MAN 



MAN 



into powder, which is found to have ac- 

 quired considerable addition to its weight. 

 But when heated in the open air, it passes 

 more rapidly through the different chang- 

 es of colour in proportion as it combines 

 with oxygen, to the absorption of which 

 these changes are owing : hence manga- 

 nese, like some other metals, combines 

 with different portions of oxygen, forming 

 with it different oxides. The different 

 coloured oxides are combined of man- 

 ganese and oxygen in the following pro- 

 portions : 



Manganese 

 Oxygen . . 



White 

 Oxide. 



. .80 



. .20 



100 



Brown or 

 Red Oxide. 



74 

 26 



100 



Black 

 Oxide. 



60 

 40 



100 



From the black, which is most abun- 

 dant in oxygen, the chemists usually ob- 

 tain what they use in their experiments. 

 The black is evidently the metal at the 

 maximum of oxydizement, the white is 

 the one at the minimum. Manganese 

 does not enter into combination with 

 azote, hydrogen, or carbon. By means 

 of charcoal the oxide is reduced, by being 

 deprived of its oxygen. Phosphorus com- 

 bines very readily with manganese, form- 

 ing' a phosphoret. It may likewise be 

 made to combine with sulphur, forming 

 a suiphurct. It enters into combination 

 with the acids, and forms salts with them. 

 These salts may be decomposed by the 

 alkalies, which throw down precipitates 

 of a yellow or reddish colour. None of 

 them are decomposed by a>y of the 

 other metals, which shews the strong 

 affinity of manganese to oxygen. The 

 pure alkalies favour the oxydation of 

 7nanganese, and the decomposition of 

 water, because they combine readily with 

 this oxide. When the black oxide is ex- 

 posed to heat, witit twice its weight of dry 

 soda or potash, a compound is formed of 

 a dark green colour, which is soluble in 

 water. During the solution, this sub- 

 stance exhibits rapid changes of colour, 

 and on that account has been denominat- 

 ed the " mineral camelion." There is no 

 action between manganese and any of 

 the earths ; but its oxide combines with 

 them, and forms vitreous matters, which 

 are of different colours, according to the 

 degree of oxydation of the manganese, 

 and its mixture with iron. The native 

 black oxide of manganese is applied to 

 several purposes. It is the substance 

 from which oxygen can be most econo- 



mically obtained, large quantities of 

 wliich are consumed in the formation of 

 the oxy -muriatic acid employed in the 

 art of bleaching. It is used in glass-mak- 

 ing, to remove from the substance the 

 green colour wliich is derived from the 

 oxide of iron. The theory of its action is 

 thus explained: iron, in a low state of 

 oxydizement, gives to glass a green tinge, 

 while, if it be at a high degree of oxy- 

 dizement, it either does not enter into 

 fusion with the ingredients of the glass, 

 or at least does not communicate any co- 

 lour. Manganese, in the state of black 

 oxide, gives a violet colour, but reduced 

 to the white oxide the glass is colourless. 

 In adding, therefore, the black oxide to 

 glass, while it yields its oxygen to the 

 iron, which it thus brings to "a high state 

 of oxydizement, it passes itself to the state 

 of wliite oxide, and thus each metal is in 

 that state in which it does not communi- 

 cate colour. The black oxide is also use- 

 ful, probably by consuming the carbona- 

 ceous matter and other substances pre- 

 sent in the materials which are suscepti- 

 ble of oxydizement. In large quantities 

 it is used in the composition of ornament- 

 al glass, to give a purple colour. It is like- 

 wise employed to give a black colour to 

 earthen ware, a quantity of it being mix- 

 ed with the composition before it is 

 baked. 



MANGIFERA, in botany, mango-tree, 

 a genus of the Pentandria Monogynia 

 class and order. Natural order of Tere- 

 bintacex, Jussieu. Essential character : 

 corolla five-petalled ; drupe kidney-form. 

 There are three species, of which M. in- 

 dica, mango-tree, is the most remarkable; 

 it is a large spreading tree ; the wood is 

 brittle, and used only for indifferent 

 works ; the bark becomes rugged by 

 age ; the leaves are seven or eight inches 

 long, and about two broad, terminating in 

 points, having several transverse parallel 

 opposite ribs ; the flowers are produced 

 in loose bunches at the ends of the branch- 

 es ; the fruit of this tree, when fully ripe, 

 is yellow and reddish, possessing a fine 

 agreeable juice; some are full of fibres, 

 the juice runs out of these on cutting; 

 but those without fibres are much the 

 finest, they cut like an apple, and are es- 

 teemed a very wholesome fruit ; except- 

 ing pine apples, they are preferable to 

 any other in India : in Europe we have 

 only the unripe fruit brought over in 

 pickle. 



MANIS, in natural history, a genus of 

 Mammalia, of the order Bruta. Generic 

 character : no teeth ; tongue round and 



