IT i- necessary to dearly distinguish between the two closclv-allied 

 Term-. charcoal ;nid carbon. Charcoal is well known to e\ erybodv, 

 although it is no easy matter to obtain it in a chemically pure state. 

 Pure charcoal i- a simple, insoluble, infu-ible. combustible substance 

 produced by heating organic matter, and lias the familiar aspect of a 

 Mark mass, devoid of any crystalline structure, and completely in- 

 - diible. Charcoal is a sub-tance possessing a certain combination of 

 ]>hv.sical and chemical propert ies. This suh>tance. \\-hilst in a state of 

 ignition, combines directly \\itli oxygen: in organic substances it is 

 found in combination \vjtli hydrogen, <i.\\'j4'eii, ';it ro^'en. and sulphur. 

 Hut in all these combination- there is IH> real charcoal, as in the same 

 sense there is no ice in steam. AVliat is found in such combinations is 

 termed 'carbon - that is, an element common 10 charcoal, to t)io>e sub- 

 Mances \\liidi can be formed b\- it. and also to tho-e substances from 

 v.hicli it can be obtained. Carbon mav take the toriu of charcoal, 

 but appeal's also a- diamond and as graphite. It is true that no 

 other element has siidi a limitation in its terminolou'V. '*. \ygen was 

 alwavs called 'o\\'^en, \\hether it \vas in a f ree gase()iis state, or oxygen 

 in the tor m ot o/i >i ie. or o\ \'^en in \\ a t er. ( >r in nit ric acid or in carbonic 

 anhvdride. llut here there is a certain confu-nn. In water it is 

 evident thai there is no oxvgen in ;. ga.-eous form, such as can be 

 obtained in a free -tale, no oxvgen in the form of o/one, but a sub 

 stance \\hidi i- capable of producing both oxygen, o/one. and \valer. 

 As an element oxvLren possesses a kno\\n chemical indi\ iduality, and 

 ;ni influence on the properties < >\ tho-e combinations into which it 

 enters. llvdroifen gas is a substance which read- with dillicultv. but 

 h \ 'dro'_fi ! i as an elemeni represents in its combinations an easily dis- 

 placeable component jiart. ('arbon may be considered as an atom of 

 carbon matter, and charcnal as a collection of -uch atoms forming u 

 whole substance, as molecules in the mass of the substance. The 

 accepted atomic Weight of carbon i- I 1', because that is the least 



