STRUCTURE OF WOOD, &C. 3%7 



We hence conclude, that a cubic inch of this wood, in its Sap, &c. ia 



original state, while the tree was still alive, contained 7*1531 different kind* 



ot wood, 

 grammes of ligneous parts, which formed the fabric of the 



wood, and 4'33f3o, grammes of sap, differing in its specific gra- 

 vity, little or nothing from common water. 



As one cubic inch of the solid parts of this kind of wood 

 weighs 29*45 grammes*, the 7*1531 grammes of ligneous parts 

 found in a cubic inch of the trunk of the living tree, in Sep- 

 tember, could only have occupied the space of 



0*24289 cubic inch. 

 And the 4*3369 grammes of sap, contained 



in it, only 0*21 890 



Consequently, in one cubic inch of this 



wood, there was a bulk of air equal to. . O 53831 



Total, . . . . ? 1*00000 cubic inch. 



The difference between the structure of the oak and of the 

 poplar, becomes very conspicuous on making a comparison, 

 according to the subjoined method, between the constituent 

 parts of these two kinds of wood, both in a growing state. 

 Thus, a cubic inch of wood is composed of, 



Ligneous parts. Sap. Air. 



The oak 039353 0*36122 024525 



The poplar 024289 0*21880 0-53831 



This striking difference, in the proportions of the ligneous 

 substance of sap and of air, discovered in these two species, 

 sufficiently explain the difference observable in their weight 

 and hardness. This inquiry may probably lead to other dis- 

 coveries of more general utility in the study of the vegetable 

 economy. 



Section III. 



Of the relative quantities of Sap and Air found in the same 

 Tree, in [Pinter and in Summer ; and in different portions of 

 the same Tree, at the same time. 



The following experiments were undertaken with a view to 



* See the table, page 323. 



discover 



