168 ApENrY—Unrecognised Factors in the Transmission of Gases through Water. 
first water-column, as was the case with sea-water, but that, on the contrary, it 
affected nearly equally the three water-columns. It may be inferred from this 
last observation that the streaming being less in distilled water than in sea- 
water, is due to the something causing it to be more slowly taken out of the 
air-current by the former than by the latter. 
The following experiment was also made with distilled water, wide bore, 
3mm., inlet and exit tubes being employed. The inlet tube dipped 25 mm. 
below the surface of the water :—— 
No. 12.—A tube 1980 mm. long and 24 mm. bore was filled with nitrogen-free 
distiiled water, and the air-current continued for twelve hours. 
Temperature of room,  . 5, NGC, 
Temperature of jacket, . > UNBOPO. 
Depth of Layer. 
0to 200 mm., : : : : . 10°56 
650 to 800 mm.,_ . : : : 5 SY 
1500t01600mm, . . . .  . 2°68 
Before aération, : : : : 5 ‘ogi 
The question arises, What is the active cause of the streaming ? The author 
does not desire at this stage of his investigation to advance definitely any explana- 
tion of the facts observed. One, however, which is suggested by the experiments 
that have been described, may be pointed out. It is that the streaming is possibly 
caused by minute dust-particles, or by other centres of condensation possibly of 
an electrical nature, carried by the air-current and taken up by the water, together 
with the gaseous constituents of the air; and that these bring about in some way 
a sufficient density of the dissolved or liquefied gases to render it possible for 
them to be drawn gravitationally downwards through the water. 
The fact that the streaming is more marked in sea- than in distilled water may 
be explained by assuming that the sea-water, from the salts which it holds in 
solution, is able to make more use of the centres of condensation introduced by 
the air which is bubbled through it. When sea-water and distilled water are 
separately shaken up with the air, the difference of behaviour of the two waters 
is, as is well known, very marked, it being easy to obtain a formation of small 
bubbles of air in sea-water to an extent quite impossible in distilled water. 
There can be no question from the experiments recorded that, if the air be 
completely washed, the surface of sea-water exposed to it will become saturated 
with nitrogen, but no streaming effects will take place. 
It is equally evident from these experiments that, whatever may subsequently 
be discovered to be the true cause of the streaming, its effect in large volumes of 
sea- or river-water under natural conditions must be of great importance, and of 
such dimensions that the effect of ordinary diffusion may, in comparison, be 
entirely neglected. 
