Apvrenty—On Absorption of Oxygen by Polluted Waters, §c. 281 
volumes of the same polluted water, and that this law is 
applicable to all polluted waters undergoing purification by 
bacterial fermentation, provided that the dissolved oxygen is in 
excess of the fermenting matters. 
These results have been confirmed by other observers; and it 
is now agreed that the determination of the extent and rate of 
absorption of oxygen by polluted waters with reference to the 
question of the protection of waterways from over-pollution is of 
fundamental importance. Unfortunately up to the present time 
the method employed for the purpose has been too elaborate and 
too slow for practical purposes; and the result has been that these 
important determinations are even now seldom made. 
The apparatus which is the subject of this communication 
has been devised to meet this want. Its form is shown by the 
above diagram. 
