8 6 BA CTER10LOG Y. 



sity and rapidity of the reaction become greater under 

 the influence of heat, so in the process of disinfection 

 the combination between the disinfectant and the organ- 

 isms to be destroyed is much more energetic at a tem- 

 perature of 37 to 39 C. than it is at 12 to 15 C. 



A number of important and novel suggestions with 

 regard to the modus operandi of disinfection were 

 brought out through the work of Kronig and Paul, 1 

 who took up the subject from its physico-chemical 

 standpoint. The comprehensive nature of this elab- 

 orate investigation precludes more than a brief men- 

 tion of some of the conclusions reached, and in order 

 that these may be intelligible, certain beliefs (working 

 hypotheses) of the physical chemists should be borne in 

 mind. In 1887 Arrhenius proposed the theory that 

 when an electrolyte (a compound decomposable by an 

 electric current) is dissolved in water its molecules break 

 down, not simply into their component atoms, but into 

 ions, which are atoms or groups of atoms 'having electro- 

 positive and electro-negative characteristics. According 

 to this theory, salts, when dissolved in water, undergo 

 electrolytic dissociation into metallic and acidic ions, 

 the former being the electro-positive cation, the latter 

 the electro-negative anion ; sodium chloride, for exam- 

 ple, resolving itself, under these conditions, into its 

 sodium, or metal-ion, and its chlorine, or acidic ion. 

 The electro-positive cations, according to Ostwald, com- 

 prise the metals and metal-like radicals, such as am- 

 monium (NH 4 ) and hydrogen (H) ; while the electro- 

 negative anions include the halogens, the acidic radicals 

 (such asNO 3 and SO 4 ), and hydroxyl. 1 Using this theory 



i KrOnig arid Paul : Zeitschrift fur Hygiene und Infectionskrank- 

 heiten, 187, vol. xxv. pp. 1-112. 



