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Carbon. An undecomposed inflammable substance, one of" the 

 simple elementary bodies. Charcoal is almost entirely com- 

 posed of it. Etym., carbo, coal. 



Carbonate of Lime. Lime combines with great avidity with car- 

 bonic acid, a gaseous acid only obtained fluid when united 

 with water, — and all combinations of it with other substances 

 are called Carbonates. All limestones are carbonates of lime, 

 and quick lime is obtained by driving off the carbonic acid by 

 heat. 



Carbonic Acid Gas. A natural gas which often issues from the 

 ground, especially in volcanic countries. Etym., carbo, coal, 

 because the gas is obtained by the slow burning of charcoal. 



Carboniferous. A term usually applied, in a technical sense, to an 

 ancient group of secondary strata, but. any bed containing coal 

 may be said to be carboniferous. Etym., carbo, coal, and/era, 

 to bear. 



Cephalopoda. A class of molluscous animals, having their organs 

 of motion arranged round their head. Etym., xapaXij, cephale, a 

 head, and tto&x, poda, feet. 



Cetacea. An order of vertebratcd mammiferous animals inhabiting 

 the sea. The whale, dolphin, and narwal, are examples. 

 Etym., cete, whale. 



Chalk. A white earthy limestone, the uppermost of the secondary 

 series of strata. 



Chert. A silicious mineral, nearly allied to calccdony and flint, 

 but less homogeneous and simple in texture. A gradual pas- 

 sage from chert to limestone is not uncommon. 



Chloritic Sand. Sand coloured green by an admixture of the simple 

 mineral chlorite. Etym., x^-wpos, chloros, green. 



Clinkstone, called also phonolite, a felspathic rock of the Trap 

 family, usually fissile. It is sonorous when struck with a 

 hammer, whence its name. 



Coal Formation. This term is generally understood to mean the 

 same as the Coal Measures. There are, however, " coal for- 

 mations" in all the geological periods, wherever any of the 

 varieties of coal form a principal constituent part of a group of 

 strata. 



Conformable. When the planes of one set of strata are generally 



