and Littoral Manganese Nodules 165 



III. A piece of a horizontally stratified concretion, with 

 botryoidal upper surface. It was 15 millimetres thick. 



Samples marked IV and V are from one nodule. IV is part 



of the outer rind, 13 millimetres thick, consisting of concentric 



rs, most of them mottled with reddish yellow spots, and 



separated by fine seams of purple-brown oxide of manganese, 



without yellow specks. V is the kernel of the same nodule. 



- harder than the rind, from which it easily splits away. 



It i- nearly spherical, with a radius of 16 millimetres. At the 



centre is a small colourless piece of mineral matter. 



This nodule was one of an enormous haul made by x the 



illenger" on the I2th July 1875 in the North Pacific, in 



lat- 37 5 2 ' ^-. l n g- I 6o 17' W. The depth of the water was 



2740 fathoms. The temperature of the bottom water was 



C., and its density at 15-56 C. was 1-02573. The gaseous 



contents of the water were 17-7 c.c. mixed nitrogen and 



oxygen, of which 16-95 per cent, was oxygen, and 21-48 c.c., 



or 42 milligrammes, carbonic acid per litre. It will be seen 



that the water contains very much less oxygen than was 



contained in the bottom water off the Australian coast. In 



water the dissolved oxygen has been reduced to 



almost exactly half the amount which it contained when it 



r he surface. All over this distri< t, where manganese greatly 



abounds, the dissolved oxygen has been reduced from 34 per 



of the mixed gases, as at the surface, to from 16 to 22 



per cent, at the bottom. 



The position of this station lies midway between the 



mds and the Sandwich Islands, being 1000 miles 



nearest island of either group ; it is 1600 miles 



nearest point of tin- N< >it h Americ. < nt 



in t e latitude. Hener. although there were i; 



;mm laml than tin-, it can claim to be quite 

 beyond the rea< ! .ntin -ntal influence. The st.i 



ich samples I, II, and HI come, although comparativeK 

 close to t may be said also to be pi 



bey< ^phere of it- rntlu. -ncc, as, owing to it- . liinate, it 



'most destitute of drainage. 



>ral NoduUs, samples Af, N, P, Q, K 



