CAR 



[39 ] 



C A II 



be placed in a closed vessel, and kept red- 

 hot for some time, it is converted into a 

 shining black brittle substance, possessing 

 neither smell nor taste, commonly known 

 as charcoal. Charcoal is infusible, insol- 

 uble in water, is capable of combining 

 both with hydrogen and sulphur, is a 

 conductor of electricity, and has a power- 

 ful affinity for oxygen. Carbon is ob- 

 tained nearly pure in charcoal ; but, what 

 is astonishing, the diamond appears to 

 be this elementary substance in its purest 

 known form. Why it is, or how it is, 

 that the same elementary substance can, 

 with little or no addition, form two 

 bodies so dissimilar in every respect as 

 charcoal and diamond, the one a soft, 

 black, brittle mass, the other the clearest 

 and hardest body we know of, is a mys- 

 tery beyond our weak comprehensions to 

 understand. Carbon enters as a con- 

 stituent part into many of the slate rocks, 

 to which it generally communicates a dark 

 colour : it forms also regular beds of con- 

 siderable thickness, being the principal 

 constituent part of coal. Combined with 

 oxygen, carbon forms carbonic acid or 

 fixed air. 



CARBONA'CEOUS. (from carbon.) Con- 

 taining carbon ; pertaining to carbon. 



CA'RBONATE. A combination of carbonic 

 acid with a base. Carbonic acid is capable 

 of combining with earths, oxides, and al- 

 kalies, and to these combinations the term 

 carbonate has been applied ; thus we 

 have the carbonate of lime, carbonate of 

 magnesia, carbonate of lead, carbonate 

 of iron, carbonate of ammonia, &c. &c.&c. 



CA'RBONATED. Combined with carbon. 



CA'RBONATE OF LIME. A union of car- 

 bonic acid and lime, consisting of 57 

 parts of lime and 43 of carbonic acid. 

 Carbonate of lime, under the several 

 names of chalk, lime-stone, marble, &c. 

 is found most abundantly throughout na- 

 ture. All limestones effervesce when a 

 drop of strong acid is thrown on them, 

 and they entirely dissolve in nitric or 

 muriatic acid. 



CARBO'NIC ACID. A compound of carbon 

 and oxygen ; it has been called aerial 

 acid, fixed air, cretaceous acid, and me- 

 phitic gas. Carbonic acid is very plenti- 

 fully disengaged from springs in almost 

 all countries, but especially near active 

 or extinct volcanoes. This elastic fluid 

 has the property of decomposing many of 

 the hardest rocks with which it comes in 

 contact, particularly that numerous class 

 in whose composition felspar is an in- 

 gredient. In volcanic countries these 

 gaseous emanations are not confined to 

 springs, but rise up in the state of pure 

 gas from the soil in various places. The 

 Grotto del Cane, near Naples, affords an 



excellent example. The acid is invisible, 

 is specifically heavier than atmospheric 

 air, and on this account it accumulates 

 in any cavities on the surface of the 

 ground. It may be dipped out of any 

 excavations in which it has accumulated, 

 poured into a bottle, like water, corked, 

 and carried to any distance. It is fatal 

 to human life when breathed undiluted, 

 and by the miners it is called choke- 

 damp. 



CARBONIFEROUS, (from carlo and fero, 

 Lat.) Containing carbon ; yielding car- 

 bon. 



CA'RBONISED. Converted into charcoal, or 

 carbon. 



CARBONIZA'TION. The converting into 

 carbon. 



CA'RBURET. A compound formed by the 

 combination of carbon with any metal, 

 alkali, or earth. 



CA'RBURETTED HYDROGEN GAS. The fire- 

 damp of miners. 



CA'RBUNCLE. (carbuncuhis, Lat.) A 

 precious stone, supposed by some authors 

 to be the ruby, by others the garnet ; 

 called by the Greeks anthrax. 



CA'RDIAC. } (from icapia,the heart, Gr. 



CARDI'ACAL. \ cardiaque, Fr.) Relating 

 to the heart, as the cardiac nerves, &c. 



CARDIA'CEA. In Cuvier's arrangement a 

 family of bivalves of the class Testacea, 

 comprising Cardium, Donax, Cyclades, 

 Corbis, Tellina, Lucina, and Venus. 



CA'RDITA. An inequilateral bivalve, found 

 at various depths to thirteen fathoms, in 

 mud and sands ; sometimes attached to 

 stones. The hinge with two unequal 

 teeth ; the hinge tooth the shortest, be- 

 neath the beak ; the other longitudinal, 

 beneath the insertion of the cartilage. 

 Lamarck places Cardium in the family 

 Cardiacea. 



CA'RDIUM. The cockle ; animal a tethys. 

 A genus of bivalves, the shells of which 

 are characterized by the teeth of their 

 hinge, and by the projection of their 

 beaks ; the latter giving them a cordiform 

 appearance. They are generally orna- 

 mented with longitudinal ridges, and 

 frequently with strise, scales or spines. 

 The different species are found at depths 

 varying to thirteen fathoms, in mud, 

 sands, and gravel. This genus belongs 

 to the class Vermes, order Testacea. 

 Many of the species, as the C. aculea- 

 tum, arcuatum, ciliare, discors, edule, 

 elongatum, Isevigatum, nodosum, spi- 

 nosum, &c. &c. are found on our coasts. 

 The cardium, with the exception of one 

 species, cardium fiuviatile, has only 

 been found to inhabit the ocean ; gene- 

 rally they live just under the surface of 

 the sand. Fifty-two species have been 

 described. 



