STERILIZATION — ANTISEPSIS — FOOD PRESERVATION 



67 



above the surface of the water is for the reception of the tubes 

 and flasks that are to be steriUzed. The Arnold steam steril- 

 izer is somewhat more complicated but is very convenient and 

 efficient. It consists of a cylinder of tin or copper with a cover, 

 which is enclosed in a movable cylindrical outer cover or hood. 

 The inner cylinder has an opening in the bottom through which 

 steam may enter, the steam coming from a small chamber under- 

 neath with a copper bottom to 

 which the flame is applied. The 

 peculiarity of this form of steril- 

 izer consists in the fact that the 

 steam which escapes from the 

 sterilizing chamber condenses be- 

 neath the outer cover or hood 

 and falls back upon the pan over 

 the chamber in which the steam is 

 generated. The bottom of this 

 pan is perforated with three small 

 holes, which allow the water of con- 

 densation to return into the cham- 

 ber where the steam is generated. 

 The sterilizer, therefore, to a cer- 

 tain extent, supplies itself with 

 water, although not by any means 

 perfectly. It is, however, less 

 likely to boil dry than other forms 

 of sterilizers, and it has the ad- 

 vantage of being reasonably cheap and quite effective. The 

 space inclosed by the hood also serves as a steam-jacket and 

 helps to prevent fluctuations in temperature. A great im- 

 provement upon the ordinary Arnold sterilizer is the modifica- 

 tion of it devised by the Massachusetts Board of Health. 



In the use of this, or any form of steam sterilizer, the time is 

 noted from the period when boiling is brisk and it is evident that 

 the sterilizing chamber is filled with hot steam; or, what is better. 



Pig. 30.- 



-Diagram of the Arnold 

 steam sterilizer. 



