262 Ufe of Charcoal in reducing Metals. [Book VI. 



muriatic, the unknown bafes of whicri have a ftronger 

 attraction for oxygen than it has. 



Charcoal readily decompofes the phofphoric and 

 fulphuric acids, the bafes of which burn at a lower 

 temperature j and this fadt evinces, that the degree of 

 heat at which the combuftion of a body begins does not 

 accurately mark its degree of attraction for oxygen. 



From the ftrong affinity of the carbonaceous prin* 

 ciple for oxygen, charcoal is the moft powerful fub- 

 ftance which can be ufed in the reduction of metals. 

 Charcoal has alfo another advantage over other in- 

 flammable fubflances in thefe operations, which is, that 

 it bears a great degree of heat without volatilization. 



According to the experiments of Lavoifier, in the 

 combuftion of one pound of charcoal, two pounds 

 nine ounces one drachm ten grains of oxygen gas are 

 abforbed, and three pounds nine ounces one drachm 

 ten grains of carbonic acid gas are formed. 



The carbonaceous principle, or carbon, is one of 

 the moft important fubftances in nature. It is one of 

 the neceflary conftituent parts of animal fubftances, and 

 enters into the compofition of all alimentary matters, 

 flour, fugar, mucilage, oil, &c. It is alfo the chief 

 ingredient in all kinds of fuel. 



PLUMBAGO, or black lead, is found to confift of car- 

 bon combined with about one tenth of its weight of 

 iron. It appears to be fcarcely inflammable, but 

 may, however, be almoft entirely confumed with the 

 production of carbonic acid gas, by keeping it heated 

 to a great degree, and agitated fo as to expofe it tho- 

 roughly to the air. It may be alfo deflagrated with a 

 large proportion of nitre in a red heat. It is found in 

 a feparate ftate in a variety of places ; but the fpecies 

 beft adapted for making pencils comes chiefly from 

 Burrowdale, in Cumberland, For this purpofe it 

 6 is 



