the D if elution of Metals in Acids . 
A folution of fiver, which did not a£t on iron, upon being 
very much diluted, and having a piece of iron i miner fed in it, 
during feverai hours, gave a precipitate of fiver in the form of 
a black powder. 
SECTION lit. 
On the alterations which iron or its furface undergoes by the action 
cf a foliation of fiver in nitrous add , or of a pure concentrated 
nitrous acid . 
13. It has been laid, that when iron is expofed to the adtloii 
of a phlogiftica.ted folution of fiver, it inftantly precipitates 
the fil ver, is itfeif acted upon or difiolved by the acid folution 
during a certain time, longer or fhorter, according to the de- 
gree of phlogiftication, quantity of fuperabundant acid, and 
other circumftances, and that at length the folution of the 
iron ceafes 5 the fiver precipitate is re-difioved, if there is fu- 
perfluous acid ; the liquor becomes clear again, but only ren- 
dered a little browner by ijs having diffblved fome iron 3 
while the piece of iron remains bright and undifturbed at the 
bottom of the liquor, where it is no longer able to affedt the 
folution of fiver. 
14* I poured a part of the phlogiflicated folution of filvef 
which had pafled through thefe changes, and which had 
ceafed to act upon the piece of iron, into another glafs, and 
dropped another piece of frefh iron wire into the liquor ; upon 
which I obferved a precipitation of fiver, a folution of part of 
the iron, a rediffolution of the precipitated fiver, and a cefla- 
tion of all thefe phenomena, with the iron remaining bright 
and quiet at the bottom of the liquor, as before. It appeared 
D d d % then* 
