CARBON, a non-metallic elementary solid body, which is widely diffused throughout nature. The purest and at the same time the rarest form in which it occurs is that of the diamond ; the more common states in which it is met with are those of anthracite, graphite, and coal ; but in these cases it is not free from admixture. Another well-known form of carbon, but still impure,is charcoal. Carbon is the chief element in three groups of sub stances :—the mineral forms, such as diamond, anthracite, &c. ; the carbonates ; and the vege table series, as coal, asphaltum, peat, amber, &c.
Charcoal consists mainly of carbon procured from the decomposition of wood by burning. This operation is generally conducted in pits made in the gronnd; sometimes however it is carried on in iron cylinders. Wood is es sentially composed of carbon, oxygen, and hydrogen. By the action of the heat it is de composed the oxygen and hydrogen are ex count both the fruit and seeds of different pelled, and uniting in certain proportions form water ; and also with carbon various gaseous and other compounds are formed. Among the latter are acetic acid, sometimes called pyroligneous acid, and a peculiar inflammable fluid known by the name of pyroxilic spirit, and tar.
Charcoal has the following properties. It is black, lighter than water, and full of pores, occasioned by the expulsion of the bodies volatilised. Charcoal, from whatever source procured, is absolutely infusible by any degree of heat however great; neither that of a mir ror, the oxhydrogen blow pipe, nor the voltaic discharge, being sufficient to produce fusion. In its common state it is one of the worst con ductors of heat known, but its power is in creased after being strongly heated. Charcoal is a conductor of electricity, which is so far from being the case with the diamond, that it may be rendered electrical by friction.
Charcoal is tasteless, inodorous, and inso luble in water. It possesses the property of destroying colouring matter, especially the charcoal procured by burning bones, which is usually called animal charcoal. It is largely used for this purpose in sugar refining. It has the power of condensing gaseous bodies to a greater degree than most or perhaps any other substances. Charcoal is highly com bustible; it burns in the air when strongly heated, though not very rapidly. During this combustion carbonic acid is formed by the union of the oxygen of the air with carbon.
It has been mentioned that charcoal is not pure carbon ; when a quantity is burnt there always remains a portion of ashes containing a considerable quantity of carbonate of potash and some other alkaline and earthy salts, which have been taken up from the soil in which the tree grew that furnished the char coal.
Charcoal is used not merely for combustion, but also for the important purpose of making gunpowder. It is also applied to other various well-known uses. Its power of absorbing gases and moisture renders it useful in some cases, while in other cases it seems to act by some power exerted on the vital energies of the system. Charcoal, especially animal charcoal, possesses the power of destroying the colour, smell, and taste of a great variety of vegetable and animal substances, particularly of muci lages and oils, and of matters in which extrac tive abounds. Meat and game too far decom posed may be restored to a condition fit for use by the employment of finely powdered charcoal, assisted by sulphuric acid. Water also may be restored from a tainted state by filtering it through charcoal. Charcoal, both from its antiseptic and vital properties, is use ful in many forms of disease.