12 
winds, the surface-water was more highly aerated, containing less carbonic 
acid, and more oxygen. 
Average of 5 analyses of surface-water during windy weather : — 
Per Cent. Proportion. 
Oxygen- - - - 2910 - 100 
Nitrogen - - - 52-87 - 182 
Carbonic Acid - 18*03 - -62 
100-00 
That this change is really due to the agitation of the water in contact 
with air is shown by the following analyses of water taken from abaft the 
paddles, at full speed. 
I. Proportion. II. Proportion. 
Oxygen - - 37 1 - 100 . 45 '3 - 100 
Nitrogen - - 59 '6 - 161 - 49 -1 - 108 
Carbonic Acid 3 3 - 9 - 5-6-12 
100-0 100-0 
It appears, therefore, that the superficial disturbance of the sea by 
atmospheric movement is absolutely necessary for its purification from 
the noxious effects of animal life and decomposition. 
As a general rule, the examination of water below the surface showed 
that the oxygen diminished and carbonic acid increased with the depth, 
(the nitrogen remaining nearly constant), though not in proportion to it. 
Average of 24 analyses of intermediate water : — 
Per Cent. Proportion. 
Oxygen- - - - 22 03 - 100 
Nitrogen - - - 51-82 - 235 
Carbonic Acid - 26*15 - 119 
100 00 
Average of 35 analyses of bottom water :- 
Per Cent 
Oxygen - - - 19 53 
Nitrogen - - - 52-60 
Carbonic Acid - 27*87 
100-00 
Hence it appears that there is only about four-fifths as much oxygen at 
the bottom as at the surface, and in proportion to the oxygen, nearly twice 
as much carbonic acid, (83 to 143.) In some cases the amount of this 
Proportion 
100 
261 
143 
