44 BACTERIOLOGY. 



a filter and redissolved in distilled water. In another experiment 

 the albumose underwent a second precipitation, and after washing 

 was again dissolved. 



The alcoholic filtrate from the precipitated albuminous bodies was 

 then concentrated at a very gentle heat until a viscous residue was 

 left containing the glycerine originally present in the cultivating 

 medium and the extractives and products of the bacillus soluble 

 in alcohol. With this residue definite reactions of an alkaloidal 

 substance or ptomaine were obtained. 



Careful experiments, however, led to the belief that the whole 

 of the ptomaine was not separated from the albuminous precipitate 

 by simple addition of alcohol, and the above method was therefore 

 slightly modified. 



The ptomaine is soluble in water and alcohol, and sparinglj' 

 soluble in amyl-alcohol, but insoluble in benzine, ether, or chloro- 

 form, which liquids therefore fail to extract it from aqueous 

 solutions. In its aqueous solutions it is distinctly but not strongly 

 alkaline to test-paper. Phospho-tungstic acid gives with it a white 

 flocculent precipitate. Phospho-molybdio acid gives a pale yellow 

 precipitate, soluble in ammonia to a blue solution which becomes 

 colourless on boiling. In this respect it resembles the vegetable alka- 

 ' loids, aconitin and a'tropin. It must be remembered, however, that 

 albuminous bodies are precipitated by both this and the preceding 

 reagents, and in the case of the former a reduction of the phospho- 

 molybdate giving the blue solution with ammonia is obtained. 



The reducing power of the ptomaine is shown by the conversion 

 after a short time of ferri-cyanide of potassium to ferro-cyanide, 

 giving the Prussian blue test with ferric chloride, to which much 

 undue importance was attached by Brouardel and Boutmy. The 

 solution of albumose and sokition of peptone are both capable of 

 giving this reaction as well as many vegetable alkaloids. A solution 

 of the ptomaine is not precipitated by ferro-cyanide of potassium or 

 potassic bichromate. 



In strong solutions it yields precipitates with platinic chloride 

 (yellow), gold chloride (pale yellow), and mercuric chloride (white). 

 That yielded by the first of these reagents is granular in character, 

 and quite insoluble in alcohol, though apparently soluble in water. 

 The precipitation by gold chloride excludes amides and ammonium 

 salts. 



With iodine in hydriodic acid or potassic iodide a precipitate is 

 obtained which is occasionally crystalline, more often granular or 

 amorphous. 



