174? Contributions towards [Sept. 



copper ; for prussiate of soda always threw down a reddish pre- 

 cipitate. 



When the ammonia is evaporated, it soon acquires a blue 

 colour, in consequence of the copper which it contains. By 

 degrees a bluish white powder falls down, which is a triple com- 

 pound of carbonic acid, and the oxides of copper and manga- 

 nese. Carbonate of ammonia dissolves almost nothing of pure 

 carbonate of manganese ; but if copper be present, the latter 

 becomes at least partly soluble in the ammonia, but yet in such 

 a manner that a portion of the manganese is dissolved at the 

 same time. 



This separation of carbonateof copper-and-manganeseduring 

 the evaporation of the liquid, though I had previously endea- 

 voured to throw down the whole of the copper by means of an 

 iron plate, gave me considerable trouble. 



To obtain a complete separation of the copper from the oxide 

 of manganese, I threw down the whole oxides from the muriatic 

 solution by means of carbonate of ammonia, washed the preci- 

 pitate well with ammonia and water, and then dissolved it in 

 sulphuric acid. To this solution, previously rendered quite 

 neutral, I added a portion of carbonate of potash, or of ammo- 

 nia, digested the whole for some time, and then separated the 

 resulting precipitate, which consisted of oxides of copper and 

 manganese, by means of the filter. 



In this manner was the copper completely separated, which at 

 first, as I had convinced myself, precipitated in combination with 

 the oxide of manganese. The clear solution freed from the 

 precipitate was completely decomposed by carbonate of ammonia. 

 The precipitate washed and collected was considered as pure 

 carbonate of manganese, proper for chemical experiments; 

 for I had previously ascertained that the ore contained no 

 alumina. 



This carbonate of manganese, prepared and purified in the 

 manner above described, I employed in my experiments. 



II. Reduction of the Oxide of Manganese. 



The difficult fusion of this metal, and the property which it 

 has of running into a glass when the oxide is brought in contact 

 with a flux, or when the oxide employed for reduction comes in 

 contact with the sides of the vessel, for a long time prevented 

 chemists from supplying themselves with it in any quantity, and 

 from accurately determining its relation to other bodies, and the 

 proportion of oxygen with which it is combined, either in diffe- 

 rent native compounds or artificial products. 



Another inconveniency which occurs in the reduction of this 

 metal, and which is a consequence of its difficult fusibility, con* 



