90 



BACTERIOLOGY 



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 appara- 

 tus is useless. The older forms of hot-air sterilizers are so 

 constructed that their repair is a matter involving some time 

 and expense. To meet this objection I had constructed 



FIG. 12 



FIG. 13 



Laboratory hot-air sterilizer. 



Rose-burner. 



some years ago a sterilizer in all respects similar to the old 

 form except in the arrangement of the copper bottom. This 

 latter is made in such a way that it can easily be removed, 

 so that by keeping several sets of copper plates on hand 

 a new plate can readily be inserted when the old one is 

 burned out. 



In the employment of the hot-air sterilizer care should 



