the Difolution of Metals in Acids. jS c 
and fuddenly covered with filver precipitate as before; and 
thefe phenomena may be repeated with the fame foliation of 
filver, until the fuperfluous acid of the folution becomes fa~ 
turated by the iron, and then the re-diffolution of the precipi- 
tated filver mu ft ceafe. 
17. I poured feme dephlogifticated nitrous acid on a piece 
of altered iron, without any adlion enfuing, although this acid 
readily afted on frefh iron, and when to the dephlogifticated 
nitrous acid, with a piece of altered iron lying immerfed in it, 
1 added a piece of frefh iron, this immediately began to dif- 
folve, and foon afterwards the altered iron was aded on alfa 
by the acid. 
18. I poured upon a piece of altered iron a folution of cop- 
per in nitrous acid ; but the copper was not precipitated by the 
iron ; neither did this iron precipitate copper from a folution of 
blue vitriol. 
19. Altered iron was aded on by a dilute phlogifticated ni- 
trous acid ; but not by a red concentrated acid, wiiich is 
known to be highly phlogifticated. 
20. I put fome pieces of clean frefh iron wire into a con- 
centrated and red fuming nitrous acid. No apparent adion 
enfued; but the iron was found to be altered in the fame man- 
ner as it is by a folution of filver ; that is, it was rendered 
incapable of being attacked either by a phlogifticated folution 
of filver, or by dephlogifticated nitrous acid. 
21. Iron was alfo altered by being immerfed fome little 
time in a faturated folution of filver, which did not fhew any 
vifible adion on it. 
22. The alteration thus produced on the iron is very fuper- 
ficial. The leaft rubbing expofes fome of the frefh iron be- 
neath 
