Mr. Tennant on the Composition of Emery. 401 
As such emery can easily be had of uniform quality in large 
pieces, I procured the powder employed in this experiment, by 
rubbing two pieces against each other. 
From 25 grains of emery, similar in appearance to the pre- 
ceding, but which had been digested with marine acid previous 
to the action of the alkali, I had, 
Of argillaceous earth 
164 
per cent. 
65,6 
Siliceous earth 
,8 
3 ’ 2 
Iron 
2, 
8, 
Not dissolved 
18,0 
23.7 
£»4j>8. 
The hardness of emery, as 
far as I could judge by its cutting 
rock crystal and flint, appeared to be equal to that of diamond 
spar. The latter could not be scratched by the former ; but, as 
emery has not a surface sufficiently polished to render a mark 
visible, the converse of this could not be tried. 
All the emery which is used in England, is said to be brought 
from the Islands of the Archipelago, and principally from 
Naxos. In those places, it is probably very abundant ; as the 
price of it in London, which I was told was 8 or 10 shillings 
.. the hundred weight, appears little more than sufficient for the 
charges of carriage. Though I saw a very large quantity in one 
place, (more than a thousand hundred weight,) I could not find 
any pieces of a crystallized form ; possibly the great proportion 
of iron usually mixed with it, may prevent its crystallization. 
The whole consisted of angular blocks incrusted with iron ore, 
sometimes of an octaedral form, with pyrites, and very often 
with mica. The latter frequently penetrates the whole sub- 
stance of the mass, giving it, ^hen broken, a silvery appearance. 
