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was found to reduce the volume of oxygen gas, as 
well as living matter, in which case no saline sub- 
stances could have been materially concerned. 
611. In the example of charcoal, also, we possess 
facts which bear a near analogy to the circumstances 
under consideration. Scheele, Priestley, and Fon- 
tana remarked, that charcoal, after having been heat- 
ed, possessed the singular property of attracting and 
condensing air ; and that neither the air nor the 
charcoal suffered, in consequence, any change in 
their chemical properties. These experiments were 
repeated by Morozzo, who heated pieces of charcoal 
of a determinate size, and then passed them, in an 
ignited state, into tubes of mercury, where they re- 
mained till they became cold. Different gases were 
then passed up into the tubes, and were attracted and 
condensed in very different proportions. Atmosphe- 
ric air was condensed in a proportion three times 
greater than the bulk of charcoal employed ; hydro- 
gen and oxygen in a bulk nearly double that of the 
charcoal ; and carbonic and muriatic acid gases, am- 
monia, and sulphuretted hydrogen, in a bulk about 
eleven times as great. These experiments were re- 
peated by Rouppe and Van Noorden, who employed 
an apparatus, in which the ignited charcoal was al- 
lowed to cool, without being plunged in mercury, 
or exposed to the contact of air. Atmospheric air 
and oxygen were then condensed by it in a volume 
about three times greater than the piece of charcoal 
employed ; nitrogen and hydrogen gases in a some- 
what smaller proportion ; nitric oxide gas in a bulk 
more than eight times as great j and carbonic acid 
