16 



GASES ABSORBED BY CHARCOAL. 



Thefe experiments correfpond perfectly with thofe which 

 I have publifhed in my third memoir. I (hall difpenfe with the 

 relation of feveral other experiments which I have made on" 

 different woods, fuch as hazle, vine-twigs, &c. all of which 

 gave lefs abforptions. 

 of box ; I afterwards tried the charcoal of box wood, although it is a 



very compact wood; but fince Kirwan found that this wood 

 contains much more faline matter than any other wood, it 

 was defirable to fubmit it to experiment : its abforption, how- 

 ever, was conficlerable, and equal to that produced by beech- 

 wood. The greater or lefs quantity of faline matter in the 

 wood of which the charcoal is made, therefore, does not con- 

 tribute to the variations in the abforption. 

 of cork. 40th. I afterwards examined the charcoal of cork, which 



interefted me greatly, becaufe Cit. Odier, from the experi- 

 ments of Dr. Beddoes, has propofed it as a medicine : I was 

 defirous of examining whether it contained more of the prin- 

 ciple of fire than the others. I therefore charred cork ; but 

 it is fo light, that, after the charring, a piece of equal bulk 

 with that of the beech which I had ufed, weighed only three 

 grains : to bring thecircumftances to an equality, it was there- 

 fore necefTary to make the experiment with a piece of beech 

 charcoal which weighed three grains*: it was in atmolpheric 

 air it was tried. The following are the refulis : 



Three grains of beech charcoal produced an abforption of 

 one inch and nine lines. 



The charcoal from cork abforbed only nine lines. 

 The charcoal of 41 ft. According to my principles +, the charcoal of cork 

 cork contams niu fl. conla j n t| ie matter of fire more than any other charcoal; 



more of the . . . . , . ... 



principle of fire thus when it is necefiary to give it as a medicine, either m- 

 chan any other V vard!y or outwardly, it fhould be preferred to all the others ; 

 and I am of opinion that it is by oxidating, and not by difox- 

 idating, that it produces its aftonifhtng effects. Befides, we 

 have instances of fubftances which aft in this manner. The 

 oxigenated muriatic acid, far from abftra&ing the oxigen, is 



* The piecesof beech charcoal which I ufe, and which weigh 

 thirty-fix grains, are of the length of ten lines, and about five in 

 diameter. 



1 See my third memoir on charcoal. 



fuppofud 



