CHEMICAL STERILIZA TION AND DISINFECTION. 63 



iron bottom of the chamber. It consists of several 

 copper plates placed one above the other, but with a 

 space of about 4 to 5 mm. between the plates. These 

 copper bottoms after a time become burned out, and 

 unless they are replaced the apparatus is useless. The 

 older forms of hot-air sterilizers are so constructed that 

 their repair is a matter involving some time and ex- 

 pense. To meet this objection I have had constructed a 

 sterilizer in all respects similar to the old form except in 

 the arrangement of this copper bottom. This is made 

 in such a way that it can be easily removed, so that by 

 keeping several sets of copper plates on hand a new one 

 can readily be inserted when the old one is burned out. 



In the employment of the hot-air sterilizer care should 

 always be given to the condition of the copper bottom ; 

 for the direct application of the heat to the sheet-iron 

 plate upon which the substances to be sterilized stand, 

 results not only in destruction of the apparatus, but fre- 

 quently in destruction of the substances undergoing ster- 

 ilization. 



Since the temperature at which this form of steriliza- 

 tion is usually accomplished is high, from 150 to 180 

 C., it is well to have the apparatus encased in asbestos 

 boards, to diminish the radiation of heat from its sur- 

 faces. This not only confines the heat to the apparatus, 

 but guards against the destructive action of the radiated 

 heat on woodwork, furniture, etc., that may be in the 

 neighborhood. 



CHEMFCAL STERILIZATION AND DISINFECTION. 



As has already been stated, it is possible by means 

 of certain chemical substances to destroy all bacteria 



