than all the reft of t 
! 5°2 ] 
le mines. Some of the work- 
men, having left an iron (hovel in the ftream, found 
it fome weeks after incrufted with copper, infomuch 
that they thought it converted into copp>er. This 
gave the hint of laying bars of iron in thefe ftreams, 
which is done in the following manner : 
Oblong pits arc dug, ten feet long, four wide, and 
eight deep : the bottom laid with fmooth flags j the 
(ides built up with ftone and lime, with wooden rude 
beams acrofi> the pits to lay the iron bars on. Chains 
of thefe pits are continued along the ftream, as far as 
the directors pleafe ; for the water never abates of its 
quality, if it were convey’d from pit to pit thro’ a 
thoufand. Soon after the iron bars are laid in thefe 
pits, they contract a copper ruft, which, by degrees, in- 
tirely eats away the iron. The copper, which is in 
the water, being thus continually attracted and fixed 
by the iron, fubfides to the bottom of the pit. To 
baften this diflolution, the iron bars are fometimes 
taken up, and the ruft rubb’d off them into die pit. 
In the fpace of twelve months the whole bar is com- 
monly diflolved, if the iron be foft ; for fteel or 
hard iron will not do here. The ftream is then 
turn’d off the pits ; and the men with (hovels throw 
up the copper, which lies on the flag at the bottom, 
like reddifti mud. This mud, being laid in an heap, 
and as foon as dry, becomes a reddifli duft 3 of which 
I fend your lordlhip an ounce, that I took up on the 
fpot. It is then fmelted into copper. 
This being the apparatus, the produdt is thus. 
One ton of iron in bars produces a ton and 19 hun- 
dred and an half weight of this copper mud or duft. 
Each ton of this mud produces, when fmelted, 16 
hundred 
