20 BACTERIOLOGY FOR NURSES 



and that it has a corrosive effect upon metals. Its use then as a 

 disinfectant for sputa, feces, etc., is not advisable and care should 

 be exercised in using it about household plumbing. 



Potassium Permanganate ranks high as a germicide for certain 

 purposes ; its greatest usefulness is probably in surgical practice. 

 A 1 to 800 solution will kill vegetative forms. Koch found that a 

 1 to 20 solution killed spores in one day. Its application is some- 

 what limited on account of the readiness with which it combines 

 with organic material and thus becomes inert. 



Sodium Hydroxide (Caustic Soda) . Vegetative forms of bac- 

 teria are killed in a few minutes by a 1 per cent solution. Spores 

 are killed in about three quarters of an hour in a 4 per cent solution. 



Sodium Carbonate (Washing Soda). A 5 per cent solution will 

 destroy vegetative forms in a few hours. It has no effect upon 

 spores at ordinary temperatures. 



Sodium Bicarbonate has practically no germicidal properties. 



CALCIUM COMPOUNDS 



Slaked Lime. Lime is one of the best and cheapest disin- 

 fectants known. Slaked lime or calcium hydroxide is prepared 

 by adding one pint of water to two pounds of lime. A 1 per cent 

 solution of this freshly slaked lime will kill all vegetative bacteria 

 within a few hours. A 3 per cent solution kills typhoid bacilli 

 in one hour. Feces or other infected material may be completely 

 disinfected if mixed with equal parts of a 20 per cent solution and 

 allowed to remain in contact for two hours. Freshly slaked lime 

 should always be used ; if left exposed to the atmosphere it absorbs 

 more water and carbon dioxide and is converted into calcium 

 carbonate (marble), which is quite inert. 



Milk of Lime is slaked lime diluted with four to eight times 

 its volume of water. It should not be used if more than a few 

 days old unless well protected from the air. 



Chlorinated Lime, popularly known as Chloride of Lime or 

 Bleaching Powder, may be used either as a dry powder or in 

 solution. In the dry state it is frequently used in privy vaults 



