o g Q Mr. ICeir’s Experiments and Obfervattons on 
then, that the liquor had not loft its power of atfting owfrejh 
iron, although it ceafed to act on that piece which had been 
expofed to it. 
15. To one of the pieces of iron which had been employed 
in the precipitation of a folution of filver, and from \\hich 
the folution, no longer capable of a fling upon it, had been 
poured off, I added fome phlogifticated folution of ill ver which 
had never been expofed to the aflion ot iron, but no precipi- 
tation happened. It appeared then, that the iron itielf, by 
having been once employed to precipitate a folution 01 lihcr, 
was rendered incapable ot any further aft ion on any folution 
of filver. And it is to be oblerved, that this alteration was 
produced without the lead diminution of its metallic fplen- 
dour, or change of colour. The alteration, howevei, was 
only fuperficial, as may be fuppofed ; for by feraping off its 
altered coat, it was again rendered capable of acting on a folu- 
tion of filver. To avoid circumlocution, I (hall call iron thus 
a ffefted, altered iron ; and iron which is clean, and has not 
been altered, frejh iron. 
x6. To a phlogifticated folution of filver, in which a piede 
of bright altered iron lay, without aflioti, I added a piece of 
frefli iron, which was inftantly enveloped with a mats of pre- 
cipitated filver, and afted on as ufual ; but what is very 
'remarkable, in about a quarter of a minute, or lefs, the 
altered iron fuddenly was covered with another coat of 
precipitated filver, and was now afled on by the acid folution 
like the frefh piece. I11 a little time the filver precipitate was 
re-diffolved, as ufual, and the two pieces of iron were reduced 
to an altered ftate. When a frefh piece of iron was then held 
in the liquor, fo as not to touch the two pieces of altered iron* 
they were neverthelefs foon afted upon by the acid folution, 
6 ' “ d 
I 
