GRY OUI BECO S Te eae See 
before and after recewing the Cambridge sewage effluent. 359 
the Royal Commission on Sewage Disposal, Vol. 1. Appendix, p. iv. 
From this reference it will be seen that the temperature exhibits 
a controlling influence on the amount of oxygen dissolved. For 
example, at 5°C., 89 cc. of oxygen are held by 1 litre of water, 
_ ote 
ae, 
ae 
Hours of sunshine for the two preceding days. 
—--- dissolved oxygen in c.c. per litre at 0° C. and 760 mm. 
=== hours of sunshine for the two days preceding that on which the sample 
was taken. 
Fig, 3. Curves showing the relationship between the diminution in the pollution 
and the gradual increase in the amount of oxygen in the river between 
Nov. 12th to Dec. 8th, and the gradual decrease in the temperature of the © 
water whereby more oxygen was dissolved from the atmosphere than in the 
warmer months. The fall of the oxygen figure on Oct. 29th was caused by an 
increased pollution of the river after rain. 
and 6°4.¢.c. at 20°C. The Commissioners consider that at about 
16°C. a clean river water may be taken as containing 7 cc. of 
oxygen per litre; but the authors found, at 16° C. (60° F.) and 
