Bkckke — Apparatus for Ohserving Reaction beMeen Gases, etc. 34 1 



The rate of stirring in these experiments varied from zero to about 1,000 

 revolutions per minute. The lower rates up to about 140 revolutions per 

 minute did not appreciably distort the surface of the water, but above this 

 speed the surface varied in shape and area with each variation in the speed 

 of the stirrer. The shapes assumed by the water surface are shown in fig. 6 ; 

 and it will be seen that they range from the nearly flat surface of still water 

 to the point at which the air is drawn down into the water in small bubbles. 

 At this point the surface area becomes uncertain, so that no conclusions can 

 be drawn from experiments at higher speeds. In the other cases the 

 surface area was taken to be approximately equal to that of a cone with the 

 vertical axis equal in depth to that attained by the lowest point of the water 

 surface. 



ExptS A.&B. 



Expr I 



Expt-2 



Exprs3.4&5 



Fig. 6. 



The progress of the absorption followed a linear law, as will be seen from 

 the graph, fig. 5, and this shows that the ferrous hydrate de-oxygenated the 

 water completely almost at once, so that the rate of solution of the oxygen 

 remained constant until all the hydrate was oxidized. 



The variation in the value of the rate of solution with stirring is shown 

 in the table and in fig. 7. On the graph the lower line shows the rate of 

 solution under the conditions of the experiment plotted against rate of 

 stirring, and the points lie approximately on a straight line. Hence under the 

 conditions of these experiments the rate of solution varies directly as the 

 rate of stirring. 



