1901-2.] Dr Noel Paton on Dissolved Oxygen in Water . 147 
into the large Wolff’s bottle filled with nitrogen, which contained 
only small traces of oxygen, and kept for two days, when the 
water contained 2 cc. oxygen per litre. 
On the second day a young rainbow trout was placed in each 
of these vessels. 
A. placed in Tyne water (400 cc.) oxygenated at 4.56 p.m. 
B. ,, ,, (550 cc.) not ,, at 4.59 ,, 
C. ,, water (2000 cc.) under nitrogen at 5.3 ,, 
The fish in B. died at 8.45 (in 4 hours), that in C. died during 
the night, while that in A. was alive and well next morning. The 
water then contained 2 cc. oxygen per litre. 
This observation seems to show that there was not any chemi- 
cal substance prejudicial to fish life in the water of the Tyne 
Estuary at a time when many salmon were being found dead in it. 
Experiment II. — 1200 cc. water were put in the Wolff’s bottle 
as already described. At 10 a.m. next day the water contained 
3 cc. oxygen per litre. At 10.30 a trout of 4 ‘5 grm. was in- 
troduced. It died at 6.30 p.m. — after eight hours. 
At 10 a.m. next day the oxygen was 0 cc. per litre. 
At 10.40 another fish of 4 ‘5 grm. was put into the bottle, and at 
1.25 it was lying on its side gasping. It was taken out and 
placed in tap water, where it recovered. 
Experiment III. — A. 2000 cc. of water were placed in the 
Wolff’s bottle, and B. 1600 cc. in a large flask. At 10.30 a.m. 
next day the water in — 
A. contained 3 cc. oxygen per litre. T. 14° C. 
B. ,, 6 cc. ,, ,, ,, 
Three small trout, weighing 2 grm., 3*7 grm., and 1*5 grm., 
were placed in the bottle, and three, weighing 3 grm., P5 grm., 
and about 3*5 grm., were put in the flask, at 10.30 a.m. 
At 2.45 the small trout in A. was dead. (4 hours.) 
At 5.10 both remaining fish were sluggish. 
Oxygen = 2 cc. T. 14° C. 
At 6.10 the second small fish died. (7 hours.) 
