THE ACTIONS OF CERTAIN ANTISEPTICS. 143 



shown that the greater amount of the oxidation which takes 

 place when this agent is brought into contact with bacteria 

 occurs after the organisms are killed. Such an observation is, 

 however, not conclusive as to the non-efificiency of the oxidation 

 process, for the death of the bacteria might be due to the oxida- 

 tion of a very small part of the bacterial protoplasm. Apart 

 from the chemical nature of antiseptic agents, the physical fac- 

 tors concerned in their solution, especially when they are elec- 

 trolytes, probably play a part in their action. The part played 

 by such factors is exemplified in the important fact that a strong 

 solution acting for a short time will have the same effect as a 

 weaker solution acting for a longer time. From what has been 

 said it will be realised that the real causes of a material being 

 an antiseptic are very obscure, and at present we can only have 

 a remote idea of the factors at work. 



The Actions of Certain Antiseptics. — Here we can only briefly 

 indicate certain results obtained with the more common members 

 of the group. 



Chlorine. — All the halogens have been found to be power- 

 ful antiseptics, but from the cheapness with which it can be pro- 

 duced chlorine has been most used ; not only is it the chief 

 active agent in the somewhat complex action of bleaching pow- 

 der, but it is also the chief constituent of several proprietary 

 substances, of which " Electrozone " is a good example. This 

 last substance is made from electrolysing sea water, when mag- 

 nesia and chlorine being liberated, magnesium hypochlorite and 

 magnesium chloride are formed. In the action of this substance 

 free hypochlorous acid is formed, and the effect produced is 

 thus similar to that of bleaching powder. Nissen, investigating 

 the action of the latter, found that \\ per cent killed typhoid 

 bacilli in faeces ; and Rideal found that i part to 400-500 disin- 

 fected sewage in fourteen minutes, and Del6pine's results show 

 that I part to 50 (equal to .66 per cent of chlorine) rapidly kills 

 the tubercle bacillus, and i part to 10 (equal to 3.3 per cent) 

 killed anthrax spores. Klein found that .05 per cent of chlorine 

 killed most bacterial spores in five minutes. 



Iodine Terchloride. — This is a very unstable compound of 

 iodine and chlorine, and though it has been much used as an 

 antiseptic, seeing that the substance only remains as IClg in an 

 atmosphere of chlorine gas, it is open to doubt whether the 



