iS13.] a Chemical Knowledge of Manganese. 173 



When I considered the principle on which Gehlen founded 

 his method of separating iron from manganese by means of 

 succinic acid, namely, the insolubility of one of the two result- 

 ing compounds, it occurred to me that oxalic acid, or any f 

 its neutral salts, might be used for the same purpose, 

 more economy. with 



With this view I mixed a saturated muriatic solution of man- 

 ganese with some nitric acid, evaporated it to the consistence of 

 a thick syrup, diluted it with much water, saturated the excess 

 of acid with some potash, and left in the solution, for 24- hours, 

 a polished plate of iron, in order to separate the copper which 

 it contained as completely as possible. The solution being now 

 filtrated, I dropped intoit alitlle morepotash, to occasion a com- 

 mencement of precipitation. The solution, thus rendered a 

 little muddy, was treated with a neutral solution of oxalate of 

 potash as long as any iron continued to pricipitate. The vessel 

 was then kept for 24- hours in a moderate heat, to enable the 

 precipitate the better to separate from the liquid. The solution 

 contained lead (as was before mentioned). This was easily 

 thrown down by means of sulphate of soda, and the resulting 

 sulphate of lead was reduced upon charcoal by means of the 

 blowpipe. 



When the process described in the lastparagraph isattentively 

 observed, we find that the peculiar yellowish red or brownish 

 colour which the solution of manganese containing iron or mu- 

 riatic acid at first has, gradually disappears in proportion as the 

 iron is precipitated. W T hen the liquid is concentrated, indeed, 

 it assumes a peach blossom red colour: but when diluted, it 

 becomes as colourless as water. 



When prussiate of soda is dropped into the solution, the oxide 

 of manganese, when no copper happens to be present, is thrown 

 down of a snow-white colour, which does not change, though 

 left exposed to the air for days. Infusion of nutgalls occasions 

 no precipitate. When the solution contains copper, the precipi- 

 tate is peach blossom red, or crimson red, according to the pro- 

 portion of that metal present. When the least quantity of any 

 solution containing iron is dropped in, the precipitate has 

 always a shade of blue. 



To free the oxide of manganese completely from copper, 

 which is not fully accomplished by the preceding treatment with 

 iron, it is not sufficient to precipitate the oxide with carbonate of 

 ammonia, and to digest the precipitate in liquid ammonia. The 

 affinity between the oxides of copper and manganese is so great 

 tli it they cannot be separated from each other by means ot am* 

 niuiiia. Even after repeating this process four times successively 

 upon the same oxide, 1 found that it still retained a portion of 



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