322 STRUCTURE OF WOOD, &C. 



Specific gr.i- ;nine the specific gravity of the solid parts of this wood, which 

 pities ot wo jd, was accom pi| s hed without difficulty by the following process: 



A cylinder copper vessel, ten inches in diameter, and as many 

 deep, was filled with water from the Seine, previously well 

 filtered, and being set upon a common chafing dish, was made 

 to boil for some time, to expel the air contained in the water. 

 The shavings were then thrown into the boiling water, and 

 kept in that state for an hour. The water was not long in 

 filling the vessels and pores of the shavings, from which it 

 dislodged the air contained in them ; so that the wood, speci- 

 fically heavier than the water, was precipitated to the bottom 

 of the vessel, and there remained. 



When the vessel was removed from the chafing-dish, the 

 water was suffered to cool to the temperature of 60° F. and 

 then plunging in both hands, I placed (under the water) all 

 the shavings in a cylindric glass vase, whose weight I had previ- 

 ously ascertained, which was suspended in the water by a 

 silken cord, fastened at its other extremity to the arm of an 

 accurate hydrostatic balance. 



On weighing the shavings in the glass vase thus immersed, 

 I found their weight equal to 2*651 grammes. 



As the shavings, while dry, weighed 8*121 grammes, in the 

 air, and 2*651 grammes in the water, they must have lost 5*47 

 grammes of their weight in the latter j consequently, they 

 must have displaced 5*47 grammes of water ; and the specific 

 gravity of the solid parts of this wood must be to that of the 

 water, at the temperature of 6CT F. as 8*121 to 547, or as 

 14*846* to J 0*000. 



It may, perhaps, excite some surprise, that the solid parts of 

 so light a wood as that of the lime-tree should be heavier, by 

 nearly one-half, than water, taken in equal bulks. But this 

 surprise will, without doubt, be increased when I declare, that 

 the specific gravities of the solid parts of all kinds of wood 

 are so nearly alike, as almost to induce a belief, that there is 

 the same identity in the ligneous substance of all sorts of wood, 

 as in the osseous substance of all species of animals. 



I procured, from a joiner's work-shop, dried wood of the 



eight following species, viz. poplar, lime, birch, fir, maple, 



beech, elm, and oak ; and had them cut into small boards, 



five inches in length, and six inches broad, from each of which 



( I 



