CARBON. 301 



destroys it, and has a considerable effect in retarding the pu- 

 trefaction of organic matter with which it is placed in contact. 

 Water is also found to remain sweet, and wine to be improved 

 in quality if kept in casks of which the inside has been charred. 

 In the state of a coarse powder wood charcoal is particularly 

 applicable as a filter for spirits, which it deprives of the essen- 

 tial oil which they contain. It is much less destructible by 

 atmospheric agencies than wood, and hence the points of stakes 

 are often charred, before being driven into the ground, in order 

 to preserve them. 



4. The coke of those species of coal, which do not fuse 

 when heated, is a remarkably dense charcoal, considerably re- 

 sembling that of wood, and of great value as fuel from the 

 high temperature which can be produced by its combustion. 

 When burned it generally leaves 2 or 3 per cent of earthy 

 ashes, while the ashes from wood charcoal seldom exceed 1 per 

 cent. 



5. Ivory black, bone-charcoal and animal charcoal are names 

 applied to bones calcined or converted into charcoal in a close 

 vessel. The charcoal thus produced is mixed with not less 

 than 10 times its weight of phosphate of lime, and being in a 

 state of extreme division, exposes a great deal of surface. It 

 possesses a remarkable attraction for organic colouring matters, 

 and is extensively used in withdrawing the colouring matter 

 from syrup, in the refining of sugar, from the solution of tar- 

 taric acid, and in the purification of many other organic liquors. 

 The usual practice, which was introduced by Dumont, is to 

 filter the liquid to be discoloured, through a bed of this char- 

 coal, in grains of the size of those of gunpowder, and of two or 

 three feet in thickness. It is found that the discolouring power 

 is greatly reduced by dissolving out the phosphate of lime from 

 ivory black by an acid, although this must be done in certain 

 applications of it, as when it is used to discolour the vegetable 

 acids. A charcoal possessed of the same valuable property 

 even in a higher degree for its weight, is produced by calcining 

 dried blood, horns, hoofs, clippings of hides, in contact with 

 carbonate of potash, and washing the calcined mass afterwards 

 with water. Even vegetable matters aiford a charcoal, pos- 

 sessed of considerable discolouring power, if mixed with chalk, 

 calcined flint or any other earthy powder, before being car- 

 bonized. One hundred parts of pipe clay made into a thin 



