MET 



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MET 



copper ; those of Loweswater, Bor- 

 rowdale, Patterdale, and Caldbeck 

 fells yield lead, or lead and 

 copper." 



METALLI'FEEOUS. (from metallum, 

 metal, and/m>, to produce.) Yield- 

 ing metal; as metalliferous deposits, 

 metalliferous districts, metalliferous 

 veins, metalliferous dykes, &c. 



META'LLUEGY. (from fj^Ta\\ov, a 

 metal, and ep<yov, a work, Gr. 

 mbtallurgie, Pr.) Some authors 

 comprehend under this term, the 

 whole art of working metals, from 

 the glebe, or ore, to the utensil ; 

 in which sense assaying, smelting, 

 refining, parting, smithery, gilding, 

 &c., are only branches of metal- 

 lurgy. Others restrain metallurgy 

 to those operations required to sep- 

 arate metals from their ores. 



METAMO'BPHIC. (from fie, trans, 

 and popcjtri, forma, Gr.) A term 

 proposed for such hypogene rocks 

 as are stratified, or altered by strat- 

 ification ; any stratified primary 

 rock may be termed metamorphic. 

 By some authors the metamorphic 

 rocks have been divided into two 

 groups ; namely, those which pre- 

 sent traces of stratification, and, 

 secondly, those which present no 

 appearance of regular arrangement, 

 but occur in amorphous or shape- 

 less masses. The term metamor- 

 phic has been assigned by Sir C. 

 Lyell to a certain division of rocks 

 comprising the crystalline strata or 

 schists, called gneiss, mica schists, 

 clay slate, chlorite schist, marble, 

 and the like, the origin of which is 

 more doubtful than that of the 

 other divisions. The metamorphic 

 rocks are either those in which the 

 original structure and composition 

 are still obvious, or those in which 

 those characters are altogether 

 obscured and replaced by others, 

 produced either by heat, or pressure, 

 or both conjoined. The metamor- 

 phic rocks may be divided into two 

 sub-groups, those in which the 



original mineral structure is still 

 recognizable, the particles, however 

 altered, not having entered into 

 new combinations, and those where 

 such new combinations have been 

 effected. Jukes. 



METAMO'RPHOSIS. (fierafiop^wffi^, Gr. 

 change into another form, metamor- 

 phose, Fr. metamdrfosi, It.) Trans- 

 formations which insects undergo 

 previously to their arriving at their 

 state of perfection. The progress 

 of metamorphosis of insects is most 

 strikingly displayed in the history 

 of the Lepidopterous, or butterfly 

 and moth tribe. The egg, which 

 is deposited by the butterfly, gives 

 birth to a caterpillar; an animal 

 which, in outward shape, bears not 

 the slightest resemblance to its 

 parent, or to the form it is itself 

 afterwards to assume. It has, in 

 fact, both the external appearance, 

 and the mechanical structure, of a 

 worm. But these vermiform in- 

 sects contain in their interior the 

 rudiments of all the organs of the 

 perfect insect. These organs are, 

 however, concealed from view by a 

 great number of membraneous cov- 

 erings, which successively invest 

 one another, like the coats of an 

 onion, and are thrown off, one after 

 another, as the internal parts are 

 gradually developed. These suc- 

 cessive peelings of the skin are but 

 so many steps in preparation for a 

 more important change. A time 

 comes when the whole of the cover- 

 ings of the body are at once cast 

 off, and the insect assumes the 

 form of a pupa or chrysalis ; being 

 wrapt as in a shroud, presenting no 

 appearance of external members, 

 and retaining but feeble indications 

 of life. In this condition it re- 

 mains for a certain period, its 

 internal system continuing in secret 

 the farther consolidation of the 

 organs, until the period arrives 

 when it is qualified to emerge into 

 the world, by bursting asunder the 



