FUEL. 117 



spects, a very unchangeable substance, resisting the action 

 of a great variety of other substances upon it. Hence posts 

 are often charred before being put into the ground. Grain 

 has been found in the excavations at Herculaneum, which 

 was charred at the time of the destruction of that city, 

 eighteen .hundred 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 charcoal for long voyages, 

 and the water is kept in casks which are charred on the 

 inside. Tainted meat can be made sweet by being covered 

 with it. Foul and stagnant water can be deprived of its 

 bad taste by being filtered through it. Charcoal is a great 

 decolorizer. Ale and porter filtered through it are deprived 

 of their color, and sugar-refiners decolorize their brown 

 syrups by means of charcoal, and thus make white sugar. 

 Animal charcoal, or bone-black, is the best for such pur- 

 poses, although only one-tenth of it is really charcoal, the 

 other nine-tenths being the mineral portion of the bone. 



Charcoal will absorb, of some gases, from eighty to ninety 

 times its own bulk. As every point of its surface is a 

 point of attraction, it is supposed to account for the enor- 

 mous accumulation of gases in the spaces of the charcoal. 

 But this accounts for it only in part. There must be some 

 peculiar power in the charcoal to change, in some way, 

 the condition of a gas of which it absorbs ninety times its 

 own bulk. Hooker. 



