GASES ABSORBED BY CHARCOAL. ]3 



tried with charcoal in my machine, eight inches and fix lines Oxigen gas. 

 were abforbed : this great abforption furprized me ; for in my 

 firft experiments, in 1783, made in clofed tubes. I had had 

 but a very (mall one : I therefore found no difficulty in attri- 

 buting it to my matrafs' having been melted towards the clofe 

 of the operation, which made me fufpect that my gas had 

 been fpoiled by the nitrous acid; and I repeated the experi- 

 ment with great care. 



26th. I then took oxigen gas which had been obtained from 

 red precipitate with great attention, and had been prepared 

 in the laboratory of Do&or Bonvoifin; what was my aftonifh- 

 ment at obferving that, in thirty-fix hours, the abforption 

 amounted to twelve inches and eight lines, and that it conti- 

 nued lor feveral days: in forty-eight hours it was fourteen 

 inches fix lines ; in four days, fifteen inches two lines ; in five 

 days, fixteen inches four lines; and, finally, in three days 

 more, the gas was entirely abforbed.- 



27th. This experiment was too interefiing to omit repeat- 

 ing it with the greateft pofiible precifion. 



I therefore took fome of the fame oxigen gas, and the ab- 

 forption was twelve inches three lines in the firft four hours; 

 in forty-eight hours, it was thirteen inches fix lines; in three 

 days, fourteen inches five lines; at the end of the fourth day, 

 it was fifteen inches three lines? of the fifth, fixteen inches; 

 ■of the fixth, fixteen inches feven lines; of the fevenlh, feven- 

 teen inches two lines ; finally, on the eighth day the gas was 

 entirely abforbed. 



28th. I repeated the fame experiment on oxigen gas ob- 

 tained from water expofed to iha fun, in which I had put 

 three ounces of charcoal-powder*; in this gas, which was 

 very pure, the abforptions took place in the fame manner. 



29th. Thefe fa<5ts will furprife thofe who, having made 

 their experiments on oxigen gas in tubes clofed hermetically, 

 and by paffing the charcoal through the mercury, obtained 

 only very fmall abforptions, which never exceeded three inches 



* In the twelfth volume of the Italian Society, I have inferted a 

 memoir on the property which charcoal mixed with water has of de- 

 veloping one-third mere of oxigen gas, of a fuperior quality to that 

 obtained from pure water : In this memoir I prove, that a part of 

 this oxigen gas is produced by the charcoal, which communicates 

 the principle of fire to the air contained in the water. 



three 



