CHAPTEE XII 



DISINFECTANTS 



A LEAKING drain, an open cesspool, heaps carelessly 

 thrown together of offensive animal or vegetable 

 matter, are likely to contaminate food or water, while milk 

 absorbs obnoxious gases and germs even more readily. 

 Poisons which destroy such harmful pests are usually 

 termed disinfectants, and under this heading are grouped 

 also antiseptics and deodorants. 



Disinfectants proper are directed against the germs of 

 infectious diseases contained in excreta or in foul drains, 

 and also against unpleasant and sometimes dangerous 

 odours and exhalations given off by decaying organic 

 matter. These dread enemies may be successfully combated 

 by Sunlight and Heat, solutions in water of Carbolic Acid, 

 preparations such as Izal or Jeyes' Fluid, Permanganate of 

 Potassium, Formalin, or Sulphur Dioxide — the gas which is 

 produced by burning sulphur in the open air. 



Mercuric Chloride is another most powerful agent, but is so 

 virulent a poison that it should be used with the greatest 

 caution; a solution of one part in one thousand parts (ro^oo) 

 of water will disinfect and destroy all forms of life. 



Important considerations in selecting a disinfectant are 

 cheapness and accessibility, for there is often little to choose 

 between their respective results. 



Sunlight is not so important an auxiliary in England as 

 in many foreign countries, for its continuance and clearness 

 often cannot be depended upon, though it is a powerful 

 germicide. The spectroscope has disclosed that it is the blue, 

 violet, and ultra-violet rays which alone have the power of 

 destroying germs. 



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