DKUTOXIDE OF MANGANESE. 533 



once by passing the cloth through a solution of chloride of lime. 

 The colour thus produced is called manganese brown. 



Crystallized under 42, the sulphate of manganese gives crys- 

 tals containing 7 HO, which have the same form as sulphate of 

 iron. The crystals which form between 45 and 68, contain 

 5HO, and are isomorphous with the sulphate of copper. By a 

 higher temperature, from 6'8 to 86, a third set of crystals are 

 obtained, which contain 4 HO, their form is a right rhombic 

 prism. The sulphate of iron and other sulphates also assume the 

 same form (Mitscherlich). This salt loses 3 HO at 240, but 

 retains 1 eq. even at 400, like the other magnesian sulphates. 

 M. Kuhn finds, that when a strong solution of the sulphate of 

 manganese is mixed with sulphuric acid and evaporated by heat, 

 a granular salt is precipitated, which contains only one equiva- 

 lent of water. This sulphate also forms a double salt with sul- 

 phate of potash, which contains 6HO. The anhydrous salt is 

 soluble, according to Brandes, in 2 parts of water at 59, in 1 

 part at 1 22 ; but above the latter term, the salt becomes less 

 soluble. It is insoluble in alcohol. 



Hyposulphate of manganese (page 335), is obtained by 

 evaporation as a deliquescent saline mass. The peroxide of 

 manganese used in preparing it, should be previously treated 

 with nitric acid, to dissolve out the hydrated oxide, and be 

 well washed. The oxalate of manganese, is a highly insoluble 

 salt. The acetate is soluble in 3i parts of cold water, and also 

 in alcohol. The bitartrate of potash dissolves protoxide of 

 manganese, and forms a very soluble double salt, the tartrate 

 of potash and manganese, which can be obtained, although with 

 difficulty, in regular crystals. 



Deutoxide of manganese, Manganic oxide ; Mn 2 O 3 ; 991.8 or 

 79.44. This oxide is left of a dark brown, almost black colour, 

 when the nitrate of the protoxide is gently ignited. It also 

 occurs crystallized in the mineral kingdom, although rarely; its 

 density is 4.818, and it is named braunite as a mineral species. 

 The hydrate of manganic oxide is formed by the oxidation in 

 air of the manganous hydrate. The manganic hydrate also fre- 

 quently occurs in nature of a black colour, both crystallized and 

 amorphous, and is often mixed with the peroxide of manganese. 

 It constitutes the mineral species manganite, of which the den- 

 sity is 4.3 to 4.4, and the formula Mn 2 O 3 , HO. This oxide 



