242 Observations on the Alsorption of [Ocr. 
quence of this penetration, and forms water, and nitrous or ammo- 
niacal salts. 
The experiments which I have made in order to answer some of 
these questions I shall arrange in three sections. The first section 
contains my experiments on the condensation of pure unmixed 
gases by solid bodies; the second, my experiments on the absorp- 
tion of mixed gases by solid bodies; in the third, I shall state some 
observations on the absorption of gases by liquids. 
SEcTion First. 
ABSORPTION OF UNMIXED GASES BY SOLID BODIES. 
1. Amount of the Condensation of different Gases by Charcoal. 
Of all solid bodies, charcoal is the most remarkable in its action 
on the gases. It was a discovery of Fontana that red-hot charcoal, 
cooled by plunging it under mercury, or by any other method which 
precludes the contact of the air, possesses the remarkable property 
of absorbing more than its own volume of various gases. Count 
Morozzo remarked that this absorption is different according to the 
different gases and to the kind of charcoal used; and he made ex- 
periments which, when properly repeated, place this truth in a 
clear point of view. He allowed various gases, in exactly the same 
circumstances, to be absorbed by charcoal and other porous bodies, 
as pumice, brick, &c. It appeared to him that the gases absorbed 
by these last bodies underwent no condensation. Hence the con- 
densation produced by charcoal was considered as a peculiar action 
of that body, the full clearing up of which was left to future natu- 
ralists. 
Morozzo, Rouppe, and Norden, employed various methods in 
their experiments to cool charcoal without plunging it under mer- 
cury; but the unavoidable introduction of atmospherical air was 
injurious to the accuracy of their trials. It was in their power, 
indeed, to try the absorption of gases by charcoal ever water; but: 
the presence of water, as I shall show hereafter, diminished the | 
condensation of the gases, and introduced some inaccuracies inte 
their experiments. 
Iu my experiments the red-hot charcoal was plunged under mer- 
cury, and introduced into the gas to be absorbed after it was cool, 
without ever coming in contact with atmospherical air. All my 
experiments were made with the charcoal of box-wood. Its powers 
of absorbing are not only very remarkable, but it absorbs so little 
mercury during the cooling that it still readily swims on water. 
The following experiments were made between the temperatures 
of 52° and 56°, and under a barometrical pressure of 284 inches of 
mercury. The numbers are almost always means of several experi- 
ments ; for two pieces of the very same charcoal introduced into the 
game gas seldom give the same absorption. ‘The numbers refer to 
the volume of the charcoal, which is considered as unity. 
