688 GENERAL THERAPEUTIC MEASURES 



sulphurous acid gases for this purpose, although recom- 

 mended in text books, is futile, and by irritating the respira- 

 tory mucous membrane, accomplishes moie harm than good, 

 since a congested surface offers a more suitable field for 

 bacterial growth. Air, on the other hand, may be a medium 

 of infection when contaminate^ with dust containing patho- 

 genic bacteria (B. tuberculosis). Sunlight is prejudicial 

 to the vitality of bacteria. Whereas, the bacilli of tubercu- 

 losis will live almost indefinitely in dark, damp places, they 

 quickly succumb to sunlight and dry air. Sunlight and pure 

 air are, then, imperative for both the immediate and pre- 

 ventive treatment of germ diseases. Heat is the most 

 powerful agency for disinfection at our command.* Dry 

 heat, to be efl&cacious, must be applied at a temperature of 

 140° C. (284° F.) for three hours to kill all bacteria and 

 spores ; but this degree of heat scorches most fabrics and 

 destroys many materials. Boiling water quickly kills all 

 non-spore-bearing pathogenic bacteria, and these include 

 most of the organisms causing the common contagious and 

 infectious diseases (tuberculosis and anthrax excepted). 

 Two hours of continuous boiling will not destroy the most 

 resistant of micro-organisms — the spores of the hay ba- 

 cillus — but moist or saturated steam, at 230° F., will infallibly 

 kill any spores whatsoever within a few minutes. Fire is 

 the most complete disinfectant, because it not only destroys 

 germs, but their food and products. Water, like air, dilutes 

 germs and aids oxidation and destruction of oiganic matter ; 

 but, again like air, drinking water may be the source of in- 

 fection when suflBcieutly contaminated. 



MECHANICAL MEANS OF PROCURING ASEPSIS. 



The placing of sole reliance upon chemical agents for 

 surgical antisepsis, in relation to the body, is a common 

 error. These agents may damage denuded tissue, and do 

 not reach the micro-organisms buried in the tissues. There- 

 fore, it is impossible to render living tissue absolutely 

 aseptic, or sterile, by merely bathing it with chemical solu- 



