and Littoral Manganese Nodules 175 



about 2 grams were required. This was added in a state of 

 cream to the liquid in a small flask. The flask was corked and 

 allowed to stand some hours, being shaken occasionally. The 

 liquid was then filtered off, and the precipitate, after thorough 



ling, tested for manganese with carbonate of soda on 

 platinum foil. 



D. To the filtrate from the carbonate of baryta precipitate 

 excess of sodium acetate was added, so that there should be 

 not less than 3C 2 H 4 O 2 to HC1 in the solution (in practice 15 to 

 20 c.c. of a i in 10 solution of NaA were added). Before adding 

 the acetate it is well to drop in a little acetic acid, otherwise 

 an immediate precipitation of barium salt occurs. Bromine in 

 excess was then added to the sufficiently dilute fluid, and the 

 flask corked and placed in a moderately warm place for some 

 time. Gentle warming at first greatly aids the precipitation 

 of the MnO 2 . When the manganese had begun to deposit, 

 and the liquid in the flask was at a temperature of about 50 C., 

 it was removed to a colder place (at the ordinary temperature 

 of the room), and allowed to stand over-night. If necessary, 

 a little more bromine was first added; this is regulated by 

 practice. Next day the flasks were heated in order to drixv 

 off all superfluous bromine, a few drops of alcohol being added 

 towards the end to get rid of the last traces. \Vlu-n the solution 

 became perfectly colourless it was filtered, all the MnO 2 that 

 came easily out of the flask being thrown on the filter and 

 washed witli boiling water. The filtrate was tested first for 

 more MnO 2 with NaA and bromine, and then for nickel and 

 copper (vide below). 



(a) The filter, on which was the bulk of the MnO 2 precipi- 

 tate, was dried. When dry. tin- MnO., was returned to the 



n.il tla-k (on the sides of which some MnO 2 remained 

 sticking), the filter wa- i-nit< <!. ami its ash also dropped into 

 tin- tlask. 1 In- manganese precipitate was then dissolved in 

 a few drops of HI, tin- chlorine boiled off, and the 



solution s]i-htlv diluted. It was found that the Mn<) 2 always 



itfht down sonic l>ar\ta with it. and this was separated by 

 precipitation with a few drops of sulphuric acid. This solution 



tin -n filtered from the BaSO 4 ; evaporated to dryness over 



