Just recently, I found some of a metal chain, thin, like the sort used for jewellery, its very heavy and at first I thought it might be silver, it
certainly looks quite like silver.
Funny thing is, then heated in a lighter flame, it makes violent cracking and popping sounds, and shoots out gouts of hot metal for quite some
distance.
Any idea of what it might be? its dark grey like silver, heavy, and quite hard.
I could really use some help in identifying the metal, i have never seen anything like it, it doesn't melt in a lighter flame, but remains solid
whilst spitting off the little jets of molten metal, which came as quiet a nasty surprise when I heated the thing
Edit: It DOES just about melt in a lighter flame, but only on very prolonged heating for a few minutes or more forming a grayish-black oxide layer on
the surface, which makes me think theres Pb in there somewhere, and imparts a barium-green color to a flame test, smells kind of slightly perfumy when
heated and cooled.
[Edited on 22-10-2004 by Reverend Necroticus Rex]
[Edited on 22-10-2004 by Reverend Necroticus Rex]JohnWW - 21-10-2004 at 23:59
If it is a silver-like jewellery chain, but much heavier than Ag or Ni or cupro-nickel (or "German silver", a lustrous white Ni-Cu-Zn
alloy), as you say, I would be inclined to think that it might be a Pt or Pt-Ir alloy. If it also gave off a penetrating smell when heated, it could
be Os or an Os-Ir or Os-Pt alloy (which would give off OsO4). Another possibility is "white gold", an Au-Ag-Pt alloy. Alloys of Pb are too
soft and of insufficient strength to be used to make chains.
Fort a start, you could determine its density, by weighing it first in air, and then either finding the volume of water it displaces directly or else
weighing it again while suspended in water. Other non-destructive tests would be the Mohr hardness, electrical conductivity, and X-ray fluorescence
and (if it has a sufficiently high melting point) arc emission spectroscopy for its composition. If the chain has a large flat surface anywhere on its
links and can be polished, its reflectivity of light could be photometrically determined.Reverend Necroticus Rex - 22-10-2004 at 16:47
I haven't got any fancy equipment for tests like those, even breaking a test tube is a pretty big setback for me
The smell isn't penetrating or irritating, only a very slight odor of perfume when heated, sort of flowery.
I don't think its one of the platinum group metals, as it melts just about, in a lighter flame under prolonged heating.
The thing that gets me, is the spitting of jets of molten metal when heated, even in a lighet flame, small gouts of hot metal get flung a good couple
of feet away with a cracking noise.JohnWW - 22-10-2004 at 17:47
You should certainly be able to determine the density of the metal, using the method I described, which requires only a sufficiently sensitive balance
(a spring balance would be needed for weighing it immersed in water) and a beaker.
"Spitting of jets of metal" when heated? This may indicate that it is plated or "rolled" metal, with the more tarnish-resistant
and valuable metal used for plating by electrolysis or dipping in molten metal. Heating the article would result in differential expansion of the base
and plating metals, due to different coefficients of thermal expansion, which could result in the two metals separating.uber luminal - 22-10-2004 at 23:21
Quote:
Originally posted by JohnWW
which requires only a sufficiently sensitive balance (a spring balance would be needed for weighing it immersed in water) and a beaker.
why would you need a spring balance? I dont follow. Iv done it perfectly well with a digital postal scale.
as for finding out what the metal is on low budget, desnisty is the key. Once you know this, you know whats not in it. then you can see what elements
or alloys could possibly be left, and from there you can make a good guess.
My guess, its some pewter alloy. (nice shiny silver, lower MP)
Oh, does it discolor if you heat it a little bit? or where you have made it melt?
Possible that its something cheap (like zinc, which could pop and crackle and form white oxide) coated with something else.
tin and zinc oxides smell flowery in small ammounts.
[Edited on 23-10-2004 by uber luminal]chemoleo - 23-10-2004 at 19:49
Possibly it is (I am not sure whether the people above meant the same thing) simply a hard layer of stainless steel, or some silver alloy, or
whatever; while there is some cheap metal filler underneath, i.e. some lead/tin mixture. This would explain the heaviness, and yet the comparable
hardness.
In fact, the 'jets' support this, the outer 'hull' does initially not melt, while the inner stuff melts, expands, and finds a way
through the softened (but still solid) outer layer - under pressure by necessity because otherwise the outer layer wouldn't crack. Then, once
pressure gets back to normal, it stops squirting.. and the outher layer starts to crumble/melt eventually too.
This is quite easily tested. Just subject the squirted jet stuff, and the remainder to various chemicals (acids, strong bases) and observe the
respective products. I'd bet that you'lll find different products if you analyse carefully.
Edit: Omg, just noticed, 1000 posts! I've come of age!
