THE PTOMAINES AND SOLUBLE FERMENTS 307 



(a) General properties of the Ptomaines. All the 

 ptomaines (cadaveric) are soluble in alcoholic ether. 

 Many of them dissolve in chloroform and amylic 

 alcohol. The general reagents which precipitate 

 the ptomaines are the following: Myer's and 

 Nessler's reagents, a solution of iodine in potassium 

 iodide, the iodide of bismuth and potassium, and 

 the phosphomolybdate of sodium. Mercuric chlo- 

 ride sometimes precipitates and sometimes does not 

 precipitate the ptomaines, but it generally forms 

 with them a double crystallisable chloride deposited 

 from boiling water. Auric chloride often gives a 

 yellow precipitate, soluble in water, or generally a 

 very soluble aurochloride, which rapidly dissolves. 

 Picric acid forms slightly soluble picrates. Tannin 

 produces insoluble, as well as very slightly soluble 

 tannates. Sulphuric acid diluted with a very small 

 quantity of water produces a red- violet colour with 

 the ptomaines. Hydrochloric acid gives a red- 

 violet colour, which heat develops. Platinic chlo- 

 ride generally forms crystallisable compounds with 

 the ptomaines. The majority of the ptomaines are 

 crystallisable compounds, although a few are liquids. 

 They are all, more or less, of a poisonous nature. 



(b) Extraction of the Ptomaines. The three most 

 important methods for extracting ptomaines from 

 putrefying and other material are those of Gautier, 

 Brieger, and Luff. (1) Gautier' s method consists in 

 adding oxalic acid to the warm liquor of bacterial 

 fermentation. By this means fatty or oily liquors 

 are liberated, and float on the surface of the liquor. 

 After separating the fats, the liquor is filtered. The 



