214 Sterilization and Disinfection 



prevention of albuminate of mercury formation. Liibbert and Schneider 

 and Behring have used sodium chlorid and ammonium chlorid. Both 

 of these salts diminish the germicidal action of the mercuric salt about 

 one-half. Notwithstanding this, however, the "antiseptic tablets" in 

 common use for surgical and household purposes contain one or both 

 of these salts, added for the purpose of preventing the precipitation of 

 the mercuric compounds formed in the presence of alkaline albuminous 

 materials, such as blood, pus, sputum, feces, etc. 



The addition of about 25 per cent, of alcohol to the solution of the 

 mercuric salt greatly enhances its value. Strong alcoholic solutions 

 are, however, less useful than aqueous solutions, for the 95 or 100 per 

 cent, alcohol dehydrates the micro-organisms and prevents the diffusion 

 currents by which the mercury is carried into their substance. 



For most purposes a i : 2000 solution of the mercuric chlorid is to be 

 recommended. 



Silver Nitrate (AgNO 3 ). The solutions of this salt are probably 

 more useful than the frequency of their employment might sug- 

 gest. They have, however, the disadvantages of decomposing 

 when kept in the light and of making black stains when applied 

 in concentrated form to the skin or dressings. 



The germicidal power of the salt in aqueous solution is less than 

 that of the mercuric chlorid, but the power in albuminous fluids 

 is greater. Anthrax spores in blood-serum are killed in seventy 

 hours in a i: 12,000 solution. The addition of other salts, as 

 ammonium salts, interferes with the germicidal activity by in- 

 hibiting ionization. 



Combinations of the silver nitrate with albuminous compounds, 

 and variously known as argonin, argentum casein, argyrol, pro- 

 targol, etc., have been used where the disinfecting power of the 

 silver is sought for with the least amount of irritation and the 

 deepest degree of penetration, as in the treatment of gonorrhea. 

 Potassium Permanganate (KMnOJ. Solutions of this salt seem to 

 act by virtue of a strong oxidizing power. In 2 per cent, solu- 

 tions anthrax spores are killed in forty minutes; in 4 per cent, 

 solutions, within fifteen minutes. Koch's experiments showed 

 less activity of the germicidal power against anthrax spores. 

 In his hands a 5 per cent, solution seemed to require about a day 

 to effect complete distraction. A i per cent, solution kills the 

 pus cocci in ten minutes; a i : 10,000 solution kills plague bacilli 

 in five minutes. 



The chief difficulty in the way of successfully employing this 

 salt is that it is quickly reduced and its strength destroyed by the 

 organic substrata in which the bacteria are contained. 

 HALOGENS AND COMPOUNDS. Those with the lowest atomic weight 



have the greatest disinfecting power. 



Chlorin. This is usually employed in the form of chlorinated 

 lime. It seems to be a mixture of calcium hypochlorite, Ca(ClO 2 ), 

 and calcium chlorid, CaOCl 2 . The addition of any acid, in- 

 cluding the atmospheric CO 2 , causes the evolution of Cl. The 

 powder is readily soluble and solutions of i : 500 kill vegetative 

 forms of most bacteria in a few minutes (not, however, resisting 

 spores). 



A proprietary compound known as "electrozone," made by 

 electrolyzing sea-water in such a manner that magnesia and 

 chlorin are liberated and magnesium hypochlorite and magne- 

 sium chlorid formed, is a cheap and useful chlorin disinfectant. 

 Nissen found that 1.5 per cent, of it killed typhoid bacilli in a 

 few minutes; Rideal, that i : 400 to 500 dilutions of it disinfected 

 sewage in fifteen minutes; and Delepine, that i : 50 (equal to 



