CHEMICAL STERILIZATION, ETC. 65 



materials and objects i. e., to sterilize them; and it is 

 also possible by the same means to rob infected objects 

 of their dangerous infective properties without at the 

 same time sterilizing them i. e., to disinfect them. 

 This latter process depends upon the fact that the 

 vitality of many of the less resistant pathogenic organ- 

 isms is easily destroyed by an exposure to particular 

 chemical substances that may be without effect upon 

 the more resistant saprophytes and their spores that are 

 present. 



In general, the use of chemicals for sterilization is 

 not to be considered in connection with substances that 

 are to be employed as culture media, and their employ- 

 ment is restricted in the laboratory to materials that 

 are of no further value, and to infected articles that are 

 not injured by the action of the agents used, though for 

 particular purposes such volatile germicides as chloro- 

 form and ether may serve as exceptions to this. (See 

 Preservation of Blood-serum with Chloroform.) In 

 short, they are mainly of value in rendering infected 

 waste materials free from danger. For the successful 

 performance of this form of disinfection there is one 

 fundamental rule always to be borne in mind, viz., it 

 is absolutely essential to success that the disinfectant 

 used should come in direct contact with the bacteria to 

 be destroyed, otherwise there is no disinfection. 



For this reason, one should always remember, in 

 selecting the disinfecting agent, the nature of the mate- 

 rials containing the bacteria upon which it is to act, for 

 the majority of disinfectants, and particularly those of 

 an inorganic nature, vary in the degree of their potency 

 with the chemical nature of the mass to which they are 

 applied. Often the materials containing the bacteria 



