# platinum crucible



## pinman (Feb 17, 2009)

I came across what i think is a platinum crucible at a thrift store recently. 
would it be soft? its a large cup maybe 4" across the top holds maybe 6oz of water. its got acid markings on the inside and it is apparent its not plated. i can squeeze the mouth of it and it bends. any ideas?


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## Harold_V (Feb 18, 2009)

Platinum crucibles are, indeed, soft. Very soft. They are also very heavy. Platinum weighs roughly 10% more than gold. 

Some I've seen are marked with their content. They can be alloys of platinum group metals, not necessarily pure platinum. 

Size concerns me. All of the platinum equipment I've seen (not very much) was small, no larger than a couple inches in diameter, tops, and about that tall. That doesn't mean there may not be larger items made----but the price would be staggering. 

A simple test for platinum is heating. It should withstand being heated beyond redness, and remain bright when cooled. If it discolors, or melts, you can rest assured it is not platinum. 

Picture?

Harold

edit: corrected spelling of weighs


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## pinman (Feb 18, 2009)

thanks for the quick reply, i will get a torch and try that. the only picture option i have is my phone camera which is horrible quality because there is dust under the plastic. i will get a picture asap btw is weighs 71 grams if that is of any help


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## Harold_V (Feb 18, 2009)

pinman said:


> thanks for the quick reply, i will get a torch and try that. the only picture option i have is my phone camera which is horrible quality because there is dust under the plastic. i will get a picture asap btw is weighs 71 grams if that is of any help


That doesn't help much, all depends on wall thickness. All of the platinum ware I've handled was easy to deform. 
If you heat it, and it's platinum, it will melt at a dazzling white temperature---so high that you get radiation burns (what---UV exposure? Certainly not atomic radiation). 

If it starts to melt while it's still in the yellow range, or below, for sure it's not platinum. 

If it's very white, similar to silver, it may be just aluminum. Are you familiar with its appearance? Having worked as a machinist, it's easy for me to distinguish from other metals. That may not be true for everyone. That's why I ask----not implying you're a dope! 

A second thought. If the color leans towards a very light yellow (think 300 series stainles steel), it might be nickel. 

Harold


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## pinman (Feb 18, 2009)

man i love how fast you reply!
its a metal im not familiar with, positive its not stainless, aluminum, silver, or pewter. its a very shiny white with spots that have been dulled by whatever left the etching on it.


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## pinman (Feb 18, 2009)

im getting kind of excited, i used an acid test kit, i scratched the bottom of the dish on the stone and it didnt dissolve in the acid labeled platinum. it was a small bottle with a black cap that said it contained muriatic and nitric acids. i need a torch! the wall of the dish is about as thick as 7 sheets of printer paper. here is a picture from my phone, the soda can is for scale.


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## pinman (Feb 18, 2009)

sorry for the poor quality picture, the first picture is for scale, the second was to try to show you the acid marks inside, as i said before its apparent its not plated. and its very soft.


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## jimdoc (Feb 18, 2009)

It looks to be a little thick to be platinum to me.
Alot of labware is just platinum plated. The stuff
I have seen bends very easily. I actually found
a crucible in the trash years ago and threw it back
because it was so thin and beatup, and I didn't know
what it was back then. 
Jim


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## goldsilverpro (Feb 18, 2009)

You might be able to rig up your scale so you can weigh it in water and then compute the density. A torch would be best, though.

I've never heard of a platinum plated crucible but that doesn't mean they don't exist. It seems that Google hasn't heard of them either.


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## pinman (Feb 18, 2009)

like put my scale in a plastic baggie and put it in water?


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## pinman (Feb 18, 2009)

pretty positive its not plated from the scars left by the acids.


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## pinman (Feb 18, 2009)

are there any other metals that are this malleable and color that could resist the acid in the test vial?


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## goldsilverpro (Feb 18, 2009)

> like put my scale in a plastic baggie and put it in water?



NO! The object *ONLY* must be somehow suspended from the scale, submerged in distilled water, and weighed while in the water. What kind of scale do you have? Is it a standard small flat digital scale? What is the maximum capacity? What is the smallest amount that can be weighed - .1gm, .01gm, .001gm? Can you take a photo of the scale?


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## lazersteve (Feb 18, 2009)

Pin,

If it were me I would shave a small sample of the edge of the dish off using a razor knife or sharp clippers.

This tiny sample would go in a test tube with several drops of HCl and a few drops of HNO3. Now apply heat until the liquid boils. Test a drop of the solution with stannous chloride to determine if PT is indeed present.

This test can be performed in a matter of minutes and will the prove the presence Pt or not.

Steve


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## Harold_V (Feb 19, 2009)

Steve's suggestion is very good---but be advised that if it is platinum (the color is killer good I'm thinking it could be), it will not dissolve readily. You may have to heat for several minutes before you see any color drift of the solution. Pray that be the case, for if it is, it's likely platinum. If you get a fast reaction and the color is dark, it won't be platinum, but it could still have value, and likely does. 

Do you have stannous chloride? If so, do you understand the color reaction for platinum and palladium? 

Steve is likely the best equipped to guide you in that department if you have any doubts. He has almost all of that information readily available. 

By the way, that's an evaporating dish----so that it might be platinum makes perfect sense. 

Good luck!

Harold


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## Lou (Feb 19, 2009)

It looks like the ones I use 

The dirty inside makes me suspicious. It shouldn't have that appearance. Well worn platinumware has a matte finish with an almost sandy grain texture to be observed. This is because it has been heated oh so many times.


Most crucibles/evap dishes these days are clad unfortunately, but yours might be quite old.


You can send it to me for identification and permanent safe-keeping, such a thing is useful!

My advice to you: obtain some sort of torch, heat to yellow hot in an oxidizing flame and let it cool to room temperature. You should see no discoloration. That is the best test for platinum labware. If that tests positive, you should proceed to get a density on it. 

*You should not file out a notch or snip a piece out of it. Often, these platinumware pieces are worth more than their weight in platinum, usually about 15-20% in spot if they are in good condition.*


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## pinman (Feb 21, 2009)

you guys are a lot of help!
i have a small digital scale that weighs up to 230 grams or so.
I dont have any chemicals what so ever except for my small test kit.
im going to buy a torch after work today i am really anxious to find out what it is!
if this turns out to be platinum, word to the wise... look around the stainless steel thermos's, the lady thought it was a cap to an old thermos sold it to me for .25 usd


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## pinman (Feb 21, 2009)

so going off of what you guys told me im pretty sure its platinum.

i got it red hot and it cooled back down to the white color.

any suggestions as to where i can sell this and not be ripped off?


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## pinman (Feb 21, 2009)

the black stuff in the bottom glowed green when i had the torch on it, when it cooled it actually seemed cleaner than before the heat


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## jimdoc (Feb 21, 2009)

I would check with Lou or Steve, you know they will be honest
with you. Also, that was an awesome .25 cent find. You should
check back at that place and ask if they have any more, they 
may even have thrown out some beatup ones. If they got that
one, there is always a chance there are more that came in with
that one. Jim


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## pinman (Feb 21, 2009)

oh i went straight back for sure! there wasnt anymore near the thermos' and the woman didnt recall the piece i showed her. but there was alot of lab glass. so i bought a couple of small pieces for possible experiments in the future. thanks again for all the help.


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## Lou (Feb 23, 2009)

Chances are someone she knew was a chemist and she some how got a hold of their equipment.


As far as a density test goes, I suggest you read back earlier, several people have mentioned how to do it.


Ebay or labx might be a good choice for the dish.


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