and Littoral Manganese Nodules 177 



acetic acid, and sulphuretted hydrogen. In this way a minute 

 additional precipitate was obtained. The two precipitates 

 were dried, ignited, and dissolved together in hydrochloric 

 acid, and exactly the same process gone through again, so as 

 to get rid of all traces of manganese. The second two precipi- 

 - of cobalt and nickel sulphides were again dried, ignited, 

 redissolved in hydrochloric acid, the solution evaporated to 

 dryness, the residue taken up with water, and this solution 

 filtered. The nickel and cobalt in the nitrate were then precipi- 

 tated 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 O 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 i 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 hydro- 

 chloric 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 O 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 



el as NiO. The nickel and cobalt precipitates were aft. r- 

 wards tested in the dry way. 



B. Ill 



