54 DESTRUCTION OF BACTERIA BY CHEMICALS 



500 for one-half hour when any such organic material 

 is present. The disadvantages of bichloride are, beside 

 that mentioned above, that it corrodes metals and is 

 rather hard on the skin. It is well to add some coloring 

 matter to the solution for the purpose of identification, 

 since this is a rapidly acting, corrosive, deadly poison. 

 Great care should be used in keeping the tablets and 

 solutions, as many accidents have occurred. Being 

 odorless it attracts no attention. 



Silver Nitrate. Park says that this salt has one- 

 fourth the value of the preceding as a disinfectant, 

 but nearly the same value in restraining bacterial 

 growth. It is not a very practical disinfectant, because 

 of its destructive action on the skin and fabrics, but 

 it can be used with value in diphtheria. Solutions 

 should be freshly prepared in 1-2 per cent, strength. 



Copper Sulphate. This chemical is potent against 

 typhoid in water in the presence of little organic 

 material in the strength of 1 to 400,000 in twenty-four 

 hours. 



Sodium Hydroxide (caustic soda). This substance is 

 very destructive to fabric and to the skin, but kills, 

 in the strength of 1 to 100, vegetative bacteria in a 

 few minutes, or spores are destroyed by 4 per cent, 

 solution in forty-five minutes. 



Sodium Carbonate.- This chemical, advantageous for 

 boiling instruments, kills vegetative forms in 5 per 

 cent, solution very quickly, or spores in boiling water 

 in about five minutes. 



"Chloride of Lime" (chlorinated lime). This chemical 

 is also known as bleaching powder. There is a differ- 

 ence of opinion as to its composition. Its power de- 



