C 185 3 
fore it quits the copper, corrodes the iron, and changes 
it into a vitriol, which is again diffolv’d, and carried 
off in the ftream continually flowing from the pits ; 
whilft the copper, deferted by the acid, falls, by its 
fpecific gravity, to the bottom of the pits. 
•By this account it is evident, that this admirable 
procels is a Ample precipitation of the copper, by 
means of the iron. Hence it has been improperly 
called a tranfmutation of iron into copper. But, left 
any difficulty ffiould ftill remain, concerning the con- 
fumption of the large quantities of iron put into the 
pits, I fhall add the following obfervations, to fhew, 
, that it is diffolved and carried off in the water. 
Obfervation 1. The water in the pits is cover’d 
with a thick feum, occaflon’d by the air- bubbles con- 
ftantly l'iflng, and burfting on the furface j which is 
an evident ftgn of the folution of the iron. 
Obf 2. The iron is gradually confum’d in the 
pits, and abounds with irregular depreffions, like old 
iron : a ftrong fymptom of its being corroded by an 
acid. 
Obf 3, The chanel of the flream running from 
the pits is furr’d with red oker, which, after being 
roafted in a ftrong Are, was attracted by the magnet. 
As this oker is only found in the ftream below the 
pits, it appears to be part of the iron diffolv’d in the 
water. 
Obf. 4. The quantity of copper found in the pits, 
after the iron difappears, is generally greater than that 
of the iron when Arft put in : for the proprietors af- 
fured me, that fometimes a ton of iron will produce, 
or rather precipitate, a ton and half of copper. 
A a This 
