EFFECT OF ANTISEPTICS AND. DISINFECTANTS ON BACTERIA. 37 



Spores of bacilli require three hours at 140° 0. 



If enclosed in pillows and blankets, exposure from three to four 

 hours to 140° 0. is necessary. 



Spores of fungi require one and a half hours at 110° 0. to 

 115° 0. 



Further experiments showed that at the temperature necessary 

 for the destruction of spores of bacilli almost all fabrics are more or 

 less injured. 



Koch, in conjunction with Gaffky and Loffler, also investigated 

 the effect of steam under pressure and at the atmospheric pressure. 



Rolls of flannel with anthrax spores or earth spores, and a 

 thermometer wrapped up Inside, were subjected to steam, and 

 the results compared with the effect obtained with hot air. 



Thus in hot air four hours' exposure to a temperature of 130° C. 

 to 140° C. brought the temperature inside the roll to 85° C, and the 

 spores were not injured ; on the other hand, exposure to steam. 

 under pressure at 120° 0. for one and a half hours, raised the 

 internal temperature to 117° C. and killed the spores. 



By such experiments the superior penetrative power of steam- 

 heat was established. 



To test steam-heat at the atmospheric pressure, water was boiled 

 in a glass flask with its neck prolonged by means of a glass tube, the 

 temperature in which was found to be uniform throughout. Anthrax 

 and earth spores placed in the tube were found to be unable to with- 

 stand steam at 100° C. even for a few minutes. It was, therefore, 

 concluded that disinfection by steam at atmospheric pressure was 

 superior to hot air from its greater efficiency, and to steam under 

 pressure from the simplicity of the necessary apparatus. 



Parsons and Klein made some experiments which were more 

 in favour of dry heat than the above. These observers state that 

 anthrax bacilli are destroyed by an exposure of five minutes at 

 from 100° C. to 103° 0. and that anthrax spores are destroyed 

 in four hours at 104° C, or in one hour at 118° C. Guinea-pigs 

 inoculated with tuberculous pus which had been exposed for five 

 'minvites to 104° C, remained unaffected. They concluded that as 

 none of the infectious diseases, for which disinfecting measures 

 are in practice commonly applied, are known to depend upon the 

 presence of bacilli in a spore-bsaring condition, their contagia 

 are not likely to retain their activity after being heated for an 

 hour to 105° C. (220° Fahr.) 



In experiments with steam the results were in accordance 

 with those already given, and complete penetration of an object 



