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XVII.—On the Composition of Oceanic and Littoral Manganese Nodules

Published online by Cambridge University Press:  17 January 2013

Extract

The following analyses were made some years ago, principally with the object of ascertaining the state of oxidation of the manganese in the nodules. The nodules examined came from three different localities, two of them oceanic and the third littoral. Samples marked I., II., and III. are from nodules brought up in the trawl on board the “Challenger,” on 13th March 1874, in lat. 42° 42′ S., long. 134° 10′ E. The depth of the water was 2600 fathoms, and the temperature of the bottom water 0·2° C. The density of the bottom water was 1·02570 at 15·56° C. Being from a high southern latitude, and therefore near the source of surface aeration, the water is highly charged with atmospheric gases, especially oxygen. It contained, per litre, 18·4 c.c. of mixed nitrogen and oxygen, of which 31·81 per cent, was oxygen, and 27·33 c.c, or 53·7 milligrammes, loosely-bound carbonic acid. The position of the station is about 400 miles south-west of the nearest part of the Australian coast, and about 500 miles west of Tasmania. It was the deepest water observed in the Antarctic voyage between the Cape of Good Hope and Melbourne. The haul was a very abundant one, and a few notes which I made at the time may be interesting:—“The water was found unexpectedly deep, the bottom being red clay, with some Foraminifera.

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 1892

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References

page 461 note * See Map.

page 462 note * In marine charts the unit of distance is always the nautical mile, which is equal to one minute of arc of a great circle of the globe, and it is subdivided into 10 cables of 100 fathoms each; so that the nautical mile is 1000 fathoms. Hence, in applying the decimal system to geographical measurements, the fathom is the natural unit so long as we retain the subdivision of the circumference of the circle into degrees and minutes as at present. The metre and kilometre are very inconvenient and clumsy in this respect.

page 474 note * Proc. Roy. Soc. Edin., 1876, vol. ix. p. 287Google Scholar.