COMPOSITION OF OCEANIC AND LITTORAL MANGANESE NODULES. 469 



nickel and cobalt in the filtrate were then precipitated by a few drops of pure caustic 

 potash. This precipitated the nickel and cobalt together. The precipitate was ignited 

 and weighed as NiO + Co 3 4 . It was then again dissolved in hydrochloric acid, all excess 

 of acid evaporated off, the residue taken up with water, the solution filtered into a small 

 beaker, and gently evaporated down. During this evaporation very often a minute 

 quantity of silica and ferric hydrate came down, and the solution had to be refiltered. 

 After the liquid became very concentrated — reduced to a few drops, in fact — the cobalt 

 was precipitated as double nitrite of cobalt and potassium. A solution of 1 in 4 nitrite 

 of potassium was used. 



(a) The cobalt precipitate, after being filtered off and washed with acetate of soda, 



was dissolved in water or dilute hydrochloric acid, the filter ignited, and the 

 ash added to the solution. The solution was evaporated to dryness, water 

 added, and the solution filtered. The cobalt was then precipitated by caustic 

 potash solution. It was ignited to Co 3 4 . 



(b) To the filtrate from the potassium nitrite precipitate excess of hydrochloric acid 



was added, the solution evaporated, and the nickel precipitated by caustic 

 potash. It was found necessary to redissolve this nickel precipitate and 

 reprecipitate it, on account of the relatively very large quantity of potassium 

 chloride which had to be washed out of it. This gave the nickel as NiO. 

 The nickel and cobalt precipitates were afterwards tested in the dry way. 



Tabular List of Nodules submitted to Analysis. 

 Oceanic Nodules — 



Nos. I., II., and III. are from a locality 400 miles south of the Australian coast, in 

 lat. 42° 42' S., long. 134° 10' E. Depth, 2600 fathoms. I. is from the outer 

 rind of a large spherical nodule, and it was detached without any trace of the 

 kernel. II. is a similar piece taken from the outside shell of a smaller spherical 

 nodule, with traces of an augitic kernel. III. is a piece of a horizontally- 

 stratified nodule with botryoidal upper surface. 



Nos. IV. and V. are from the same nodule, which was collected on the 12th July 

 1875 in the North Pacific in lat. 37° 52' N., long. 160° 17' W. Depth, 

 2740 fathoms. IV. is a portion of the outer shell, 13 millimetres thick, 

 consisting of concentric layers, most of them mottled with reddish-yellow 

 spots. V. is the kernel of the same nodule, and is harder than the rind, from 

 which it easily splits away. It was nearly spherical and with 16 millimetres 

 radius. At the centre was a small colourless piece of mineral. 



Littoral Nodules — 



These are all from Loch Fyne in 104 fathoms (see page 3). M, N, P, and Q are 

 separate selected nodules ; K and R are the kernels and rinds of five nodules. 



