REVIEW. 
What per cent, solutions of the balsam of Peru 
are used? Mention a common base. 
X. —Describe the method of sterilizing water. 
Is it safe to sterilize water without filtering? And 
is distilled water safe to use in aseptic surgery 
without sterilizing? 
XI. —Describe the process of sulphur fumiga¬ 
tion. What are its disadvantages? 
XII. —What is formaldehyde? State why it 
is a more reliable substance to use for fumiga¬ 
tion than sulphur. Has its use any disadvan¬ 
tages ? 
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