STRUCTURE OF WOOD, &C. 321 



of Fahrenheit's scale, (= 200° French) I determined on using 

 shavings of this description in my experiments. 



Section!. 



Of the specific Gravity of the solid Parts of Wood, 



I began with the wood of the lime-tree, of which the tex- Specific gra* 



ture is very fine and regular. From a small board, five inches v,,v ot f ,le 

 i i . ,r . , . . , , t • - parts ot wood, 



Jong and half an inch thick, very dry, I took a quantity of & c . 



thin shavings with a very sharp plane. These were exposed 



for eight days in the month of January, upon a table in a large 



room, not otherwise occupied, in order that they might attract 



from the atmosphere all that moisture which, as an hygrometric 



body, they were capable of imbibing. The temperature of 



the room was about 46 F. 



Ten grammes (154'5 grs.) of those shavings, laid on a China 

 plate, were placed in a large stove made of sheet-Lon, and 

 there exposed to a regular heat of about 245° F. for two hours, 

 in the course of which time they were frequently taken out 

 and weighed, in order to observe the progress ot their drssica- 

 tion. When they ceased to lose weight, the operation was 

 stopped j when perfectly dried, their weight was 8*121 

 grammes. 



By previous trials with my apparatus, I had learned, that if 

 the stove was too much heated, the shavings became disco- 

 loured, which is always indicated by the emission of a particu- 

 lar odour, very readily to be perceived ; but, by a careful regu- 

 lation of the fire, this accident may be avoided, and the shav- 

 ings be thoroughly dried without injury, or even subjecting 

 them to any sensible alteration. 



I concluded that they had not undergone any change, be- 

 cause, upon again exposing them to the atmosphere, they re- 

 gained the same weight which they had, under similar circum- 

 stances, prior to their being dried in the stove. 



Being thus possessed of the weight of my shaving?, as well 

 under exposure to the air as in a dried state, which 1 uter I 

 could not but look upon as being perfect, it only remained to 

 ascertain their weight in water when all their vessels at^d pores 

 were completely filled with that liquid, to enable me to deter- 

 mine 



