366 Account of some new Experiments 



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 pre- 

 caution was not necessary. All the charcoal powder 

 disappeared completely in the stove, and the saucer 

 came out perfectly white. 



Another saucer, which had been blackened a little by 

 rubbing it with lampblack, and placed in the stove by 

 the side 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 sus- 

 pected 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 experi- 

 ment. 



Having procured a stock of very dry birch shavings 

 in ribands about a twentieth of a line thick, near half 

 an inch broad, and six inches long, I dried them for 

 eight days in a room heated by a stove, where the tem- 

 perature was about 60 F., the shavings being laid on a 

 table at a distance from the stove. Of these shavings 

 thus dried, I took 10 grammes, which I placed on a 

 china plate, and heated in the stove, in the manner 

 already described, for twenty-four hours. When taken 

 out of the stove, they weighed but 7.7 grammes, and 

 had acquired a deep brown colour inclining to purple. 

 They were still wood, however ; for, though deeply 

 browned, they burned with a very fine flame. 



Of these brown shavings I made three parcels, each 



