6 APPARATUS 



effected by streaming steam at 100 C. It is usual to maintain this 

 temperature for fifteen to twenty-five minutes each day for three suc- 

 cessive days. The success of this procedure fractional sterilization 

 is due to the fact that many spores which were not killed at the first 

 steaming have developed into vegetative forms within twenty-four 



FIG. i. Dressing sterilizer showing cylinder containing water (K) heated either 

 by gas or Primus kerosene lamps. 



hours, and when the steam is then applied such forms are destroyed. 

 Experience has shown that all the spores have developed by the time 

 of the third steaming, so that with this final application of heat we 

 secure perfect sterilization. 



It is customary to use the Arnold for sterilizing gelatin and milk 



