412 CLINICAL BACTERIOLOGY. 



at a temperature of 80 C. (176 F.), and spores only after 

 exposure for three hours at a temperature of from 140 C. 

 (284 F. ) to 160 C. (320 F.). Steam may be employed 

 still or streaming, and further under tension and super- 

 heated. Live steam is most available for large disinfecting 

 apparatus. These represent in principle nothing more 

 than the Koch steam-chest Into a large vessel or an air- 

 tight chamber, steam -vapor at a temperature of 100 C. 

 (212 F.) is so introduced that it displaces all of the air 

 and comes in contact with every portion of the articles to 

 be disinfected. As in the steam-chest, in these larger 

 apparatus also complete sterilization is effected in from 

 fifteen to thirty or sixty minutes, in accordance with the 

 size of the articles. Steam under pressure (120 C. 248 

 F.) is employed for purposes of disinfection, especially 

 in France. With its aid sterilization is effected quickly 

 and with absolute certainty when provision is made for the 

 escape through a valve of all the air contained in the appa- 

 ratus. 



Cold inhibits the development of, but scarcely destroys, 

 resistant microorganisms. Anthrax -spores retain their 

 vitality and virulence for more than twenty-four hours at a 

 temperature of 130 C. (266 F.). 



Of greater importance are chemic disinfectants. These 

 consist of all sorts of chemic agents (acids, alkalies, salts, 

 aromatic substances, etc.), and the large majority cause 

 enfeeblement and inhibit the development of the bacteria, 

 and in sufficient concentration effect their destruction. 



As the chemic disinfectants are, in the nature of things, 

 almost invariably employed in aqueous solution, recent in- 

 vestigations in the domain of physical chemistry with regard 

 to the nature of the solutions have not only acquired sig- 

 nificance for the comprehension of observed phenomena, 

 but they have also yielded valuable aid in the selection 

 and application of disinfectants. In the course of these 

 observations, which were begun by Dreser, then continued 

 especially by Paul and Kronig, and at the same time also 

 by Scheurlen and Spiro, it has developed that the changes 

 which the dissolved substances undergo in the solution 

 through the action of the solvent are of decisive import- 

 ance with regard to the mode of action. According to the 

 views of Arrhenius, now almost generally accepted as cor- 

 rect, a dissociation (division) of the dissolved salts, acids, 



