CHEMICAL STERILIZATION AND DISINFECTION. 81 



A number of important and novel suggestions with 

 regard to the modus operandi of disinfection have re- 

 cently been brought out through the work of Kronig 

 and Paul/ who took up the subject from its physical- 

 chemical standpoint. The comprehensive nature of this 

 elaborate 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 (NH4) and hydrogen (H) ; while the electro- 

 negative anions include the halogens, the acidic radicals 

 (such as NO3 and SO^), and hydroxyl.^ Using this theory 

 as the basis of their investigations, Kronig and Paul 



' Kronig and Paul ; Zeitschrift fiir Hygiene und Infectionskrank- 

 heiten, 1897, Band xxv. S. 1-112. 



^ Consult Ostwald's Lehrbuch der Allg. Chemie ; or Muix's transla- 

 tion of Ostwald's Solutions, p. 189, published by Longmans, Green & 

 Co., London and New York, 1891. Also "The Eise of the Theory of 

 Electrolytic Dissociation," etc., by H. C. Jones, Ph. D., Johns Hopkins 

 Hospital Bulletin, No. 87, June, 1898, p. 136. 

 6 



