DISCOVERY OF A WHITE FOSSIL POWDER. 261 
abundance near Haxey, in the peat deposit of the neighbour- 
ing level of Hatfield Chase, and was informed by the farmers 
there, that wherever it occurred, the soil above it was very 
poor and unproductive. This fact is a strong confirmation 
of its being silica, such soils being proverbially sterile. 
In this stage of his knowledge, Mr Binney saw Dr Drum- 
mond’s account of the Powder from Lough Island Reavey, to 
which I have referred, and immediately recognised the deposit 
of Blyton Car to be analogous. Indeed, itis remarkable how 
closely the two descriptions coincide; and it will be observed, 
thatin both these cases, as wellasin that from the United States, 
the Powder was found under peat, and resisted the action of 
acids and of heat. He shortly afterwards procured a fresh 
supply from Lincolnshire, and submitted it to several friends; 
among others, he requested me to examine it closely, and 
= Communicate the result. The little acquaintance I had with 
the obscure, neglected, but pre-eminently beautiful, and ex- 
traordinary tribe of the Conferve, showed me on the first in- 
spection of the Powder, the high probability of its connexion 
with them; and a reference to some specimens in my own her- 
barium, and to magnified figures of others in the works of 
Greville, Sowerby, &c., soon convinced me that it was indeed 
the accumulated remains of myriads of these minute aquatic 
plants, purified by the decomposition of all their original 
vegetable matter, and effectually secured from contact with 
other impurities, by the superincumbent peat. The circum- 
stance of its occurrence between two beds of peat, may, I — 
think, be explained on the supposition of a slight change of 
level, by which the lowest bed has been submerged, and the - 
water in which the Conferwz flourished has remained long 
enough to allow the present accumulation of their remains. 
In time, however, the water has been driven off by the in- 
crease of the vegetables, which in their decay have formed 
the upper bed of peat, and covered up the powder. Such 
T changes of level, the result of subterranean movements, are — 1 
: - of frequent occurrence, and are familiar to geologists. pu 
As the tribe of plants which compose this department of — 
