CARBON. 



CARBONIC ACID. 



Caraway delights in a deep, rich, moist 

 loam. The ground for this, as well as other 

 deep-rooting plants, is advantageously dug 

 two spades deep. An open situation is most 

 suitable to it; but in extensive orchards, 

 where the trees are far apart, it may be grown 

 with success. It is propagated by seed, which 

 may be sown in March or April, either broad- 

 cast and raked in, or in drills six inches apart ; 

 in either case being performed thin, and buried 

 about half an inch deep. When well distin-* 

 guishable, the plants must be thinned to six 

 inches apart, and carefully hoed. The hoeing 

 must be several times repeated in the early 

 stages of their growth, to extirpate the weeds, 

 which at a later period cannot be conveniently 

 got at. The plants flower in June, and ripen 

 their seed at the close of summer. (G. W. 

 Johnson's Kitch. Card. English Flora, vol. ii. 

 p. 86 ; M'Culloch's Com. Diet. ; Willich't Dom. 

 Eneyc. ; Brande's Diet. Science.) 



CARBON (Fr. carbone ; Lat. carlo). A 

 hitherto undecompounded combustible body, 

 which enters into the composition, in some 

 form or other, of all vegetable substances. In 

 a perfectly pure state, carbon constitutes dia- 

 mond. Carbonaceous substances are usually 

 more or less compounded, containing hydrogen, 

 or sometimes oxygen, and azote, along with 

 earthy and metallic matters. Carbon, tolerably 

 pure, abounds in the mineral kingdom ; and, 

 in a combined state, it forms a main consti- 

 tuent of vegetable and animal bodies. Anthra- 

 cite is a mineral charcoal, differing from 

 common pit-coal in containing no bitumen, 

 and therefore burning without flame or smoke. 

 Coke is the carbonaceous mass which remains 

 after pit-coal has been exposed to ignition for 

 some time out of contact of air; its volatile 

 parts having been dissipated by the heat. It 

 is a spongy substance, of an iron-black colour, 

 a somewhat metallic lustre, and does not easily 

 burn unless several pieces are kindled toge- 

 ther. With a good draught, however, it pro- 

 duces a most intense heat. It is readily 

 obtained in the form of charcoal by heating 

 wood (and any kind of wood will answer the 

 purpose) red-hot, covered with sand, in a cru- 

 cible. The covering with sand is added to 

 prevent the wood undergoing combustion by 

 coming in contact with the atmosphere. In 

 this state when reduced to powder, charcoal 

 constitutes an excellent manure for most soils, 

 either when applied by itself, or mixed with 

 decomposing animal and vegetable substances. 

 In such cases it absorbs a considerable volume 

 of the gases which such substances constantly 

 emit. Thus, reckoning the bulk of the char- 

 coal to be 1, it absorbs of 



Volnmei. 

 Ammoniacal gas ------ 90 



Sulphuretted hydrogen ... _ 55 

 Carbonic acid gaa .... 35 



When burnt, charcoal unites with the oxygen 

 of the atmosphere, and forms, in the state of 

 carbonic acid gas, a very important portion 

 of the gases required by all plants for their 

 healthy vegetation. (See GASES, THEIR USE 

 TO VEGETATIOX.) Carbon constitutes about 

 42-47 per cent, in sugar, 41-906 per cent, in 

 gum, 43-55 per cent, in wheat starch, 52-58 per 

 cent, in the wood of the oak, and 51-45 in that 



of the beech ; 46-83 in pure acetic acid or vine- 

 gar, 36-167 in tartaric acid, and 41-369 in the 

 citric. In the state of carbonic acid gas, and 

 in various organic matters, it is found in all 

 cultivated soils, in all waters, and in the atmo- 

 sphere ; and in each situation, as will be more 

 particularly described under the head GASES, 

 it is absorbed by and becomes the food of 

 plants. 



CARBONATES. A peculiar class of salts 

 formed by the combination of carbonic acid 

 gas with various earths, alkalies, and metallic 

 oxides. The composition of those most com- 

 monly met with by the farmer is as follows : 



Acid. Base. 



Carbonate of lime, chalk, lime- 

 stone, &c. - 66-2 33-8 

 Carbonate of magnesia - - 68-75 31-25 

 Bicarbonate of potash ... 46-19 53'8l 

 Carbonate of soila ... 40-14 59 86 

 Carbonate of ammonia - - 56-41 4359 



CARBONIC ACID GAS. A peculiar gas, 

 the same as that emitted by fermenting beer, 

 or other liquors ; it is inhaled by, and its car- 

 bon is the food of plants. It is composed of 

 carbon 72-73, oxygen 27-27. See GASES, THEIR 

 USK TO VEGETATION, 



It is important to know, that carbonic acid 

 gas is poisonous, if breathed. If, for example, 

 a person descends into a tun where fermented 

 liquor occupies the bottom, and an atmosphere 

 of carbonic acid gas floating over it ; as soon 

 as his mouth is immersed in it, he is suffo- 

 cated in the same manner as if his mouth and 

 nostrils were closed. He dies from the defect 

 of atmospheric air in the lungs, and the circu- 

 lation of black blood through the brain. This 

 is the manner also in which death occurs 

 when persons descend into old wells and cel- 

 lars that have been long closed. When the 

 gas is diluted with air, as for instance, when a 

 person dies by burning charcoal in a chafing- 

 dish in a bed-room, he is not suffocated ; but 

 he dies from the sedative influence of the di- 

 luted carbonic acid, which is breathed, on the 

 nervous system. When such accidents hap- 

 pen, persons should not venture to bring out 

 the bodies, until a quantity of pure lime mixed 

 with water to the thickness of milk, has been 

 thrown into the tun, well, or cellar ; or in the 

 event of death from burning charcoal, until a 

 current of air has been sent through the apart- 

 ment. The bodies should be laid on their 

 backs, with the heads moderately elevated; 

 cold water dashed on the chest, and frictions 

 employed over the whole body ; and the aid of 

 a medical practitioner quickly procured. 



This is the heaviest of all gases, its 

 weight, compared with the common air of 

 the atmosphere, being about one-half greater. 

 This is the reason why it always subsides 

 to the bottom of apartments, wells, sinks, &c., 

 where it may have been formed, or gained 

 access. Its weight even admits of its being 

 poured from one vessel to another. Hence 

 it was at first called aerial add. From its 

 existing copiously, in a solid state, in lime- 

 stones and the mild alkalis, it was styled 

 fixed air by its proper discoverer, Dr. Black. 

 About one volume of it exists in one thou- 

 sand volumes of common atmospheric air, 

 which may be made manifest by the crust '~f 



263 



