178 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Carbon dioxide of submarine volcanic origin. — The carbon dioxide 
ordinarily found in the sea is not free but combined in carbonates and 
bicarbonates. | 
In the case of carbon dioxide of volcanic origin discharged in the sea, 
it might remain chemically dissolved in the water, (CH,O + CO,) = 
(Н, CO3), but as soon as it came in contact with calcium or magnesium, 
the carbon dioxide would dissolve the lime carbonate, whether in the 
calcareous shells of living mollusks, corals, and crustaceans, or in the 
broken fragments of dead ones on or near the shores. A bicarbonate 
would be formed and held in solution until precipitated out or other- 
wise removed as a carbonate. 
It is but natural that one should object at the outset to a theory that 
seems to be so far-fetched — to a source go out of the ordinary course of 
events as does the one here suggested. But the source is really not so 
extraordinary'as it at first appears. 
The most valuable observations upon the gases emitted by voleanic 
eruptions with which I am acquainted is that of Fouqué upon “ Santorin 
et ses eruptions,” published at Paris in 1879. In his study of that 
interesting locality M. Fouqué found that — 
a. The carbonic acid discharges became more and more marked after 
the seasons of greatest volcanic activity. 
б. That the compositions and temperatures of gases were but little 
affected by passing through waters (p. 229). 
с. That variation of the gases is the same for subaqueous as for 
subaerial volcanoes (p. viii). 
The pouring out of volcanic eruptions beneath the ocean is not an 
uncommon occurrence. Indeed, Sir. Archibald Geikie lately remarked 
that “ With regard to the supposed impossibility of lavas having flowed 
under the sea, he could only observe that no facts in the geological 
history of Britain were more abundantly proved than that from the 
earliest Palaeozoic periods the vast majority of the volcanic eruptions in 
our region have been submarine.” 1, . . Sometimes the products of these 
eruptions rise above the water’s surface, forming islands, as in the cases 
of Graham’s Island in the Mediterranean Sea,? islands off the west coast 
of Iceland, and Bogoslof off the island of Unalaska. 
The island of Bogoslof, as it is now called, was first described by 
Langsdorff. He says that in 1795 the people of Unalaska observed the 
1 Quar. Journ. Geol. Soc., May, 1898, LIV., р. 233. 
2 Н. J. Johnston-Lavis. For bibliography of this island, see The south Italian 
volcanoes, p. 105-107. Naples, 1891. 
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