a3: Reply of Dr. Daubeny to Prof. Bischof. 
Arr. V.—Reply of Dr. Dauseny to Prof. Bischof’s Objections to 
the Chemical Theory of Volcanos.—Edinb. New Phil. Jour. 
for April, 1839. ; 
Prof. Daveeny after referring to an article of his in the Edinb, 
Jour. for 1832, and to the article Volcanic Geology, in the Ency- 
clop. Metro., proceeds to vindicate his own views in regard to 
the chemical theory of volcanos, by replying as follows, to the 
objections against it. 
1st Oljection.—It is not true that volcanos are always near the sea. 
Pesckan, in the centre of Asia, is 260 geographical miles from 
any great sea, and yet has given rise to streams of lava within the 
period of our history. It also lies 25 geographical miles from the 
lake of 'Timartu or Issikul, which is not twice as large as the lake 
of Geneva. 
The volcano of Turfan also is surrounded by very inconsidera- 
ble lakes. 
Answer.—The general connection of voleanic action with, ora 
proximity to, large masses of salt or fresh water, is all that seems 
required by the conditions of our theory. 
Now, in proof of this general proximity, it may be remarked, 
that out of a catalogue of ‘no less than'163 active vents enume- 
rated by M. Arago, as occurring in various parts of the known 
world, all excepting two or three in different parts of America, 
and about the same number of which we possess very imperfect 
information, in Central Asia, are within a short distance at least 
of the ocean. It is even found that the very excepted cases, when 
examined, tend to confirm the rule, being so situated, that their 
connection, either with the ocean or with inland seas that may 
supply its place, becomes a matter of fair inference. In proof of 
this, we need only refer to the descriptions given by Humboldt of 
Jorullo; from which it appears, that distant as this mountain may 
be both from the Atlantic and Pacific Oceans, it is nevertheless 
connected with one or both through the medium of a chain of 
volcanic eminences; and even the voleanos of Tartary, whose 
existence in an active condition is more problematical, may be 
connected with some of those extensive salt lakes which seem 0 
abound in the depressed portion of Central Asia. 
2d Objection.—Atmospheric air cannot gain admittance to the 
focus of a volcano, because there must be an enormous force act- 
