1 6O BACTERIOLOGY. 



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. 140 C. brought the 

 temperature inside the roll to 85 C., and the 

 spores were not injured ; on the other hand, ex- 

 posure to steam under pressure at i2oC. 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 tempera- 

 ture in which was found to be uniform throughout. 

 Anthrax and earth spores placed in the tube were 

 found to be unable to withstand 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 to from 

 1 00 C. to 103 C., and that anthrax spores are de- 

 stroyed in four hours at 104 C., or in one hour at 

 1 1 8 C. Guinea-pigs inoculated with tuberculous pus 

 which had been exposed for five minutes to 104 C., 



