DESTR UCTION OF BA CTEEIA B Y CHEMICALS. 1 57 



ployed, solutions of 1 to 500 and 1 to 1000 will suffice, 

 when brought in contact with bacteria in that strength, 

 to kill the vegetative forms within fifteen minutes, 

 the stronger solution to be used when much organic 

 matter is present. 



Biniodide of Mercury. This salt is very similar in 

 its effects to the bichloride. It is even somewhat more 

 powerful. 



Nitrate of Silver. Nitrate of silver in solution has 

 about one-fourth the value of the bichloride of mer- 

 cury as a disinfectant, but nearly the same value in 

 inhibiting growth. 



Sulphate of Copper. This salt has about 5 per cent, 

 of the value of mercuric chloride. 



Sulphate of Iron. This is a very feeble disinfectant. 



Sodium Compounds. A 30 per cent, solution of NaOH 

 kills anthrax spores in about ten minutes, and in 4 per 

 cent, in about forty-five minutes. Sodium carbonate 

 kills spores with difficulty even in concentrated solution, 

 but at 85 C. it kills spores in from eight to ten min- 

 utes. A 5 per cent, solution kills in a short time the 

 vegetative forms of bacteria. Even ordinary soapsuds 

 have a slight bactericidal as well as a marked cleansing 

 effect. The bicarbonate has almost no destructive effect 

 on bacteria. 



Calcium Compounds. Calcium hydroxide Ca(OH) 2 is a 

 powerful disinfectant; the carbonate, on the other hand, 

 is almost of no effect. A 1 per cent, watery solution of 

 the hydroxide kills bacteria which are not in the spore 

 form within a few hours. A 3 per cent, solution kills 

 typhoid bacilli in one hour. A 20 per cent, solution 

 added to equal parts of feces or other filth and mixed 

 with them will completely sterilize them within one hour. 



