DESTRUCTION OF BACTERIA BY CHEMICALS. | 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), isa 
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 tu equal parts of feces or other filth and mixed 
with them will completely sterilize them within one hour. 
