102 OK WOOD AND CHARCOAL. 



Heated a To clear up my doubts, I replaced the apparatus in the 



fourth nine. stovCj an( j neate( j j t a g a j n as before for twelve hours, and 



afterward left it in the stove twelve hours to cool. 

 Result*. Q n taking out the apparatus I fonnd, that the shavings 



weighed only 1*5 gr. The jar was less transparent, and 

 of a blackish yellow colour throughout; but particularly in 

 its upper part, above the level of the brim of the saucer, 

 in which the shavings were. These shavings were still Qf a 

 perfect black. 

 Heated a fifth Having heated the apparatus again for twelve hours, 

 and then left it to cool, I was surprised on taking it out 

 of the stove the next day to find, that the jar had again 

 become clear and transparent. Not the least trace of the 

 yellow coating, with which its inner surface had been co- 

 vered, now remained. 

 State of the On examining the wood \ found, that this also had 

 changed its colour. It had assumed a blueish hue, pretty 

 deep, but very different from the decided black it had 

 before. Its weight was 1*02 gr. 

 Heated twice I put it twice more into the stove, and each time its 

 weight was diminished, so that the 5 gr. of wood were 

 reduced at last to 0*27 of a gr., or about a twentieth of the 

 original weight. 

 Charcoal may I am persuaded, that I should have diminished it still 

 by a^heat 6 be- tnore » ^ * had continued the experiment longer: but it 

 low combusti- has been tried long enough to establish this remarkable 

 fact, that charcoal can be dissipated by a heat much less than 

 has been considered necessary to burn it. 

 ■Experiment It may be supposed, that I was very desirous of knowing 



«harcoai mm0n wnetner tne saine thing would occur to charcoal already 

 formed by the usual process. Accordingly 1 took a 

 piece of charcoal from my kitchen, heated it to a strong 

 red heat, and, while it was still red, put it into a marble 

 mortar, and powdered it. Having passed it through a sieve, 

 1 took 4*03 gr. of the powder, placed it in the saucer, 

 heated it in the stove twelve hours, and then left it twelve 

 hours to cool. . On taking it out it weighed but 3*81 gr. 

 A second ex- As this powdered charcoal was nothing but a collection 

 of small bits of charcoal, which were in contact with the air 

 only by a very small surface compared with that of the 



hsavings, 



