CHAPTER XXII 



HEAT STEAM DISINFECTION CHEMICAL DISINFECT- 

 ANTS THEORY OF DISINFECTION METHODS OF 

 DETERMINING DISINFECTANT POWER 



Disinfection x 



NATURAL agencies restrain the multiplication of disease 

 organisms, but enough survive to determine the persistence 

 of infective diseases, and to call for measures by which 

 communities attempt to cope with them. These measures 

 are broadly isolation, prophylactic inoculation, general 

 improvement in sanitation and nutrition, and disinfection. 

 In the present chapter the methods by which the fourth 

 means of protection may be applied are considered. Dis- 

 infection implies the removal or the destruction of infective 

 properties, but, for practical purposes, should be understood 

 to mean the killing of the infective organisms to which 

 those properties are due. For this purpose, the two 

 agencies ordinarily used are heat and chemical action, 

 though, in addition, other methods can occasionally be 

 employed for destroying or excluding micro-organisms. 

 Such are light, desiccation, and filtration. 



HEAT. Fire is the simplest and most efficient agent 

 for destroying infective matter. Burning should always 

 be employed where possible, as for rags, old clothing or 

 bedding, native huts, etc. 



For surfaces which would not be unduly injured, such 

 as stables, pens, yards, etc., a torch-fire generated by means 



1 See Hewlett, " Milroy Lectures," Lancet, 1909, vol. i. 

 623 



