462 Inquiries relative to the Structure of Wood. 



at a time, and then not so as to admit the obtrusion of 

 any extraneous* matter. 



When one of these vases is put into the stove, it is 

 placed upon a square tile, or half-brick, of burned earth, 

 and another of the same kind is also laid upon the cover 

 to keep it steady. 



During the carbonization of the wood, the interior 

 of the vase is always clouded, assuming a very deep 

 blackish-yellow colour ; and during the operation a 

 strong smell of soot or of pyroligneous acid issues 

 from the stove ; which is even insupportable at the 

 commencement, if it be too nearly approached, as well 

 as on withdrawing the vases from the stove, if the covers 

 be removed without due precaution. 



There is, therefore, a decomposition during the' carbon- 

 ization of wood, and a formation of pyroligneous acid. 

 This fact has been long known ; but, in some of my 

 experiments, and particularly in those made upon fir, with 

 a very moderate fire, I obtained a product, which, upon a 

 very exact scrutiny, appeared to me to be bitumen. 



This product had been condensed upon the glass 

 cover, whence it had afterwards run in large drops upon 

 the vertical surface of the side of the vase. It was hard 

 and brittle, of a dark yellow colour ; it was not affected 

 by boiling water, nor by boiling alcohol, but was grad- 

 ually dissolved by sulphuric ether. 



It would be superfluous here to enter upon the de- 

 tails of all my experiments relative to the carbonization 

 of wood. As the process .1 have employed cannot now 

 but be well known, after what I have said in this memoir 

 and in the one that I had the honour to present to the 

 Class on the joth of December in last year, I shall here 

 only give the result of those experiments. 



