628 A MANUAL OF BACTERIOLOGY 



kill bacteria or germs ; antiseptics, by inhibiting bacterial 

 development, prevent sepsis or putrefaction ; and by 

 " disinfectant " is meant a substance which prevents the 

 action of, or destroys, infective matters, while deodorants 

 destroy or absorb foul-smelling gases the result of putre- 

 factive and similar processes. All germicides are disinfec- 

 tant and antiseptic, but many antiseptics, though pre- 

 venting or inhibiting the development of bacteria, are not 

 necessarily germicidal. 



Many deodorants act largely mechanically, and although 

 often not germicidal, and hence not ideal disinfectants, 

 are of some value in preventing the deleterious and depres- 

 sing effects of the emanations from decomposing organic 

 matter. Such are charcoal, ashes, dry mould, and peat 

 (peat has also a germicidal action). Other deodorants, 

 such as quicklime and chloride of lime, act chemically. 



The germicides and antiseptics may be considered together, 

 for although many antiseptics are not germicidal, all the 

 germicides in small amounts act as antiseptics. The prin- 

 cipal germicides and antiseptics are the halogen elements, 

 the mineral acids, a large number of metallic salts, phenol 

 and many coal-tar derivatives, and various organic bodies 

 and essential oils. 



Theory of chemical disinfection. The theory of chemical 

 disinfection is not yet fully understood. It is probable, 

 as suggested by Paul and Kronig, that the degree of ionisa- 

 tion of a solution may have an important bearing on its 

 disinfecting efficiency. 



Paul and Kronig l made a number of experiments on 

 the M. pyogenes, and spores of anthrax, with a view of 

 determining the effects of various acids, bases, oxidising 

 agents, and metallic salts on bacteria. The salts of 

 mercury, gold and silver exert a marked germicidal action, 

 strongest in the case of mercury, while the platinum salts 



1 Zeitschr.f. physikal. Chem. : 1896, xxi, p. 414. 



