CHROMIUM, MOLYBDENUM, TUNGSTEN URANIUM, ETC. 309 



limit ourselves to illustrating the chemical character of manganese by 

 describing the metal and its corresponding acids. The fact alone that 

 the oxides of manganese are not reduced to the metal when ignited in 

 hydrogen (whilst the oxides of iron give metallic iron under these 

 circumstances), but only to manganous oxide, MnO, shows that 

 manganese has a considerable affinity for oxygen that is, it is difficult 

 to reduce. This may be effected, however, by means of charcoal or 

 sodium at a very high temperature. A mixture of one of the oxides of 

 manganese with charcoal or organic matter gives fused metallic man- 

 ganese under the powerful heat developed by coke with an artificial 

 draught. The metal was obtained for the first time in this manner by 

 Gahn, after Pott, and more especially Scheele, had in the last century 

 shown the difference between the compounds of iron and manganese 

 (they were previously regarded as being the same). Manganese is pre- 

 pared by mixing one of its oxides in a finely-divided state with oil and 

 soot ; the resultant mass is then first ignited in order to decompose 

 the organic matter, and afterwards strongly heated in a charcoal crucible. 

 The manganese thus obtained, however, contains, as a rule, a consider- 

 able amount of silicon and other impurities. Its specific gravity varies 

 between 7-2 and 8'0. It has a light grey colour, a feebly metallic 

 lustre, and although it is very hard it can be scratched by a file. It 

 rapidly oxidises in air, being converted into a black oxide ; water acts 

 on it with the evolution of hydrogen this decomposition proceeds very 

 rapidly with boiling water, and if the metal contain carbon. 20 



dioxide, as was mentioned above. Manganous nitrate also leaves manganese dioxide 

 when heated to 200 It is also obtained from manganous and manganic salts of the 

 alkalis, when they are decomposed in the presence of a small amount of acid ; the prac- 

 tical method of converting the salts MnX 2 into the higher grades of oxidation is given in 

 Chapter II., Note 6. 



20 Other chemists have obtained manganese by different methods, and attributed 

 different properties to it. This difference probably depends on the presence of carbon 

 in different proportions. Deville obtained manganese by subjecting the pure dioxide, 

 mixed with pure charcoal (from burnt sugar), to a strong heat in a lime crucible until the 

 resultant metal fused. The metal obtained had a rose tint, like bismuth, and like it 

 was very brittle, although exceedingly hard. It decomposed water at 'the ordinary 

 temperature. Brunner obtained manganese having a specific gravity of about 7'2, which 

 decomposed water very feebly at the ordinary temperature, did not oxidise in air, and 

 was capable of taking a bright polish, like steel ; it had the grey colour of cast iron, was 

 very brittle, and hard enough to scratch steel and glass, like a diamond. Brunner's 

 method waa as follows , He decomposed the manganese fluoride (obtained as a soluble 

 compound by the action of hydrofluoric acid on manganese carbonate) with sodium, by 

 mixing these substances together in a crucible and covering the mixture with a layer of 

 ealt and fluor spar , after which the crucible was first gradually heated until the reaction 

 began, and then strongly heated in order to fuse the metal separated. Glatzel (1889) 

 obtained 25 grms. of manganese, having a grey colour and sp. gr. 7'39, by heating a 

 mixture of 100 grms. of MuClj with 200 grms. KC1 and 15 grms. Mg to a bright white 

 heat. Moissan and others, by heating the oxides of manganese with carbon in the electric 



