134 ATLAS OF BACTERIOLOGY. 



The isolation of these bodies can only be hinted at. 

 According to Brieger's method, which is usually 

 employed, the culture of a feebly acid reaction (hy- 

 drochloric acid) is brought to a boil for a short time, 

 the nitrate then condensed into a syrup, dissolved in 

 ninety-six-per-cent alcohol, and then freed from im- 

 purities (especially traces of albumin) by alcoholic 

 lead acetate. The lead is then removed, the filtrate 

 concentrated, and from this the mercurial binary 

 compound of the ptomains are precipitated with al- 

 coholic solution of corrosive sublimate. When the 

 alcohol has been removed by heat and the mercury 

 by sulphuretted hydrogen, the characteristic gold and 

 platinum binary compounds are produced, or we at- 

 tempt directly to obtain the crystalline chlorhydrates 

 and, by the aid of caustic soda, the free, often fluid, 



Some ptomains, like very many vegetable alka- 

 loids, can be easily obtained with ether in a watery 

 solution as soon as they have been set free by potash 

 lye. But Brieger's method is much better because it 

 secures many substances which do not dissolve in 

 ether. 



3. Formation of Complicated "Albumin-like" Toxic 

 Metabolic Products. 



("Toxalbumins," Toxins.) 



In connection with the discussion of the relatively 

 simple, basic, more or less poisonous metabolic prod- 

 ucts of bacteria, we may make a few brief remarks 

 on other bacterial poisons. In the present state of 

 our knowledge they may be divided into two classes. 



