No. 9. [From Trans. Roy. Soc. Edin., Vol. xxxvr. 

 Part 2, 1891, p. 459.] 



ON THE COMPOSITION OF OCEANIC AND 

 LITTORAL MANGANESE NODULES 



THE following analyses were made some years ago, princi- 

 pally 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 

 i;,th March 1874, in lat. 42 42' S., long. 134 10' E. The 

 h of the water was 2600 fathoms, and the temperature of 

 the bottom water 0*2 C. The density of the bottom water 

 1-02570 at 15*56 C. Being from a high southern latitude, 

 and therefore near the source of surface aeration, the water is 

 <-d with atmospheric gases, especially oxygen. 

 >ntained, per litre, 18-4 c.c. of mixed nitrogen and oxygen, 

 hi< h 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 

 i coast, and about 500 miles west of Tasmania. 

 It was the deepest water observed in the Ant n tic voyage 

 vcen the Cape of Good Hope and Melbourne. The haul was 

 iiunlant <mr. and a few notes which I made at tlir 

 I r was found unexpectedly 



i being red clav. with some For.mnmf. ri Tin- 

 nr up quite full of thi- inu-1. with m.mv 

 .1 large number of manganese nodules. These were 

 11 shapes, .mil with thr < 1 ^tic mammillatcd surface, 



whirh in Mmr was acc< to such a degree as to give 



I il appe.i kc specimens of Psilomelane. 



v of them were perfectly spherical, others formed groups 



ii- 



