158 BACTERIAL POISONS. 



Oue of the first thiugs for the chemist who undertakes 

 to do this work is to ascertain whether or not his reagents 

 are pure. We have found a number of samples of German 

 ether, which was imported on account of its supposed 

 purity, to yield on spontaneous evaporation a residue which 

 gave several of the alkaloidal reactions, and a few drops of 

 which, injected under the skin of a frog, caused paralysis 

 and death within a few minutes. We would advise that 500 

 c.c. of the ether to be used should be allowed to evaporate 

 spontaneously, aud its residue, if there be one, be examined 

 both chemically aud physiologically. The basic substance 

 which exists in some samples of sulphuric ether is pyridine. 



GuAEESCHi and Mosso found commercial alcohol almost 

 invariably to contain small quantities of an alkaloidal sub- 

 stance, the odor of which is similar to that of nicotine and 

 pyridine. Its solutions are precipitated by gold chloride, 

 phosphowolframic acid, phosphomolybdic acid, potassium 

 iodide, and Mayer's reagent, but not by platinum chloride 

 or tannic acid. It does not reduce, or reduces feebly, ferric 

 salts. From one sample of alcohol they obtained a base 

 which, in addition to the above reactions, did give a pre- 

 cipitate with platinum chloride. Alcohol may be freed 

 from these substances by distillation over tartaric acid. 



In amylic alcohol, Haitinger has found as much as 

 0.5 per cent, of pyridine. It may be purified in the same 

 manner as recommended for ethylic alcohol. 



Chloroform, wlien found to leave any residue on evapora- 

 tion, should be washed first with distilled water, then with 

 distilled water rendered alkaline with potassium carbonate, 

 then dried over calcium chloride and distilled. 



Petroleum ether sometimes contains a base which has an 

 odor similar to trimethylamine or pyridine, and which gives 

 a precipitate with platinum chloride, forming in octahedra. 



Benzole may contain a similar substance. 



The following methods have been used for the purpose 

 of extracting the putrefactive alkaloids : 



The Stas Otto Method. — This method depends upon 

 the following facts : (1) The salts of the alkaloids are sol- 



