ANTISEPTICS AND DISINFECTANTS. 159 



observations may be relied upon for practical 

 application. 



Hot Air and Steam. Koch, in conjunction with 

 Wolfhugel, also tested the value of hot air. A 

 similar plan was adopted as in disinfection with 

 chemicals. Bacteria and spores were subjected for 

 a certain time to a known temperature in a hot- 

 air chamber, and then were transferred to a 

 nourishing soil, or animals were inoculated. 



Paper parcels, blankets, bags, and pillows, con- 

 taining samples of micro-organisms wrapped up 

 inside, were also placed in the hot-air chamber, to 

 test the power of penetration of heat. 



The conclusions from such experiments were 

 as follows : 



Sporeless micro-organisms at a little over 100 C. 

 are destroyed in one hour and a half. 



Spores of bacilli require three hours at 140 C. 



If enclosed in pillows and blankets, exposure 

 from three to four hours to 140 C. is necessary. 



Spores of fungi require one and a half hours at 

 no 115 C. 



Further experiments showed that at the tempera- 

 ture 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 



