76 BACTERIOLOGY. 



mercury, then, is to add a suitable quantity of 

 common salt to the coirosive sublimate. Those 

 compounds of mercury which, like the cyan- 

 ides, are not precipitated with alkalies because 

 they at once form double salts, require no 

 addition of salt. These facts were recognized 

 several decades ago and made use of in medi- 

 cine, but had altogether fallen into oblivion un- 

 til Liebreich and later Behring again brought 

 them to light. The double salt of mercuric 

 chloride and sodium chloride is precipitated by 

 the earthy alkalies, although not by the alka- 

 line carbonates, so that the solution should be 

 prepared with distilled water or with soft water. 

 Taking into consideration the matter of solu- 

 bility, gold and silver salts such as potassium 

 auri-cyanide and silver nitrate or. lunar caustic 

 are very powerful antiseptics. 



Pure carbolic acid or phenol (C 6 H 5 OH) is 

 soluble in water, but the crude carbolic acid 

 dissolves only with difficulty. For this reason 

 various means have been devised for making 

 the commercial acid soluble in water. Hueppe 

 found that if a solution was prepared with sul- 

 phuric acid the phenol sulfonic acids which arise 

 through the replacement by HSO 3 of an atom of 

 hydrogen in the phenol and which are readily 

 soluble in water act very energetically upon 

 bacteria. Under the name of aseptol they have 



