, -MANGANESE. 



if thf.ir arlion is aided by heat; with other acids, it 

 is necessary to iidd a little o;irbon;icroi)s matter, as 

 sugar, to abstract a portion of oxygen from the per- 

 oxivle. Tlie principal salt is the sulphate of manga- 

 nese, which may be thus prepared : the acid acts 

 very slowly on the metal itself; if diluted, however, 

 it acts more quickly, hydrogen gas being disengaged 

 of a fetid smell. The solution, when concentrated, 

 is of a rose colour ; when obtained neutral, it affords 

 on evaporation, granular crystals of a reddish colour, 

 tnm>parent and soluble. Its taste is styptic and 

 bitter, and it is very soluble in hot water. Nitrate 

 of manganese may lie formed from the carbonate. It 

 is very soluble, and difficult to crystallize. It may 

 also be formed by making the acid act on a mixture 

 of peroxide of manganese and sugar or gum ; the 

 vegetable substance serving to reduce the manganese 

 to a minimum of oxidizement, while much carbonic 

 acid is evolved. The muriatic acid is equally incap- 

 able of combining directly with the black oxide, but 

 according to the usual law, it de-oxidates it : one 

 part of the muriatic acid is decomposed ; its hydro- 

 gen combines with the excess of oxygen of the black 

 oxide, to form water ; the chlorine, the other element 

 of this portion of the acid, is evolved ; and the rest 

 of the muriatic acid unites with the protoxide of 

 manganese, to form the muriate. The solution of 

 muriate of manganese is of a rose colour when con- 

 centrated, and affords, by evaporation, small crystals 

 of a pale rose colour, which are four-sided tables ; 

 they are deliquescent, very soluble in water, and, by 

 a red-heat, are converted into a red chloride. Car- 

 bonate and phosphate of manganese may be formed 

 by double decomposition, being thrown down in the 

 state of insoluble precipitates. The salts of manga- 

 nese suffer decomposition from the alkalies, which 

 precipitate the oxide: they are not decomposed, 

 however, by the inflammables, or the other metals, 

 which is a proof of the affinity of manganese to 

 oxygen. Oxide of manganese combines with those 

 earths capable of vitrification, and with their com- 

 pounds, and communicates to the glasses which they 

 form a violet tinge; it imparts the same colour, also, 

 to borax, and other verifiable salts. When heated 

 with these fluxes, by the blow-pipe, the colour soon 

 disappears in the interior flame, from de-oxidation, 

 but appears again if a little nitre be added. Sitlphuret 

 of manganese was obtained by Berthier, by heating 

 the sulphate in a charcoal crucible; it was of a gray 

 colour and crystalline appearance. Manganese, 

 from its infusibility, does not combine readily with 

 many of the metals. It shows, however, consider- 

 able affinity to iron, occurring frequently combined 

 with it in nature. It is contained, also, in those ores 

 of iron which are best adapted to the fabrication of 

 steel, and is supposed to improve the quality of steel. 

 Gold and iron are rendered more fusible by a due 

 addition of manganese; and the latter metal is ren- 

 dered more ductile. Copper becomes less fusible, 

 and is rendered whiter, but of a colour subject to 

 tarnish. Manganese is applied to no use in its 

 metallic form. The black oxide is employed by the 

 chemist in preparing oxygen and chlorine gases. It 

 has long been used in the art of glass-making, to 

 counteract the green tinge communicated by the iron 

 contained in the materials an effect which it pro- 

 duces by yielding oxygen to the oxide of iron, and 

 bringing it to a high degree of oxidation; in a larger 

 quantity added to glass, it gives a purple colour. It 

 is also used to give a black colour to earthenware. 



Ores of Manganese. I. Gray manganese ore is 

 found in prismatic crystals, whose primary form may 

 be considered as a right rhombic prism of 100 and 

 80. It also cleaves parallel with both the diagonals 

 of this prism. The crystals are usually slender and 



much striated, longitudinally. Fracture uneven ; 

 lustre metallic; colour dark steel-gray to iron-black; 

 streak brownish-black; opaque; brittle; hardness 

 about that of limestone; specific gravity, 4'626; it 

 also occurs in twin crystals, in reniform, botryoidal, 

 and other imitative shapes, with a surface generally 

 rough and drusy; composition columnar, of various 

 sizes of individuals, often forming a second granular 

 composition. In the massive varieties, the granular 

 or columnar composition often becomes impalpable, 

 in which cases the fracture is earthy. Gray man- 

 ganese ore has been divided into several sub-species, 

 chiefly in consequence of its mechanical composition. 

 Radiated gray manganese ore comprises long acicular 

 or reed-like prisms, and such massive varieties as 

 consist of columnar particles of composition, while 

 the foliated one refers to short prisms and granular 

 compositions. Compact gray manganese ore con- 

 tains varieties composed of impalpable granular in- 

 dividuals, and earthy gray manganese ore, such as 

 have lost their coherence, and appear in the state of 

 an earthy powder. The composition of some varieties 

 belonging to this species, has been found by Klaproth 

 to be 



Black oxide of manganese, 90-50 89'00 

 Oxygen, 2'?5 I0'25 



Water, 7'00 '50 



It is infusible before the blow-pipe, and colours glass 

 of borax violet blue. It is insoluble in nitric acid. 

 In heated sulphuric acid, it disengages oxygen; and 

 chlorine is evolved, if it is brought into contact with 

 muriatic acid; also, before the blow-pipe, or alone in 

 a strong heat, it gives out oxygen. The gray man- 

 ganese ore frequently accompanies the haematitic 

 iron ores; and sometimes its earthy and compact 

 varieties constitute beds by themselves. It also 

 occurs in veins, particularly in porphyry, along with 

 sulphate of barytes. Its most celebrated localities 

 are Ihlefield in the Elartz, and (Ehrenstock in Thu- 

 ringia. It has numerous localities also in Saxony, 

 Bohemia, Hungary, France, and Britain. It has 

 been observed in many of the American states; but 

 occurs most abundantly in Vermont, at Bennington 

 and Monkton, accompanied with haematite and un- 

 cleavable manganese ore. The uses of this species 

 of manganese ore, wherever it occurs in quantity, are 

 very important for various chemical operations, and 

 for none more so than the manufacture of chloride of 

 lime, the ordinary bleaching powder. Its use in the 

 manufacture of glass, is also very considerable. 

 Black wad deserves to be mentioned under this 

 species, as a very remarkable substance among those 

 which contain manganese. It occurs in reniform, 

 botryoidal, fruticose, and arborescent shapes, in froth- 

 like coatings, on other minerals, or massive. Its 

 composition is generally impalpable, and the fracture 

 even or earthy. Colour brown, of various shades; 

 opaque; very sectile; soils and writes; hardness be- 

 low that of talc; specific gravity, 3.7; the varieties 

 are very light, when dry; yet, as they imbibe water 

 with violence, when immersed into it. they sink im- 

 mediately. Mixed with linseed oil, it undergoes a 

 spontaneous combustion. It consists of 



Oxide of manganese, 



iron, 



Water, 

 Carbon, 

 Baryta aud silica, 



6-50 

 1750 



mo 



9'OU 



It has been found in the Hartz, in Devonshire, and 

 Cornwall, in England, also at one locality in the 

 United States, in Connecticut. The black wad is 

 conceived to be the colouring matter in the dendritic 

 delineations upon steatite, limestone, and other sub- 

 stances. 



2. Pyramidal manganese ore is a rare mineral, 



