22 BACTERIOLOGY. 



chemical The number of chemical agents having destruct- 



agents . . , 



ive action on bacteria is very large, and no attempt 

 will be made to speak of them all. It will suffice to 

 mention a few of the most common ones, and describe 

 the way they may be applied best. Chemical disin- 

 fectants may be used dry, in 1 solution, or in the form 

 pry dis- of gas. As examples of dry disinfectants, boric acid, 



infection . . 



bismuth, and lodoform may be mentioned. All are 

 used in concentrated form as they are obtained com- 

 mercially. Boric acid and bismuth are weakly bac- 

 tericidal, and have an antiseptic rather than a disin- 

 fectant action. lodoform when iodine is set free is 

 disinfectant. Their chief use is on infected wounds. 



Some of the most used disinfectant solutions are 

 as follows: 



Disin- Formalin (a 40% solution of 



fectant 



solutions formaldehyde gas in water) . 10 to 20 %. 



Bichloride of mercury i : 500 to i : 1000. 



Carbolic acid 5%. 



Chlorinated lime (chloride of 



lime) 5% (6 oz. to gal.). 



Hydrogen peroxide 20%. 



Alcohol 70%. 



Not all of these solutions are equally efficacious 

 for disinfecting, and each one has its advantages and 

 disadvantages. 



Formalin is an excellent disinfectant, and, in 

 addition, is also a good deodorant. It does not injure 

 fabrics, is not poisonous, and does not coagulate albu- 



