CARBON. ^^ 



CARBON. 



This is a very abundant product of nature, being a constituent of 

 all oro-anic bodies;- its purest form is the diamond, a native crystal of 

 carbon ; which is proved to be pure carbon by burning it m oxygen gas, 

 the sole product being carbonic acid. The next purest native variety 

 is o-raphite or plumbago, which also contains some iron ; next to this 

 comes anthracite coal. It is the essential ingredient of common 

 charcoal, which is prepared by burning wood in close vessels. 

 Coke is the charcoal of bituminous coal ; lampblack, that oi resin ; 

 ivory black or animal charcoal is prepared from bones. 



Prop.— C^vhon, as it exists in the diamond, is the hardest sub- 

 stance in nature; it crystallizes in the form of the octohedron or cube ; 

 sp. gr. 3-52 ; is very unchangeable ; bears an intense heat in close 

 vessels without fusing; is not acted on either by acids or alkalies. 

 As obtained from wood, it is hard and brittle ; its apparent lightness 

 is due to its porosity ; a bad conductor of heat ; a good conductor of 

 electricity; is very combustible,— when burnt in the air or in oxygen, 

 givincr rise to carbonic acid ; has the property of absorbing a large 

 quantity of gases or vapours into its pores, though in very different 

 proportions : thus, of ammonia, 90 limes its volume is absorbed, 

 while of hydrogen, it takes up less than twice its own bulk. 



Another very useful property of charcoal, is its power of absorb- 

 incT the colouring matters from organic solutions ; animal charcoal 

 is\est for this purpose. Charcoal is also highly antiseptic; it is 

 hence used for purifving water, in filtering machines ; also to re- 

 move the odour from tainted flesh.— Eq.=6-12. It forms two direct 

 compounds with the oxygen, namely, carbonic oxide and carbonic 



acid. . , • -J 



Carbonic oxide gas, CO.— Prepared by passing carbonic acid gas 

 over red hot charcoal or iron, one half of its oxygen being removed 

 and it becoming converted into carbonic oxide ; or preferably by the 

 action of sulphuric acid on oxalic acid, (an organic acid consisting of 

 equal measures of carbonic acid and carbonic oxide,) which is imme- 

 diately resolved into its constituents ; and on passing the gases through 

 a strong solution of potassa, the carbonic acid is absorbed, and the 

 carbonic oxide may be collected. 



p^o;;._Colourless and inodorous ; sp. gr. 0-9927 ; sparingly ab- 

 sorbed by water ; is neither acid nor alkaline ; a non-supporter of 

 combustion, but combustible, burning with a lambent blue flame, 

 (riving rise to carbonic acid ; it is irrespirable. Mixed with oxygen, 

 ft may be exploded bv the electric spark, forming carbonic acid. 



Carbonic acid, CO^.— Discovered by Dr. Black in 1757, and 

 named by him fixed air ; prepared by the action of sulphuric or 

 muriatic acid on any carbonate ; the gas comes ofl^ with effervescence. 



Prop. — Colourless ; of a pungent odour and taste ; very irrespi- 



