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C 



gangue, and may be liberated by striking 

 or heating the substance which embraces 

 them. It is from the sulphuret of mer- 

 cury that the metal is principally ob- 

 tained. Sulphuret of mercury occurs in 

 beds, or large irregular masses, and some- 

 times in veins. The mines which fur- 

 nish the ore, sulphuret of mercury, are 

 by no means common ; Spain, Germany, 

 and Peru possess the most important. 

 In Spain, at Almaden, these mines are in 

 a mountain of argillaceous slate or shale. 

 The most celebrated, however, are at 

 Idria ; these are situated partly in gray 

 compact limestone, and partly in shale. 

 The working these mines is exceedingly 

 injurious to the health and life of those 

 employed. Criminals, and those con- 

 victed of political offences, are sent hither 

 to eke out a miserable existence. They 

 soon lose their teeth, and are subject to 

 paralysis, convulsions, and premature old 

 age. It is said that the surrounding dis- 

 trict is so affected by the noxious vapours, 

 that cattle cannot be reared there, and that 

 fruit and grain do^not come to maturity. 



ME'SENTERY. (ntvivrkpiov, Gr. from 

 /igoroc, middle, and tvrfpov, bowel.) A 

 fatty membrane formed of folds of the 

 peritoneum. This is a fine and delicate 

 membrane which connects the intestines 

 to the spine, and which appears to be 

 interposed in order to allow to the intes- 

 tines that freedom of motion which is so 

 necessary to the proper performance of 

 their functions. 



MESENTE'RIC. Pertaining to the mesentery, 

 as the mesenteric glands, &c. 



MESOTHO'RAX. (from /^e<roc, middle, and 

 9d)pa%, chest.) In entomology, the meso- 

 thorax gives origin to the second pair of 

 legs, and also the first pair of wings, or to 

 the elytra, of insects. 



ME'SOTYPE. (from ^sdoc, middle, and 

 rwTroc, form.) Prismatic zeolite ; a simple 

 mineral of the zeolite family, occurring 

 in drusy cavities, or in veins in secondary 

 trap rocks. The Prismatischer Kuphon- 

 spath of Mohs. Mesotype is of a white, 

 red, yellow, or yellowish-brown colour. 

 It occurs regularly crystallized. It con- 

 sists of silica 54'40, alumina 19'75, soda 

 15-05, lime 1*60, water 9*80. Specific 

 gravity 2*3. 



METACA'RPAL. (from /utrd, with, and 

 KapTrbQ, the wrist.) Belonging to the 

 metacarpus; as the metacarpal bones, &c. 



METACA'RPUS. (from fierd, Yfith, and 

 KapTTog, the wrist.) That part of the 

 superior extremity which connects the 

 wrist with the fingers ; what is commonly 

 known as the hand, but not including 

 either the wrist or the fingers. 



METABO'LIANS. (from /isra/SaXXw, Gr. to 

 change.) That sub-class of insects which 



I] MET 



undergo a metamorphosis, and are usually 

 fitted with wings in their final state. The 

 insects of the class Condylopes may be 

 divided into two sub-classes, namely, 

 Ametabolians, or those that do not un- 

 dergo any metamorphosis, and have no 

 wings ; and Metabolians. 

 ME'TAL. (fj,kra\\ov, Gr. metallum, Lat. 

 mttal, Fr. metallo, It. metall, Germ.) 

 Metals, as presented by nature, are some- 

 times pure, or combined with each other 

 only, and are said to exist in a metallic 

 state. But more frequently they are 

 combined with oxygen, sulphur, &c., by 

 which their peculiar metallic properties 

 are more or less disguised ; in this case 

 the metal is said to be mineralized, and 

 the oxygen, or sulphur, is called the mi- 

 neralizer. All the individuals of the class 

 of metals, with the exception perhaps of 

 iron, are perfectly inert and harmless ; 

 even arsenic, lead, copper, and mercury, 

 which in certain states of combination 

 constitute some of the most virulent of 

 known substances, exert no action upon 

 the living system, unless they be in union 

 with some other body ; but when so 

 united, how valuable do they become, and 

 what various medicinal effects may they 

 not be made to produce ! The metals at 

 present known are forty-three in number. 

 Of these, seven were known in the earliest 

 ages, and, in consequence of a supersti- 

 tious belief in the influence of the stars 

 over human affairs, were first distinguished 

 by the names and signs of the planets ; 

 and as the latter were supposed to hold 

 dominion over time, so were astrologers 

 led to believe that some, more than others, 

 had an influence on certain days of the 

 week ; and, moreover, that they could 

 impart to the corresponding metals con- 

 siderable efficacy upon the particular days 

 which were devoted to them. As regards 

 the ages of metals, tin, molybdena, tung- 

 sten, and wolfram, are ranked as the most 

 ancient ; uranium and bismuth succeed. 

 Gold and copper are deemed relatively 

 and comparatively as new metals. Iron 

 is of all ages. The specific gravity of 

 metals, if we exclude those recently dis- 

 covered by Sir H. Davy, is always greater 

 than that of minerals ; tellurium, the 

 lightest metal, being above 6*0, while the 

 heaviest earthy body is less than 5'0. 

 Metals are opaque ; they possess a pecu- 

 liar lustre, which has been termed metallic 

 lustre, retaining it even when reduced to 

 powder. They are mostly malleable, or 

 capable of being hammered into various 

 orders and thin leaves ; and ductile, or 

 capable of being drawn into wires of 

 greater or less fineness. They are not 

 soluble in water. They all unite with 

 oxygen, and, probably, all with chlorine. 



