- 

 tion. Therefore, the question has been asked. Which is 

 the more suitable acid for use in making the first solution? 

 The answer to this question will also be the one to the 

 question. Which is the better method of extracting pto- 

 maines, the Stas-Oto) method or that of Dragendorff? 

 The Italian chemists Guareschi and Mosso have at- 

 tempted to answer this question experimentally, and the 

 evidence which they have furnished is condemnatory of 

 the method of Dragendorff. They show that basic 

 bodies are formed by the action of the dilute sulphuric 



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