WOOD. 



89 



From these analyses it appears that wood in the natural state 

 contains more carbon than woody tissue obtained in the way of puri- 

 fication, and that this latter substance is also richer in carbon than 

 the cellular tissue which necessarily forms part of it. In the 

 purified woody tissue, therefore, the cellular tissue is associated with 

 the principle which fills its cells, or which incrusts it, and it is 

 to this matter that M. Payen has applied the name of incrusting 

 matter ; it is wood properly so called ; it is that which gives to 

 wood its hardness, its tenacity ; it predominates in hard wood and in 

 knots ; it corresponds with the duramen of physiologists ; it consti- 

 tutes almost the whole of the hard particles which are met with in 

 woody pears and in cork, and which are hard enough to blunt well- 

 tempered steel instruments. As this incrusting matter is friable, in 

 many instances it may be pulverized and separated from the tissue 

 which surrounds it, this last tearing or yielding in shreds under the 

 pestle. By means of the sieve the incrusting matter may in this 

 simple way be obtained nearly in a state of purity. The analysis 

 of M. Payen shows it to consist of : — 



Carbon 53-8 



Hydrogen 6.0 



Oxygen 40-2 



100.0 



Deducting resinous matters susceptible of solution in alcohol or 

 ether, and of gummy and other substances which are soluble in water, 

 the tissues of vegetables must consequently possess an elementary 

 composition which varies between that of the cellular tissue and 

 that of the incrusting matter ; these are the extreme terms, and the 

 entire composition of the mixed tissues will be by so much the richer 

 in carbon as they contain less cellular tissue. The incrusting mat- 

 ter being soluble in alkaline leys, it was by treating wood with solu- 

 tions of soda and potash that M. Payen succeeded in obtaining the 

 cellular tissue, which is much less susceptible of the action of these 



8* 



