S34 Observations on the Absorption of [Nov. 
same proportion in which the bulks stand, which the single gases 
occupy in the charcoal? According to paragraph 1, one volume of 
box-wood charcoal freed from air absorbs 9°2 volumes of oxygen 
and 1°75 of hydrogen gases. According to these proportions, 7°5 
volumes of oxygen ought to have expelled 1:42 volumes of hydrogen. 
But as the quantity expelled was only one volume, we see that the 
presence of hydrogen gas increases the condensation of oxygen gas 
in charcoal, which retains at the same time 0°75 of hydrogen aad 
7:5 volumes of oxygen gas. It will be obvious, without my pointing 
it out, that the bulks 0°75 and 7°5 are by no means in the requisite 
proportion to one another for forming water. 
‘To follow out this subject still further, I put a piece of charcoal 
saturated with the two gases (without allowing it to come in contact 
with the air) into a jar filled with mercury, and containing a little 
water. The charcoal absorbed this water; and in 48 hours allowed 
3-11 volumes of oxygen and 0°13 of hydrogen gas:to escape. New 
according to paragraph 2, charcoal which has absorbed 9°2 volumes 
of oxygen when placed in contact with water lets go 3°2 volumes, 
and still therefore retains six volumes. While in the present case, 
in consequence of the presence of hydrogen in charcoal of the 7°5 
volumes of oxygen, 3°il volumes are disengaged by the water, and 
only 4°39 volumes remain bebind. ‘These two gases, therefore, 
have not united in the proportions which constitute water. Besides 
this, I have extricated an additional quantity of oxygen and hy- 
drogen gases out of the same charcoal, by boiling it in water. It is 
true that the temperature is not sufficiently high to expel the whole 
of the gases: but this is the case likewise when only one gas is 
present. 
The following experiment, which is the reverse of the preceding, 
still further increases the doubts about the formation of water by 
the union of oxygen and hydrogen in charcoal at the ordinary tem- 
perature of the atmosphere. . 
Introduction of a piece of Charcoal saturated with Oxygen into «@ 
: Receiver containing Aydrogen Gas. 
According to Messrs. Rouppe and Norden, the appearances which 
they describe take place likewise in this case. ‘There is the same. 
diminution ef the bulk of the gas in the receiver, the temperature 
of the charcoal increases, water is formed, which first appears in 
vapour, and then falls upon the sides of the receiver in drops. But 
I have obtained quite different results. The quantity of gas round 
the charcoal increased, the thermometer sank, and no formation of 
water was perceptible. 
A volume of box-wood charcoal, which, after exposure to a red 
heat, had absorbed 9°2 voluines of oxygen at the temperature of 
52°, was put into 15-6 volumes of hydrogen gas. The bulk of the 
gas increased 3°21 volumes; so that it amounted to 18°51 volumes : 
and a thermometer, which at the beginning of the process had been, 
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