GERMICIDES, ANTISEPTICS, AND ANTISEPSIS 263 



Superheated steam, or steam under pressure, is now in 

 general use in sterilizing surgical dressings and instruments, 

 and requires less time than ordinary steam. 



The salts of metals of high atomic weights come next in order. 

 Bichlorid of mercury and cyanid of mercury are the most 

 powerful of chemical germicides, but in the human body they 

 can be used in dilute solutions only, and in contact with 

 highly albuminous solutions, insoluble and inert albuminates 

 are liable to form, lessening the germicidal value. A i : 200 

 solution combined with an acid like citric will destroy the 

 spores of anthrax in one hour, but much weaker solutions will 

 destroy the anthrax bacilli in the blood, and for all practical 

 purposes a i : 2000 solution is sufficient, destroying bacterial 

 life in a few minutes. 



One per cent, solution soda lye, NaOH, kills most bacteria 

 in a few minutes, and, therefore, hot soapsuds is quite effec- 

 tive as a germicide. 



Phenol in 5 per cent, solution will destroy most of the bac- 

 teria in less than five minutes. Tricresol, a combination of 

 cresols, has three times the disinfecting power of phenol. 



Formaldehyd y in gaseous -form or in a liquid spray, is a very 

 efficient germicide, and from the fact that it is not destruc- 

 tive to fabrics or paper has_come into general use as a dis- 

 infectant. In combination with potassium permanganate 

 or in suitable generators it is employed in houses after infec- 

 tious diseases. It has no effect on insects, and where it is 

 necessary to destroy these, other agents, known as insecti- 

 cides, must be used in connection with the gas. The gas 

 should be in a moist state from 6 to 16 ounces for an ordi- 

 nary room are needed; the room should be made as air-tight as 

 possible, and the gas evolved as speedily as possible. 



In the permanganate method 8 ounces (by weight) of 

 potassium permanganate crystals are placed in a large tin 

 vessel ten times the capacity of the disinfectant used. One 

 pint of formaldehyd solution is quickly poured over the 

 crystals. Formaldehyd gas is thereby generated at once. 



