148 Intelligence and Miscellaneous Articles. 



solved in muriatic acid without evolving any gas : nevertheless it 

 was not protoxide of iron, but a mixture of protoxide and per- 

 oxide, as was ascertained by the increase of weight which it ac- 

 quired by calcination in the air. The solution of this substance in 

 muriatic acid is yellow ; when ammonia is added to it, a black pre- 

 cipitate is formed, which appears brown when it is more divided : 

 it may be filtered and washed in the air without any change of 

 colour, that is to say, without becoming a hydrate of the peroxide, 

 as might be expected. After drying, the precipitate is in small 

 brittle pieces of a black-brown colour, and of a deep brown when 

 powdered: it is a hydrate of a compound of the protoxide and 

 deutoxide, becoming black and losing its water by heat. 



This hydrate possesses another unexpected property, — that of 

 being attracted by the magnet as strongly as the intermediate com- 

 pound, or the magnetic iron ore. If a magnet be immersed in the 

 liquid, while the precipitate is in a state of suspension, a great part 

 of it is collected round the magnet. 



Magnetic iron ore acts in a precisely similar way to the artificial 

 substance just described. Some crystals of it were dissolved in 

 muriatic acid, without the contact of air, and the yellow solution 

 was precipitated by ammonia. The same biack precipitate was 

 obtained, which did not oxidize more in the air, and was equally 

 magnetic. It is well known that the white precipitate formed by 

 an alkali in a solution of a protosalt of iron becomes black when 

 it is boiled in the liquid, and it was apparently admitted that this 

 precipitate was anhydrous protoxide of iron: this is a mistake, for 

 it is also a hydrate of the protoxide and peroxide formed by contact 

 of the air during ebullition. 



The wliite protohydrate of iron is not magnetic, at least while it 

 remains in the liquid. This fact appears surprising, if it be admit- 

 ted that in the niagn^itic compounds of oxides of iron the property 

 of being attracted depends upon the quantity of protoxide which 

 they contain. Reasoning in this way, the hydrate of the protoxide 

 ought to be more magnetic than the hydrate of the mixed oxides. 



METHOU OF OBTAINING PROTOXIDE OF MANGANESE. BY THE 

 SAME. 

 By Arfwedson's method, which consists in lieating carbonate of 

 manganese in hydrogen, the protoxide is obtained in a certain and 

 easy manner: it would therefore he useless to describe the following 

 method, if, while it is as easy, it had not also the advantage of pro- 

 ducing a protoxide which is unalterable in the air at common tem- 

 peratures. This method consists in heating together fused chloride 

 of manganese and carbonate of soda, and fusing the mixture at a 

 red heat : when the mass is treated with water, protoxide of man- 

 ganese is obtained, of a greenish-gray colour. 



ON THE REDUC'i'ION OF NICKEL. BY THE SAME. 



Richter, as is well known, placed nickel among the noble metals, 

 because he found that its oxide was reduced by the heat of a porce- 

 lain 



