46 ROYAL SOCIETY OF CANADA 
difficulty of obtaining water. .A pump like that used by Frankland 
was therefore employed. The apparatus, when set up with the pump 
included, is shown in Fig.3. The pump, which was made of brass, 
was provided with two taps, the entrance (A) and the exit (B). The 
former was attached to the experimental tube by means of the lead 
pipe, and a mercury manometer was fitted up in the position shown 
in the figure. The capacity of the pump was carefully measured in 
the laboratory; it was found that 55 strokes of the pump were neces- 
sary in order to draw 10 litres of air through the experimental tube. 
The air was drawn through the tube in the following manner. The 
entrance tap A was closed and the exit tap B was opened, where- 
upon the handle of the pump was pushed down as far as it would go. 
Next, the tap A was opened and the tap B closed; the handle of the 
pump was then pulled out to its extremity, and by this means a definite 
volume of air was drawn through the experimental tube. As the handle 
of the pump was drawn upwards, the mercury rose in the manometer. 
The fall of the mercury in the manometer arm to the level of the mer- 
cury in the glass beaker—a process which was watched by means of 
a mirror inclined at an angle of 45° to the ground—served to indicate 
that the air in the pump stood at atmospheric pressure. When this 
was observed, the tap A was closed, the tap B opened, and the 
handle of the pump was pushed downward in preparation for another 
stroke. The time required for 55 strokes, which were necessary in 
order to draw 10 litres of air through the experimental tube, was about 
25 minutes. With the aspirator, as we have seen, 10 litres could be 
drawn through in about 10 minutes, so that when the pump was used, 
the air passed through the experimental tube at somewhat less than 
one-half the speed it did when the aspirator was employed. The great 
advantage of the pump over the aspirator is its ready portability. 
The sterilization and transportation of the experimental and con- 
trol tubes were carried out as follows. The two tubes were each placed 
in a test tube closed with cotton wool stoppers. In order to prepare 
additional sterilised stoppers for the experimental and control tubes, 
for use after the aspiration of the air through the former, a short glass 
tube, similar to that used for the experimental and control tubes, was 
fitted up with cotton wool stoppers with small bits of a wooden or 
glass rod as cores. This tube was placed in a third stoppered test tube. 
The three tubes, with their contents, were sterilised by placing 
them in a dry steriliser at a temperature of 130°C. for three hours. 
The test tube contents enclosed by the test tubes could readily be 
transported to the place where the experiment was to be made without 
any fear of contamination. 
