. 
1815.J the Gases ly different Bodies. 243 
Charcoal of box-wood absorbs, of 
Volumes, 
Ammoniacal gas ..+e-eeee ee deeeeeeeee 90 
Muriatic acid...... cece sees cece ene ee 85) 
Sulphurous acid... 2... 0s sees eee eee ee 65 
Sulphureted hydrogen ......-e++ee+e+ 59. 
Nitrous oxide ........cccceeceee senses 40 
Carbonic acid (2)... ee pe cece eee ee BS 
Olefiant gas ....ee es ce eer reece eree BD 
Carbonic oxide.,.c..0sssseeceesesenes DAZ 
Oxygen... secre eeeree re ceernreces FH 
rR et Sat dy tmastlad ee eheighalye, gre Huh 
Oxy-carbureted hydrogen* ......s..++5 5 
Hydrogen ......0cee ee ereeeeeeeeceee 195 
Box-wood charcoal absorbs 38 times its volume of nitrous acid 
gas ; but as a portion of this gas is decomposed, the result cannot 
be compared with those contained in the preceding table. 
In all these gases the absorption terminated at the end of 24 or 
36 hours, so that it was not increased by allowing the charcoal to 
remain longer in contact with the gas. Oxygen gas alone consti- 
tutes an exception to this general rule; for its absorption seems to 
continue for several years. The reason is, that a small quantity of 
carbonic acid is always forming, of which charcoal absorbs a much 
greater quantity than it does.of oxygen gas. ‘This formation goes 
on so slowly atthe common temperature of the air, that several 
years elapse before as much carbonic acid gas is generated as is 
sufficient to saturate the charcoal. I shall state below, in a note, 
the facts which led me to this conclusion. t It is exceedingly pro- 
* I obtained the owy-carbureted hydrogen, which I employed in all my experi- 
ments, by distilling moist charcoal. Its specific gravity, after separating the car- 
bonic acid, was 0°3326, that of air being 1. 100 measures of this gas require for 
combustion 60°18 measures of oxygen gas, and form 31°5 measures of carbonic 
acid gas, Hence its composition is as follows: 
CADOD wie od svi iv cease So scat ae etoaae 
igen Petites vocene ct adios paves RBOD 
Bydeonenii es tye seni veel tend he 16OD 
DRAG rial dilen e wiegd's die tiedeavcseisse T4163 
100-00 
4 On the Formation of Carbonic Acid Gas at the common Temperature from Charcoal 
and Oxygen, 
It has hitherto been supposed that charcoal only unites with oxygen at a tempe- 
rature not much below u red heat; but I think that I have remarked that the 
common temperature of tlie air is sufficient for this union, As this observation is 
important, and may be contradicted, it will be permitted to me, { presume, to 
stale more particularly the nature of my observations, 
A volume of box-wood charcoal quenched in mercury that in 24 hours had ab- 
pod 94 volumes of dry oxygen gas, was left for 18 months in the same gas 
ing over mercury. In two months the absorptian was 11 volumes ; in 1A 
months it was 13 volumes. 1t always became slower as the time advanced, and 
was not completed in 18 months, J put an end to the experiment in order to 
Q 2 
