STERILISATION 95 



walls has been determined. Silk threads, soaked in cultures containing 

 various pathogenic organisms, were attached to boards, and lime-water 

 applied with a camel's-hair brush ; anthrax bacillus (without spores) 

 and some others were killed, after a single application, in twenty-four 

 hours, but three applications were not sufficient to kill the tubercle 

 bacillus. The spores of anthrax were not killed by two hours' exposure 

 to milk of lime containing twenty per cent, of calcium oxide. We 

 may regard this disinfectant as being very useful, except in cases 

 where it is suspected that very resistant organisms are present. It 

 has the further advantage of being harmless to the human system, and 

 can therefore be freely used in breweries, malt-houses, etc. 



Boracic Acid. Bandages for wounds are usually sterilised by soaking 

 them in boracic acid. It has also been employed for preserving tinned 

 meats, milk, etc. ; but as cases of cumulative poisoning have been 

 traced to this substance, its use as a food-preservative is now forbidden 

 by law. 



With regard to exact determinations of its value, it has been found 

 that a 2 *7 per cent, solution can destroy the bacillus of typhoid in 5 

 hours, and a T5 per cent, solution can do the same to the cholera 

 bacillus in the same time. Anthrax spores cannot be killed by boracic 

 acid ; in fact, it has been found that a 5 per cent, solution was unable 

 to destroy them, even after 5 days' immersion. Its use, in the form 

 of borax, is recommended in the preparation of starch paste, because 

 it prevents the paste from being attacked by moulds. 



Hydrogen Peroxide. The destructive effect of this substance is 

 not in virtue of its own poisonous effect on the living matter of 

 bacteria and allied organisms, but rather owing to the fact that it 

 liberates oxygen easily, and it is the oxygen which destroys. The 

 price of this article is too prohibitive to enable its use to become 

 general, otherwise, in the fermentation industries, there would 

 probably be a great demand for it, inasmuch as it can easily be made 

 to split up into water and oxygen, both substances harmless to the 

 human system. The equation is expressed thus : 



H 2 2 = H 2 + 0. 



hydrogen water oxygen 

 peroxide 



In the manufacture of jams, pickles, etc., its use is strongly recom- 

 mended. Its value to the medical profession is still a debated point. 

 Miquel, in his list, dubs it a substance eminently antiseptic, and states 

 that, even in the proportion of 1 : 20,000, the development of germs is 

 considerably hindered. Sternberg's conclusion is that, unless some 



