ON WOOD AND CHARCOAL. ]Q3 



shavings, 1 made another experiment, the result of whjch 



was more striking and more satisfactory. 



Having enclosed in a cloth a quantity of powdered Charcoal in 



charcoal, that had been passed through a sieve, I beat it X ery fine poV ' 

 • i • • ,1 i • « er employed, 



strongly in a place where the air was still ; and when the air 



appeared to be well loaded with the fine dust of the charcoal, 



I placed on the ground a white china saucer, quitted the 



place, and left the dust to settle. 



The saucer was covered with it,"* so as to appear of a very 

 dark gray. 



Before all the dust had settled, 1 wrote some letters on the 

 saucer with the point of my finger, and these letters were 

 afterward covered with a still finer dust. 



I imagined it possible, that the part covered by a very fine 

 dust might be found whitened, while that covered with a 

 stratum of coarser charcoal powder would be found perhaps 

 still black. 



The result of the experiment showed, that this precaution Thewholedi^ 

 was not necessary. All the charcoal powder disappeared com- appeared in a 



» t • I ii e- i i • l° w heat, 



pletely in the stove, and the saucer came out perfectly white. 



Another saucer, which had been blackened a little by rub- at which lamp- 

 bing it with lampblack, and placed in the stove by the side black did nGti 

 of that blackened with charcoal dust, came out of the stove 

 as black as it went in. As soon as I saw, that the linden 

 shavings converted into charcoal might be dissipated by the 

 moderate heat of the stove, I suspected, that they had been 

 consumed slowly by a silent and invisible combustion ; and 

 that the product of this combustion could be nothing but 

 carbonic acid gas. 



To clear up this point I made the following experiment. 



Having procured a stock of very dry birch shavings, in Experiment to 

 ribands about a twentieth of a line thick, near half an inch ^ rta j" ^ 

 broad, and six inches long, I dried them for eight days in a converted into 

 room heated by a stove, where the temperature was about carbomc aci< * 

 60° F.; the shavings being laid on a table, at a distance from 

 the stove. Of these shavings thus dried, I took 10 gr., which 

 I placed on a china plate, and heated in the stove, in the 

 manner already described, for 24 hours. When taken out 

 of the stove, they weighed but 7*7gr., and had acquired a 

 deep brown colour inclining to purple. They were still wood 



however, 



