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13 
last gas was extraordinary, the highest percentage found being 48*3, and 
the proportion to 100 oxygen being 281 ! It was frequently noticed, that 
the proportion of carbonic acid to oxygen in bottom water bore a much 
closer relation to the abundance of animal life than to its depth, and in 
several instances, where the depths were nearly the same, the speaker had 
ventured a prediction as to the abundance, or otherwise, of animal life 
of high types, as shown by the dredge, from the proportion of carbonic 
acid in the bottom- water previously obtained and analysed. In every 
instance, the prediction so made was correct. This excess of carbonic 
acid, however, does not extend upwards very far from the bottom, as the 
following series, where the samples of water were collected at various 
vertical depths over the same spot, will show. 
750 Fathoms. 800 Fathoms. 862 Fathoms— bottom. 
Oxygen - - - - 188 - 17"8 - 17 2 
Nitrogen - - - - 49 3 - 48 '5 - 34 -5 
Carbonic Acid - - 319 - 337 - 48 '3 
100-0 100-0 100-0 
The speaker had observed that even when animal life was very abundant 
on bottoms less than 200 fathoms from the surface, this excess of carbonic 
acid did not exist, and ho was inclined to believe that up to this depth 
there was so constant an aeration of the water at the bottom, by diffusion 
from, the surface, (whether of the water itself, or of the gases dissolved in 
it) that the excess could not accumulate. He pointed out that the coinci- 
dence between this depth and the greatest depth at which vertebrate 
animals (fish, &c.) were found, was suggestive. 
The examination of the specific gravity of sea-water at various depths 
had been made, but the results were void of much interest. In the open 
sea, away from the mouths of rivers, the specific gravity, whether of sur- 
face, intermediate, or bottom water, varied little from 1027*8, that of fresh 
water being lOOO'O. In some cases the water from great depths, when 
brought to the same temperature as that at the surface, was slightly lower 
in specific gravity, and occasionally during wind the specific gravity of 
surface-water slightly increased. 
The test applied to the sea- water for the presence of organic matter was 
that known as the Permanganate, or Chameleon test. The mode adopted 
by Dr. W. A. Miller was employed, with an addition suggested by Dr. 
Angus Smith, which enabled the operator to distinguish between the 
organic matter in a state of decomposition from that which i3 only 
decomposable. 
