MANGANESE. This name is gene rally given to a black mineral, originally described in the year 1774, by Scheele, as a peculiar earth, and which was after wards shown by Galin to be the oxide of a metallic substance which he called magnesium. This term, however, having been applied to the metallic base of mag nesia, the word manganese has been adopted to designate the metal, and the ore above alluded to has been called black, or peroxide of, manganese. The metal itself has a specific gravity of about 8. It is gray, hard, brittle, and very dif ficult of fusion, and has not been applied to any use. The black oxide, on the contrary, is largely employed as a source of oxygen, and is especially important from the use which is made of it in the decomposition of common salt for the production of chlorine. Manganese may be represented by the equivalent 28; and the black oxide, being a compound of 1 atom of 'manganese and 2 of oxygen, has the equivalent 44 (28 + 16). There is also a protoxide of manganese, com posed of 28 metal + 8 oxygen, which is the basis of the salts of this When hydrate or carbonate of potassa, or nitre, are fused with peroxide of man ganese m an open vessel, a dark-colored compound is obtained, long known under the name of chameleon mineral, in conse quence of its yielding in cold water a so lution which is at first green, then blue, purple, red, brown, and ultimately de o sits a brown powder, and becomes color less. This substance has since been termed manganate potash, and has been prmecl to contain a compound of 1 atom of manganese and 8 of oxygen, which has been called manganie acid, and is represented by the equivalent 52. In the pink solution, which is produced at once by the action of hot water, man ganese exists in a still higher state of ox idizement, forming the per-manganie acid, in which 2 atoms of manganese are combined with 7 of oxygen. Both these compounds are very easy of decompo sition. Some of the proto-salts of man ganese have lately been used in calico printing as the source of brown colors, and occasionally as deoxidizing agents. The black oxide of manganese occurs abumlantly in Vermont at Bennington and Monekton, accompanied with limma tite. Black wad is only found in Con necticut. Phosphate of manganese is met with at Washington, Ct. Sulphuret of manganese is found in New-York.
Manganese is found native combined with iron, and when added artificially to steel it improves the quality. Gold and iron are rendered more fusible by its ad dition, and the iron becomes more duc tile. Copper becomes whiter, less fusi ble, and more liable to tarnish. The most extensive use of oxide of manga nese is in bleaching to produce chlorine, and it is often desirable to test the value of these ores.
M. Gay Lussac has proposed to deter mine the commercial value of manganese ore by the quantity of chlorine which it affords when treated with liquid muri atic acid. He places the manganese powder in a small retort or mattress, pours over it the acid, and the chlorine being disengaged with the aid of a gen tle heat, is transmitted into a vessel con taming milk of lime or potash water.
This liquor is thereafter poured into a dilute solution of sulphate of indigo; and the quantity of chlorine is inferred from the quantity of the blue solution which is decolored.
This mode of testing is easily under stood. When muriatic acid is anted on by manganese ore, the black oxide in it yields up one equivalent of its oxygen, and becomes reduced to the condition of protoxide of manganese : the atom of oxygen seizes on the equivalent of hy drogen in the muriatic acid, and sets the chlorine, the other element of the acid, free ; and thus for every one atom of manganese present one atom of chlorine is liberated. if the amount of the latter is determined, it of course represents the weight of manganese.
The manuflicturer of flint glass uses a small proportion of the black manganese ore, to correct the green tinge which his glass is apt to derive from the iron pre sent in the sand he employs. To him it is of great consequence to get a native manganese containing as little iron oxide as possible; since in filet the color or limpidity of his product will depend alto gether upon that circumstance.
. Sulphate of manganese has been of late years introduced into calico-printing, to give a chocolate or bronze impression. It is easily formed by heating the black oxide, mixed with a little ground coal, with sulphuric acid. (See CALICO-PRINT /No.) The peroxide of manganese is used also in the forMation of glass pastes, and in making the black enamel of pottery. MANGLE is a machine for pressing heavy linen after washing. The linen, &c., is wrapped round rollers, and these ire passed and forward, under a heavily-loaded case. The best are those in which the winch turns but one way, the motion being reversed in the geer when the case has run home.
An improved mangle has been made by which linen may be both ironed and mangled at the same time. It is worked by a moving table, which passes under a pressure of 11 ton ; and the operation may be performed by a child of eight or nine years old. The machine does not occupy a space of more than eight super ficial feet, and the weight of the whole is not more than 2 cwt. A good mangle is now made by three heavy rollers laid vertically : a winch handle works the in termediate one, and the upper is pressed down by a screw to any desired amount of pressure.