M E H 



[287] 



M E 8 



condensed into the fluid metal, by 

 being received into cold vessels. 



Mercury has less affinity for 

 oxygen than most other metals ; it 

 may be distilled over five hundred 

 times, without loss of quantity. 

 It combines, however, with oxygen 

 in two proportions, forming a red 

 and a black oxide. By merely 

 heating these in a retort the oxygen 

 may be driven off, and the metal 

 once more obtained in its pure state. 



The existence of mercury, even 

 in small quantities, in any of its 

 ores, may be ascertained by ming- 

 ling the ore with iron filings, and 

 heating this mixture to redness 

 under any cold body, as a plate of 

 polished copper ; the mercury is 

 volatilized, and condensed in mi- 

 nute globules on the plate. In 

 consequence of the volatility of 

 mercury, it is usually purified by 

 distillation. 



Two of the combinations of mer- 

 cury with chlorine form most 

 valuable and important medicines ; 

 the one called chloride of mercury, 

 or calomel, the other bichloride of 

 mercury, or corrosive sublimate. 

 From the fluid state in which 

 mercury exists, it readily combines 

 with most of the metals, to which, 

 if in sufficient quantity, it imparts 

 a degree of fusibility or softness : 

 these compounds are termed amal- 

 gams. An amalgam of mercury 

 and tin is employed for silvering 

 the backs of looking glasses, and 

 an amalgam of four parts of mer- 

 cury, two of bismuth, one of lead, 

 and one of tin, is used for silvering 

 the inside of glass globes, the 

 amalgam fusing on the globe being 

 placed in hot water. The ready 

 combination of mercury with gold 

 or silver, and the facility with 

 which it may be again separated 

 from them by heat, renders it of 

 great value in the obtaining those 

 metals from their ores and alloys 

 in the operations of mining. 



Mercury is also most useful in 

 the construction of barometers and 

 thermometers. It was known in 

 the remotest ages, and seems to 

 have been employed by the an- 

 cients in gilding, and in separating 

 gold from other bodies, as in the 

 present day. It possesses neither 

 taste nor smell. Native mercury 

 occurs in small globules, dissemina- 

 ted in other metals. These glo- 

 bules are but feebly united to their 

 gangue, and may be liberated by 

 striking or heating the substance 

 which embraces them. It is from 

 the sulphuret of mercury that the 

 metal is principally obtained. 

 Sulphuret of mercury occurs in 

 beds, or large irregular masses, and 

 sometimes in veins. The mines 

 which furnish 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, how- 

 ever, are at Idria; these are situ- 

 ated partly in gray compact lime- 

 stone, and partly in shale. The 

 working these mines is exceedingly 

 injurious to the health and life of 

 those employed. Criminals, and 

 those convicted of political offences, 

 are sent hither to eke out a miser- 

 able existence. They soon lose 

 their teeth, and are subject to 

 paralysis, convulsions, and prema- 

 ture old age. It is said that the 

 surrounding district is so affected 

 by the noxious vapours, that cattle 

 cannot be reared there, and that 

 fruit and grain do not come to 

 maturity. 



MERE. A deep pool of fresh water. 



ME'BOE. In malacology, the name 

 given by Schumacher to certain 

 co wry- shells. 



MERSTHAM BEDS. See Firestone. 



ME'SENTERY. (pecrevrepiov, Gr. from 

 fieffos, middle, and zvvepov, bowel.) 

 A fatty membrane formed of folds 



