44 2 Inquiries relative to the Structure of Wood. 



taneous phenomena, we might hope to make some dis- 

 covery which may assist us a little to elucidate the pro- 

 found obscurity that at present conceals this part of the 

 vegetable economy. 



The specific gravity of the solid parts of a plant being 

 known, it becomes very easy to determine in every case 

 the quantity of air contained in its vessels and pores. 



The following example will render this position per- 

 fectly clear. 



An oak in complete health, in a growing state, was 

 cut down on the 6th of September, 1812. A cylindrical 

 piece, 6 inches long and rather more than an inch in 

 diameter, taken from the middle of the trunk of this 

 young tree, 3 feet above the earth, weighed, when full 

 of sap, 181.57 grammes. 



Upon plunging this piece of wood into a cylindrical 

 vessel about I J inch in diameter and 6\ inches in height, 

 filled with water at the temperature of 62 F., it displaced 

 188.57 grammes of the water;* whence I conclude 

 with certainty, that this piece of oak, filled with sap, 

 possessed a bulk equal to 9.5093 cubic inches, that its 



* In order to determine and keep an account of the quantity of water remaining on 

 the surface of this piece of wood at the instant of withdrawing it from the vessel, it 

 was weighed when taken out, whilst still quite wet. As its weight had been taken 

 previously to the operation, the augmentation it had acquired from the water was ascer- 

 tained to a nicety. 



The vessel when empty weighed 188.22 grammes, and when filled with water at 

 the temperature of 60 F., 474.9 grammes ; so that it contained 286.68 grammes of 

 water. When the piece of wood was plunged into the water, a small glass plate, 

 about two inches in diameter and two lines in thickness, ground with emery to fit it 

 to the edges of the vessel, so as to close it hermetically, was laid upon its mouth, to 

 shut up the piece of wood with the water still remaining in the vessel, whilst its out- 

 side was wiped with a dry cloth. 



When the exterior of the vessel had been thoroughly dried, the glass cover was 

 carefully removed, and the piece of wood withdrawn ; the vessel was then weighed 

 again with its remaining contents of water ; and from its weight the quantity of water 

 displaced by the wood was calculated. 



