123 STERILIZATION AND DISINFECTION 
the Arnold steam sterilizer too should be used on such substances as 
igars to prevent hydrolysis. 
Boiling. Practically no special apparatus is required by this 
method and any that is demanded may be quickly secured. Probably 
fifteen minutes is sufficient, for vegetative cells by spores are too resistant 
to be quickly killed. Surgical instruments may be sterilized by boiling. 
The water should be boiled for ten minutes before they are put in in 
order to prevent the possibility of rusting. : 
Streaming Steam. ‘The apparatus which is used in this method is 
much like the ordinary steamer which is available in the kitchen. 
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Fic. 39.—Arnold Steam Sterilizer. (Boston Board of Health Pattern.) 
In bacteriology the apparatus is known as the Arnold steam sterilizer. 
It was devised by Tyndall, and improved by Koch and Arnold. It 
consists of essentially a copper box with a false bottom through which 
the steam rises to escape at the top. ' There is no superheating in the 
Arnold as with the autoclave and it requires less attention. It may be 
used in two ways—continuous or intermittently: 
With the continuous method the material to be sterilized is heated 
for from thirty minutes to a hour and a half. This method has the 
disadvantage that such prolonged heating may cause changes in the 
materials. Di-, tri-, and poly-saccharides may be hydrolyzed proteins 
