Pee eG er Ses y SS Ys Volcanos. — oF 
:: . ~ 
— ie =—— ad MOeasieuss 
ated and compe is deduced 7 oo from what 
rn the surface, as is explained in the article itself. - 
; e best answer to this last, and perhaps to all the 
ther objections, is to copy here an extract of the Puizoso- 
PHICAL TRANSACTIONS, 1826. On Compression of Atmos- 
pheric Air, by Paka. “In the course of my experiments 
on the compression of atmospheric air, | observed a curious 
fact, which induced me to extend the experiment ; viz: that 
of the air beginning to po at a pressure of five hun- 
dred atmospheres, evidently by a partial iwetaction, which 
is indicated by the quicksi ae not se down toa level 
with its surface. At an increased es of. aie drungeed 
Le lege the quicksilver was suspended about one-eighth 
of the volume up the tube or gasometer. At eight hundred 
siriedephatee it remained about one-third up the tube ; at one 
thousand atmospheres, two-thirds up the tube, and small 
globules of liquid began to form about the top of it; at 
twelve hundred atmospheres the quicksilver remained three- 
quarters up the tube, and a beautiful transparent liquid was 
seen on the surface of oe quicksilver, i in quantity about 51,4 
part of the column of air. 
_ From these experiments, it rota as a fact, that under 
. the t of e hundred a ospheres, two-thirds of the 
air is still under an aerial + ati although its density is then 
equal to that of water; and even at twelve hundred, when it 
is much denser, one-third of it is not liquefied. This is ate 
tient for us to maintain that under the pressure of the sea : 
layer of air may produce the effects we have endeavored to 
describe. 
. B. We regret that the beautiful experiments of Mr. 
Perkins on the compressibility of water have not been per- 
ormed upon water at forty degrees of temperature, its great- 
est natural condensation, instead of fifty degrees, and upon 
water entirely deprived of air; this would be a still greater 
proof that water itself is condensed, and not the air it con- 
tains, or not that the caloric, which dilates it, is repelled by 
compression. By similar reasons, the compression of air 
should have been performed on air perfectly dry, that an 
not be objected that some water has been a 
experiment performed also on oxygen a tote separately 
to show, whether these gases liquefy sad at ae same p. 
sure when they are not combined as in the a tmospheri 
