Apvrnry— Unrecognised Factors in the Transmission of Gases through Water. 165 
observed to rise above the immediate neighbourhood of the crystal, and become 
mixed with the water above it. 
The results of the last two experiments proved, as was anticipated, that the 
downward streaming takes place so rapidly, when the surface of the water exposed 
to the air is continuously agitated, that long columns of water are completely 
saturated with atmospheric gases with comparative rapidity. 
Experiments were next made in which the surfaces of the water-column were 
kept broken by means of slow currents of air. It was thought that by their 
means it would be easy to make comparative observations on the effect of agitating 
different thicknesses of the surface-layers of two or more columns of water by the 
same disturbing cause. 
No. 6.—Two tubes, each 1980 mm. long and 24 mm. bore, were filled with nitrogen- 
free sea-water. Each tube was fitted with an indiarubber cork, and fine glass inlet and 
extt tubes of 3 mm. bore, and was connected in series, so that the same current of ar could 
be drawn through the surface-layers of each column of water. The wmlet tube, through 
which the current of air was first drawn, dipped 100 mm. below the surface, and the second 
inlet tube dipped 10 mm. below the surface of the second column of water. The current of 
air was not previously filtered. It was continued for twenty-five hours. At conclusion, 
temperature of room was 19°5°, and of the jacket 15°7° C. 
Sea-water saturated at 19°50° C contains 10°50 cc. N, per litre. 
Depth of layer below surface. 1 2 
1to 100mm., OC o¢ 10°57 ae °° 8-01 
1500 to 1600 mm., ore 2% 8°91 O00 5 0 4:08 
Before aération, “6 as 1:58 ae 50 1°56 
No. 7.—Similar to the experiment No. 6, with the exception that the inlet tube dipped 
10 mm. below the surface in the first column of water, and 100mm. im the second column. 
The current of air was continued for twenty hours. Temperature of room at conclusion 
was 18°2°, and of the jacket 14:‘9° C. 
Sea-water at 18:2° C. contains 10°68 cc. N, per litre. 
Depth of layer below surface. 1 2 
1 to 100mm., a oe 10:07 50 50 9:95 
1000 to 1100 mm., we es 6°05 
1200 to 13800 mm., 00 00 9°61 
1700 to 1800 mm., a a 6°26 a Sc 2:15 
Before aération, a is 1°61 a an 1°56 
The sea-water employed for the experiments thus far recorded was collected 
in Dublin Bay. It had been stored in partially full bottles for some weeks previous 
to use. It contained 19°57 grams chlorine per litre. 
From the foregoing results it appears that the rate of aération, as a consequence 
of the streaming, was not materially affected by difference of depth of the air 
