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within a stone thus formed of a silicious crust, it is the stone named 
by the ancients Elites, from its being supposed to be frequently 
found in the nests of eagles ; the contained stone being termed the 
callimus. If the crust is empty, or contains loose sand, or other 
earthy substances, or is filled by any other kind of earth, it is termed 
simply a geode but if it contains water, it is then distinguished by 
the name enhydros. 
It cannot have escaped your observation, that the absence of 
water from the interior of these silicious nodules is a circumstance, 
on which Mr. Playfair chiefly founds his hypothesis; but the fact 
really is, that water is very frequently found in these nodules ; and 
that the stone, thus termed enhydros, is very frequently mentioned 
by lithologists. The German mineralogists speak of them in such 
a manner, as by no means to imply their being of rare occurrence. 
In Germany, indeed, from the abundance in which silicious and 
agatine nodules there exist, they might be expected to be met with : 
but even in our own country they are also frequently seen. They 
are found, I am informed, in and about the neighbourhood of St. 
Vincent’s rock, near Bristol ; and in no crystalline geode, which I 
have seen from St. Vincent’s rock, is there a single circumstance to 
lead to a doubt as to their having contained an aqueous fluid. Dr. 
Plott, in his History of Staffordshire, relates, that among the best 
sort of iron stones, called mush, are frequently found round, or oval, 
blackish and reddish stones, sometimes as big as the crown of one’s 
hat, hollow, and like a honeycomb within, and holding a pint of 
sweet liquor ; which, according to the colour of the comb within 
(whatever the stone be without) is either red or white ; and whether 
the one or the other, of a sweet sharp taste, very cold and cutting, 
yet greedily drank by the workmen. It is especially found in that 
sort of mine the country people call the white mine, which yields 
the best iron-stone, where the workmen commonly, upon breaking a 
stone, find it enclosed in the centre, sometimes to the quantity of a 
