ANNALS 
OF 
PHILOSOPHY. 
OCTOBER, 1815. 
ARTICLE I, 
Observations on the Alsorption of the Gases by different Bodies, 
By Theodore de Saussure. * 
We possess at present no accurate experiments on the question, 
whether a gas, when it penetrates into the pores of a solid body, 
undergoes any diminution of bulk in consequence of this penetra- 
tion, even when no chemical union takes place between the gas and 
the solid body? It is, for example, still unknown whether azotic 
or oxygen gas, which do not combine chemically with silica, un- 
dergo a diminution of their bulk when they penetrate into a porous 
silicious stone, as opal, hydrophane, or even sand-stone. If we 
allow that such diminution of bulk takes place, a number of other 
questions immediately present themselves. What influence has the 
size of the pores on this condensation? Are all gases equally con- 
densed by the same bodies? And what influence has the density of the 
gas on this condensation? hese inquiries become still more inte- 
resting when different gases are employed together. When two 
gases mixed equally are presented to a solid body, does it absorb 
them in equal quantities or not? And do the mixed gases, when 
condensed in solid bodies, enter into combinations which they would 
not form in a free state? It is obvious that such investigations may 
lead us to discover whether our atmosphere, when it penetrates into 
the interior of earthy bodies, becomes condensed merely in conse- 
* T have translated this important paper from Gilbert’s Annalen der Physik, 
vol. xlvii, p, 112, July, 1814. The original was read in the Geneva Society on 
the 16th of April, 1912, But I do not know where it was first published, Gilbert 
informs us that it was translated into German by Professor Horner, of Zurich,—T. 
Vor, VI, N° IV. Q 
