82 BACTERIOLOGY. 



reached the following conclusions with regard to the 

 action of chemical disinfectants : 



The germicidal value of a metallic salt depends not 

 only upon its specific character, but also upon that of its 

 anion. 



Solutions of metallic salts in which the metallic part 

 is represented by a complex ion and in which the con- 

 centration of the metal ion is very slight, have but 

 feeble disinfecting activity. 



The halogen compounds of mercury act according to 

 the degree of their dissociation. 



The disinfecting power of the halogens — chlorine, 

 bromine, iodine — (as well as their compounds) is in in- 

 verse ratio to their atomic weights. 



The disinfecting activity of watery solutions of mer- 

 curic chloride is diminished by the addition to them 

 of other halogen compounds of metals and of hydro- 

 chloric acid. It appears probable that this is due to 

 obstruction offered to electrolytic dissociation. 



The disinfecting activities of watery solutions of mer- 

 curic nitrate, mercuric sulphate, and mercuric acetate are 

 increased by the moderate addition of sodium chloride. 



In general, acids disinfect according to the degree 

 of their dissociation — i. e., according to the concentra- 

 tion of their hydrogen ions in the solution. 



The bases, potassium, sodium, lithium, and ammo- 

 nium hydroxide, disinfect according to the degree of 

 their dissociation — i. e., corresponding to the concen- 

 tration of their hydroxyl ions in the solution. 



The disinfecting activity of metallic salts is, in gen- 

 eral, less in albuminous fluids than in water. It is 

 probable that this is due to a diminution in the concen- 

 tration of metallic ions in the solution. 



