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DISCOVERY OF A WHITE FOSSIL POWDER. 259 
medium. The specimen he received was a compact mass, 
and had a coarse and somewhat fibrous fracture, but could 
easily be pulverized, and when rubbed between the finger 
and thumb, it had no grittiness, but seemed to be an impal- 
pable powder, and when it was then blown into the air, it 
floated about almost like wood-ashes. Magnified figures of 
this powder are given, consisting of six different shapes, but 
the bulk of it is stated to be long linear spicular bodies, with 
a small per-centage of others of an oblong or square shape, or 
oval, or with smaller ends. This powder was not acted upon by 
nitric, muriatic, or sulphuric acids and was indestructible by fire. 
Now, it is a well known fact, that many families of vegeta- 
bles, especially the Gramineze and Carices, take up a large 
quantity of silica in a fluid state through their roots, and deposit 
-itin an unorganized shape, within and upon their stems and 
leaves, In fact, beautiful vegetable skeletons of such plants 
may be procured by burning away all the carbonaceous matter, 
after which a complete counterpart of the original structure, as 
white as snow, is left in the indestructible siliceous framework. 
It is also known, that silica in considerable abundance enters 
into the composition of certain tribes of Alge, Confervee, &c., 
and may be seen in their ashes after burning, in an organ- 
ized and unaltered state. On submitting some minute 
Parasitic plants of these families to a red heat, and afterwards 
examining them in the microscope, Dr Drummond found 
that the ashes of one of them, the Diatoma elongata, which 
abounds in a small drain in the neighbourhood of Belfast, 
consisted of oblong joints precisely similar to the spicular 
bodies that formed so large a proportion of the Fossil Powder 
from Lough Island Reavey, and he came to the conclusion, 
that the latter is composed of the siliceous skeletons of por- 
tions of these minute vegetables, and analogous to what had - 
Previously been found in several places, both in the Old and 
New World. oun 
As yet, however, it was not known that this highly curious, - ; v 
E though app arently uninteresting powder was to be found in 5 
England, and this discovery is due to the researches of Mr - j 
