EHRENBERG ON METEORIC ASHES IN BARBADOES. 23 
From these facts the following conclusions may be drawn :— 
1, The May-dust of Barbadoes in 1812, which formerly was only 
conjecturally derived from the island of St. Vincent, and which even 
Thomson’s analysis did not characterize as volcanic, has now, by my 
method of precise microscopic analysis, been scientifically determined 
to consist of pumice-dust and of crystals (very probably of pyroxene), 
so that its connection with the eruption on St. Vincent is now proved 
from the substance itself, 
2. One of the greatest and most interesting showers of volcanic 
dust which can be traced back to its origin, has now been shown to 
contain organic matter. 
3. The organic bodies im volcanic ashes are not only always found 
in the commencement of an eruption, but appear in this majestic 
outburst even at its conclusion, and consequently are probably not 
derived from the mere external surface. They are also, though the 
molten and baked condition of the ejected matter is very unfavour- 
able to the observation of its original condition, probably intimately 
and abundantly mixed with it. 
4. The organic portions of the Barbadoes’ May-dust present no 
such peculiarity of form as to withdraw them from the middle or 
more recent periods in the formation of the earth, and to consign 
them to a more ancient period in which other laws prevailed. The 
are chiefly forms well-known since the tertiary period, and still ex- 
isting. 
5. The distinct organic bodies are entirely and solely species 
known as freshwater and continental forms. There does not occur 
among them a single marine form. 
6. As the island of St. Vincent has no snow mountains, also no 
large rivers or marshes, which could furnish an abundant superficial 
supply of this muddy matter, it appears in this case that the matter 
which could by any possibility be drawn in from the surface bears no 
proportion to that thrown out, so that this method of explaining it 
is not applicable. 
7. The access of sea-water in order to excite the activity of the 
volcano on St. Vincent’s is decided in the negative, by the absence of 
all marine organisms in the ejected matter, which contains so many 
of freshwater origin. But, in like manner, there is no probability of 
the infiltration of meteoric water from the arid vicinity of the vol- 
cano. But how wide do its roots extend? Must we not actually 
imagine a direct subterranean communication with the remote Quito, 
or at least with Venezuela? The great geologist of those lands, 
Alexander von Humboldt, has long expressed this opinion on general 
grounds :—Relation Histor. vol. i. p.15. Compare L. von Buch, 
Canar. Inseln, pp. 313, 399, 400. 
8. Is there a deposit of moist coal, or turf, or bituminous tripoli 
under Morne Garou, which the lava, forcing its way from the inte- 
rior, continued to eject from the beginning to the end of the erup- 
tion ? 
[J. N.] 
