DISINFECTION 401 



corrosive nature of these acids renders them unsuitable for 

 disinfecting purposes, and they are also very expensive. 



Chlorine, iodine, and bromine, are well-known disinfec- 

 tants, of which chlorine is the only one in general use, 

 the others being far too expensive. The free gas may be 

 employed or the gas held in lime ; this brings us to a con- 

 sideration of the question of fumigation, which may here be 

 conveniently dealt with. 



Fumigation. — In days gone by when diseases were 

 believed to be due to something in the air, and the sick 

 were supposed to give off emanations from the body which 

 poisoned the surrounding atmosphere and the contents of 

 the stable or room, it was a very rational method to meet 

 this state of affairs by generating a gaseous disinfectant. 

 But fumigation, though still practised, now holds a very 

 subordinate position, for the reason that pathogenic 

 organisms do not float in the air unless in a dry condition, 

 but prefer to adhere to substances such as walls, woodwork, 

 stable fittings, flooring, etc. Therefore, instead of trusting 

 to the action of a gaseous disinfectant, we prefer to at once 

 deal with the infected surface by applying the disinfectant 

 directly to it. 



Experimental enquiry shows how extremely difficult it is 

 to kill pathogenic organisms in buildings by aerial disinfec- 

 tion only. The gas to be of any use as a destroyer must 

 exist in a certain percentage for a definite period, and this 

 is most difficult to maintain. Even with every care in 

 papering up and closing all openings, cracks, windows, 

 ventilators, air bricks, etc., there are still sure to be 

 unobserved sources of leakage, which prevent the gas being 

 kept at the percentage amount requisite for disinfection. 

 It is impossible to hermetically seal the building, and 

 without this fumigation is of little use. 



There is no objection to fumigating a building as part of 

 the disinfecting programme, but by itself it must not be 

 trusted to or it will certainly fail. 



Chlorine gas is heavy and diffuses badly, if employed as 



a fumigant it should be generated in several parts of the 



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