Hi!
I picked up a case from a Dupont Instrument recently from a friend who has a store selling sciency crap that can be used as household items. He often
gets all sorts of stuff in and the stuff that is not sellable in his designer homewares store i often buy off him if i want it.
Last week there was a small plastic Dupont Instruments case, sort of like the one that comes with a larger instrument. Opening it i found most of the
items missing except for a really good accurate flowmeter and some small plastic plugs. He gave it to me for free when i said i could use the flow
meter. Getting back to work i noticed a second smaller plastic case within the larger one and opened it to find 5 small metallic boats, kind of like
sample weighing boats. I immediately thought 'platinum'
So looking up the part number i find dupont instruments no longer exists and hence any part number references.
The part number is 901 083 901 on the 'boats
The larger case containing it all had a part number 902134-901
My email to Dupont has been automatically replied to but nilch from them after that.
Any ideas to figure out what foiled metallic material these are made from, they weigh ~1g each are ~30mm long x ~10mm wide x ~10mm deep trays with a
little handle on the backside? The metal is dull mid darkness grey, like punched platinum (or mild steel without oxidation). the foil is malleable
however a little stiff, bending back and forth several times does not result in it failing or work hardening to any extent i can ascertain from my
fingertips. A finely focused butane/air torch renders it shimmering red hot but induces no melting, boiled hcl to dryness it in and ended up with a
residual yellow spot of some sort of salt which went 'poof' into nothing when heated red hot, no pitting from this hcl treatment as i can tell. I
kinda like the thing and would rather not destroy it so anything more harsh i'm reluctant to unless it leads me somewhere.
thee constant heating/cooling has not affected its malleability as far as i can tell.
[Edited on 14-10-2008 by Panache]
[Edited on 14-10-2008 by Panache]Picric-A - 14-10-2008 at 07:21
Density test may work... If not melting point test.
If you dont mind loosing one a few simple acid/alkali tests should work... eg, try dissolve in, sulphuric, nitric, aqua regie ect...Vogelzang - 18-10-2008 at 12:22
I found the density of coins and pieces of silver by hanging them by a hair in an analytical balance and weighed them hanging from the hair alone and
then weighed them again while submerged in a cup of water. You can then calculate the density using Archimedes' principle.
[Edited on 18-10-2008 by Vogelzang]Panache - 19-10-2008 at 07:00
i did actually try this but i found the surface didn't wet thoroughly enough but even if it had my +/- 0.1g scales wouldn't really have helped. I do
really need to invest in some better ones i just have no regular use for them.\
Thanks for the input though
cheap specific gravity measurement
watson.fawkes - 19-10-2008 at 09:16
One of the reason that specific gravity is such an old measurement is that it doesn't need calibrated standards. What you do need is a set of
locally-consistent masses, that is, a set of counterweights in known small-integer ratios. Specific gravity is a ratio of two weights. You don't need
exact, absolute weights tied to international standards; you do need two measurements taken off the same set of weights.
All this is to say that you can pretty easily build a balance beam scale to measure specific gravity. A roll of coins makes a pretty good
mutually-consistent set of weights. Adjust the legs of the beam so that you're using enough coins to get an accurate reading. Measurement to 1% is
pretty easy with such a setup.Panache - 21-10-2008 at 19:08
Quote:
Originally posted by watson.fawkes
One of the reason that specific gravity is such an old measurement is that it doesn't need calibrated standards. What you do need is a set of
locally-consistent masses, that is, a set of counterweights in known small-integer ratios. Specific gravity is a ratio of two weights. You don't need
exact, absolute weights tied to international standards; you do need two measurements taken off the same set of weights.
All this is to say that you can pretty easily build a balance beam scale to measure specific gravity. A roll of coins makes a pretty good
mutually-consistent set of weights. Adjust the legs of the beam so that you're using enough coins to get an accurate reading. Measurement to 1% is
pretty easy with such a setup.
Of course, i have an old precise balance beam set of scales without counterweights however but i don't need them, now how do those spec gravity
equations work.....wiki...Panache - 21-12-2008 at 16:59
Quote:
Originally posted by Picric-A
Density test may work... If not melting point test.
If you dont mind loosing one a few simple acid/alkali tests should work... eg, try dissolve in, sulphuric, nitric, aqua regie ect...
Just thought i would tie-up the thread by informing a density test did indeed confirm the little suckers as Platinum, i ended up with a specific
gravity at RT of 21.5+/-.1, using 3 of the 5 boats which was good enough for me.
The method i used was weighing the boats on my +/-1mg counter balance, then sliding them down an almost filled burette and taking a before and after
reading. Sort of like using the burette as a measuring cylinder.
I didn't de-gas the boats but i can't see this as likely to affect things too much given the crudity of my method.
Once i had confirmed this i digested one of the boats at 50C in 15%HCl with a few grams of FeCl3 thrown in, for about and hour, there was no weight
loss.
Just a quick note though, the boat i digested i rinsed with water then brought it to red heat quickly to dry it, upon cooling it wasn't the typical
platinum dull silver rather kind of that oil on water in a puddle/mother of pearl style surface effect over the dull silver, with some areas of blue
over it. The blue i assume is some copper complex/salt from the platinum which usually has ~2% copper in it when it's used for foiling but the other
mother of pearl thing is unusual and quite pretty. It doesn't photograph very well.
