obtained in the distillation of Woody Is'c, 25 



It was also exceedingly difficult to burn, requiring a long con- 

 tinued red heat, after which it left an oxide or rather a carbonat-of 

 iron, such as remains from the combustion of plumbago. It is in 

 fact to be considered as an artificial plumbago, a substance of whose 

 nature all the charcoals of difficult combustibility partake, deriving 

 their resemblance apparently from the same cause. 



The formation of this plumbaginous substance serves to shew a 

 very powerful affinity between iron and carbon, even where the 

 proportions are very different from those which enter into the com- 

 position of steel. But to effect this combination, it is necessary 

 that the carbon be in a state of previous union with other substances, 

 and that it be applied to the iron In that state. It will be in vain 

 that we attempt to combine iron with charcoal for this end, unless 

 the charcoal or carbon be in that state of very minute division In 

 which it exists when precipitated by a new affinity from some pre- 

 vious combination. 



It is necessary now to account for the iron in this compound. 



This distillation of wood for charcoal Is carried on in iron vessels, 

 and hence is derived the iron which enters into the composition of 

 the pitch. I will not say that it Is solely derived thence, as It is 

 probable that if there were iron contained in the vegetable matter, 

 it would also be found in the same place. When the acetic acid 

 has been separated the iron remains united to the pitch. This fact 

 may shew us, that If in the destructive analysis of vegetable (and 

 probably animal) matter, we trust to find the Iron they may con- 

 tain in the residual matter of the distillation, we may be disappointed, 

 since It may be carried over, together with the substances I have now 

 been describing, in the act of ebullition, as happens in this very 

 case, its tendency being to copiblne with them, in preference to the 

 charcoal. 



Vol. II. D 



