MAG 



[273] 



M A L 



transition rocks. This ore is very 

 common in Sweden. 



MA'GNETISM. (magnttisme, Fr.) The 

 tendency of the iron towards the 

 magnet, and the power of the 

 magnet to produce that tendency ; 

 the power of attraction. Very 

 delicate experiments have shewn 

 that all bodies are more or less 

 susceptible of magnetism. Many 

 of the gems give signs of it ; tita- 

 nium and nickel always possess 

 the properties of attraction and 

 repulsion. But the magnetic agen- 

 cy is most powerfully developed in 

 iron, and in that particular ore of 

 iron called the loadstone, which 

 consists of the protoxide and per- 

 oxide of iron, together with small 

 portions of alumina and silica. A 

 metal is often susceptible of magne- 

 tism if it contain only the 130,000th 

 part of its weight of iron, a quantity 

 too small to be detected by any 

 chemical test. One of the most 

 distinguishing tests of magnetism is 

 polarity, or the property a magnet 

 possesses when freely suspended, of 

 spontaneously pointing nearly north 

 and south, and always returning to 

 that position when disturbed. In- 

 duction is the power which a mag- 

 net possesses of exciting temporary 

 or permanent magnetism in such 

 bodies in its vicinity as are capable 

 of receiving it. By this property 

 the mere approach of a magnet 

 renders iron or steel magnetic, the 

 more powerfully the less the dis- 

 tance. Iron acquires magnetism 

 more rapidly than steel, yet it loses 

 it as quickly on the removal of the 

 magnet, whereas the steel is im- 

 pressed with a lasting polarity. 



MAJO'LICA. A local name for a variety 

 of white compact limestone. 



MA'LACHITE. (malachite, Fr malachite, 

 It.) Green carbonate of copper. 



M'ALACOLITE. A variety of augite, of 

 a darkish green colour. 



MAXACOPTE'EYGII. (from /iaXa/co?, 

 soft, and Tnepov, a wing or fin, Gr.) 



One of the two great orders into 

 which Cuvier divided all bony 

 fishes. The rays of the fins are thin, 

 flexible, articulated, and branched; 

 each ray somewhat resembles a 

 jointed bamboo, with this difference, 

 that what veins a single ray at 

 bottom, branches out into three or 

 four rays atop. The gold-fish 

 serves as a familiar illustration of 

 this order. 



MALACOPTE'BYGIONS. Soft finned ; 

 belonging to the order Malacop- 

 terygii. 



MALACO'STRACAN". An order of Crus- 

 taceans, distinguished by having 

 sessile eyes, imbedded in the 

 substance of the head. 



MALACTI'NIA. The name of a class of 

 animals belonging to the order 

 Cyclo-neura or radiata. These are 

 soft, free, aquatic animals, of a 

 simple structure, entirely marine, 

 generally of a transparent gela- 

 tinous texture, and radiated struc- 

 ture or form, luminous, and 

 emitting an acrid secretion from 

 their surface, which is capable of 

 irritating and inflaming the human 

 skin like the sting of a nettle. 



MALLEABILITY. (malleabiliU, Fr.) 

 The property or capability of being 

 hammered into different forms with- 

 out breaking. 



MA'LLEABLE. (malleable, Fr. malled- 

 lile, It.) That may be spread out 

 by hammering. Of all the metals, 

 the most malleable is gold, five 

 grains of which may be hammered 

 out so as to cover a surface of 273 

 square inches, the thickness of the 

 leaf not exceeding 282020^- of an inch. 



MA'LLEUS. (malleus, Lat. a hammer.) 



1. One of the bones of the ear, 

 ' thus named from its supposed re- 

 semblance to a hammer. 



2. A bivalve shell of the family 

 Malleacea. 



MALM KOCK. The name given to a 

 variety of firestone, a member of 

 the chalk series. 



MA'LTHA. A variety of bitumen j 



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