As is to be expected, the passage of so large a volume of air through
the sulphuric acid in such a relatively small space results in a slight
acid odor in the air-current leaving this absorber. The amount of
material thus leaving the absorber is not weighable, as has been shown
by repeated tests, but nevertheless there is a sufficiently irritating
acid odor to make the air very uncomfortable for subsequent respiration.
It has been found that this odor can be wholly eliminated by passing the
air through a can containing cotton wool and dry sodium bicarbonate.
This can is not weighed, and indeed, after days of use, there is no
appreciable change in its weight.