CARBON. 187 



457. LAMP BLACK. Lamp black, still an- 

 other form of carbon, is made by conducting 

 the smoke of rosiri into chambers, construct- 

 ed for the purpose. It consists of unburned particles of 

 carbon. It is used, extensively, in making paint. 

 Bone black is made by heating bones in closed vessels. 

 It is a sort of charcoal produced from the gelatine of 

 the bones. 



458. PURIFYING PROPERTIES OF CHAR- 



Dcscribe the 



purifying COAL. Charcoal absorbs gases, and retains 



Ztoal S f them iri its P ores ' in lar e qualities. 

 Tainted meat, and musty grain, intimately 

 mixed with it, become sweet. The charcoal has re- 

 moved the unpleasant gases, proceeding from them. 

 The absorbent power of charcoal may be illustrated, 

 by holding a paper moistened with ammonia, in a vial, 

 until the air within it has acquired a strong ammo- 

 niacal odor. On afterward introducing some pow- 

 dered charcoal, and shaking the vial, the odor will be 



removed. 



459. PRESERVATIVE PROPERTIES OF 



Illustrate the , , 



preservative CHARCOAL. Charcoal may be used as a 

 properties of preventive, as well as a corrective of de- 



charcoal f 



cay. Posts, if charred at the bottom, be- 

 fore they are set, are rendered more durable. Water 

 will keep longer in charred vessels than in those which 

 have not thus been prepared. The decay of meats and 

 vegetables is retarded by packing them in charcoal. 

 Charcoal is itself, one of the most unchangeable of sub- 

 stances. Wheat and rye charred at Herculaneum 1800 

 years ago, still retain their perfect shape. 



