CHAPTER VIII 



SUNLIGHT AS A DISINFECTANT 



\ A 7 HAT has been said in the preceding chapter 

 with reference to the germicidal value of heat 

 and desiccation would indicate the utility of exposing 

 infected articles to sunshine in the open air, as has 

 long been the custom in domestic sanitary practice. 

 But it has been ascertained by carefully conducted 

 experiments that such exposure has an additional 

 value on account of the disinfecting action of the 

 sunlight per se. As long ago as 1877 two English 

 experimenters (Downes and Blunt) in a communica- 

 tion made to the Royal Society of London presented 

 evidence showing that sunlight has an injurious effect 

 upon bacteria, and that sterilisation of cultures in 

 liquid media could be effected by prolonged exposure 

 to direct sunlight. Since then many experiments 

 have been made by different observers and the fact 

 has been fully confirmed. Even the spores of cer- 

 tain bacilli are destroyed by long exposure to sun- 



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