M U 



303 



M IT 



rants our writing it mould.) The 

 name given to that superficial ac- 

 cumulation of various substances 

 which lies upon the surface of the 

 dry land, and covers the rocks 

 below. 



"The process," says Dr. Buck- 

 land, " is obvious whereby even 

 solid rocks are converted into soil 

 fit for the maintenance of vegetation, 

 by simple exposure to atmospheric 

 agency; the disintegration produced 

 by the vicissitudes of heat and cold, 

 moisture and dryness, reduces the 

 surface of almost all strata to a 

 comminuted strata of soil, or mould, 

 the fertility of which is usually in 

 proportion to the compound nature 

 of its ingredients." 



MOUNTAIN COEK. (The Berg kork 

 of Werner; Suber montanum of 

 Kirwan ; Asbeste suberiforme of 

 Brongniart.) A white or grey 

 variety of asbestos, to which the 

 name of mountain cork has been 

 given from its extreme lightness; 

 sp. gr. from 0'68 to 0*99, con- 

 sequently so light as to swim in 

 water. Its structure is fibrous; 

 the fibres promiscuous and inter- 

 woven. Its constituents are silex 

 56-2, magnesia 26-1, lime 12'7, 

 iron 3*0, alumine 20. It occurs 

 in Prance and Saxony. 



MOU'NTAIN BLUE. A species of blue 

 malachite or blue copper. The 

 Cuivre carbonate bleu of Haiiy; 

 Kupfer lazur of "Werner. Carbon- 

 ate of copper. The characteristic 

 colour of mountain blue is azure- 

 blue, often exceedingly beautiful 

 and splendent. Occurs regularly 

 crystallized in scopiform and stel- 

 lular concretions, radiated, and also 

 curved lamellar. When rubbed on 

 paper, it leaves a light blue streak. 

 Sp. gr. from 3'20 to 3*60. It dis- 

 solves with effervescence in nitric 

 acid. It is scarcely fusible alone, 

 but with borax, to which it com- 

 municates a fine green, it yields a 

 globule of copper. Its constituents 



are copper 66, carbonic acid 18, 

 oxygen 8, water 2. 

 MOU'NTAIN LI'MESTONE. (The Calcaire 

 carbonifere, Calcaire anthraxifere, 

 and Calcaire de transition of the 

 French ; the Kohlenkalk, and 

 Ueberganskalk of the Germans. 

 Conybeare proposed to designate 

 this rock "Carboniferous Limstone." 

 By some authors it has been termed 

 metalliferous limestone, from its 

 mineral riches; by others, entro- 

 chal or encrinal limestone, from its 

 organic remains : it has also been 

 proposed to designate it by the 

 Wernerian name, "first flcetz for- 

 mation.") A series of marine 

 limestone strata, whose geological 

 position is immediately below the 

 coal measures and above the old red 

 sandstone. To this formation the 

 French have given the name of Cal- 

 caire de transition. Mountain lime- 

 stone is one of the most important 

 calcareous rocks in England and 

 Wales, both from its extent, the 

 thickness and number of its beds, 

 the quantity and variety of its 

 organic remains, and its richness 

 in metallic ores, particularly of 

 lead. ID Derbyshire, where the 

 different beds of limestone have 

 been pierced through by the mi- 

 ners, the average thickness of the 

 three uppermost is about 160 yards; 

 the series is said to exceed, in some 

 instances, 1000 feet: the beds are 

 separated by beds of trap or basalt, 

 resembling ancient lavas. The 

 limestone is generally sufficiently 

 hard to bear a polish, and forms 

 what is denominated marble, of 

 considerable beauty. The moun- 

 tain limestone formation occupies 

 an immense tract in Northumber- 

 land, Durham and Yorkshire, from 

 which country it runs out into a 

 curve to encircle on the north, and 

 partially on the south, the group of 

 Cumbrian slate mountains. It also 

 appears in great force in Derby- 

 shire, ranges through Flint and 



