80 CHEMISTEY. 



air. Whenever meat is overcooked in roasting, some of the 

 outside exhibits this separation of carbon by chemical de- 

 composition. 



95. Properties of Charcoal. Although charcoal is so com- 

 bustible, it is in some respects a very unchangeable sub- 

 stance, resisting the action of a great variety of other sub- 

 stances upon it. Hence posts are often charred before be- 

 ing put into the ground. Grain has been found in the ex- 

 cavations of Herculaneum which was charred at the time 

 of the destruction of that city, 1800 years ago, and yet the 

 shape is perfectly preserved, so that you can distinguish 

 between the different kinds of grain. While charcoal is 

 itself so unchangeable, it preserves other substances from 

 change. Hence meat and vegetables are packed in char- 

 coal for long voyages, and the water is kept in casks which 

 are charred on the inside. A ham was kept, by a friend of 

 the author, packed in charcoal-dust eight years, and on be- 

 ing cut was found as fresh and sweet as when first put 

 in. Charcoal is also a great purifier. Tainted meat can 

 be made sweet by being covered with it. Foul and stag- 

 nant water can be deprived of its bad taste by being fil- 

 tered through it. Charcoal is a great decolorizer. Ale 

 and porter filtered through it are deprived of their color, 

 and sugar-refiners decolorize their brown sirups by means 

 of charcoal, and thus make white sugar. Animal charcoal, 

 or bone-black, is the best for such purposes, although only 

 one tenth of it is really charcoal, the other nine tenths be- 

 ing the mineral portion of bone. Other substances besides 

 those which give color are often extracted by charcoal. 

 Thus brandy is rendered pleasanter in taste and smell by 

 being filtered through charcoal, because an acrid volatile 

 oil, called fusel-oil, is extracted. So charcoal takes away 

 from beer not only its color, but that which causes its bitter 

 taste. 



