New Hampshire Underground

New Hampshire Underground => Underground Projects => Topic started by: Eli on January 11, 2008, 08:36 AM NHFT

Title: Simple way to measure the purity of silver?
Post by: Eli on January 11, 2008, 08:36 AM NHFT
It seems to me, from my now distant chemistry classes,  that it should be fairly simple to determine that a one ounce coin is .999 silver.

Seems one could figure out (I haven't yet) how much water one once (or any other quantity) of silver should displace.  This would make picking out good coins from fakes as simple as wieghing a coin and then dropping it in a measuring cup of water.

Am I missing something or is it really that simple?

I submit this idea to the general wisdom for criticism.


PS I was a C chemistry student.

Title: Re: Simple way to measure the purity of silver?
Post by: malcolm on January 11, 2008, 09:03 AM NHFT
That is an old issue with silver as money.  All elements heavier than gold are also more expensive than gold, so this test works for gold purity (from a monetary, if not chemical standpoint).

The same cannot be said of silver, however.  An alloy of (let's say) tungsten and zinc might have the same density and visual appearance of silver, but not be silver.
Title: Re: Simple way to measure the purity of silver?
Post by: dalebert on January 11, 2008, 09:41 AM NHFT
Silver has a familiar ring to it when it clinks against other silver. That alone prolly makes it far less of a counterfeit threat than FRNs. People hardly glance at those when they take them, at least in units of about $20 or less.
Title: Re: Simple way to measure the purity of silver?
Post by: JonM on January 11, 2008, 01:15 PM NHFT
Silver in .999 form should have a fairly specific electrical resistence that an alloyed metal may not be able to match.  I suspect if you could build an affordable device that could actually do this well without damaging the coin you'd be rich
Title: Re: Simple way to measure the purity of silver?
Post by: John Edward Mercier on January 11, 2008, 03:22 PM NHFT
Quote from: dalebert on January 11, 2008, 09:41 AM NHFT
Silver has a familiar ring to it when it clinks against other silver. That alone prolly makes it far less of a counterfeit threat than FRNs. People hardly glance at those when they take them, at least in units of about $20 or less.


Anything considered of value will sooner or later be counterfeited.
Title: Re: Simple way to measure the purity of silver?
Post by: ancapagency on January 11, 2008, 03:47 PM NHFT
Quote from: Jon Maltz on January 11, 2008, 01:15 PM NHFT
Silver in .999 form should have a fairly specific electrical resistence that an alloyed metal may not be able to match.  I suspect if you could build an affordable device that could actually do this well without damaging the coin you'd be rich

The problem w/ electrical resistance tests is that electrons only travel on the outside--thus a plated coin would test identical to a solid pure coin.
Title: Re: Simple way to measure the purity of silver?
Post by: BaRbArIaN on January 11, 2008, 04:17 PM NHFT
There is no *simple* way to gauge purity.  The complex ways vary from x-ray fluorescence, chemical reactions and spectrographic analysis.   If you can heat it up in a flame or shine a very white light on it (even intensity distribution along the whole visual spectrum), you might be able to identify the associated metals it contained (silver has an absorption line at 328.1 nm, copper and aluminum have their own lines which you could verify).

For actual numbers for purity you might have to use the x-ray method (certain peaks have different magnitudes dependent on the number of atoms present).
Title: Re: Simple way to measure the purity of silver?
Post by: dalebert on January 11, 2008, 06:58 PM NHFT
Quote from: John Edward Mercier on January 11, 2008, 03:22 PM NHFT
Anything considered of value will sooner or later be counterfeited.

Just saying it's harder to counterfeit than FRNs and that people don't worry much about that. I don't think it makes much sense to do complex testing unless you're talking about a large exchange. It's just a matter of doing a little risk/benefit analysis.
Title: Re: Simple way to measure the purity of silver?
Post by: John Edward Mercier on January 11, 2008, 07:46 PM NHFT
The paper dollars are continually optically scanned at the banks.
Counterfeits hurt the solvency of a system by making it suspect.

And wouldn't the holdings in precious metals of the masses need to increase significantly for the system to replace the current one?

Title: Re: Simple way to measure the purity of silver?
Post by: BaRbArIaN on January 15, 2008, 12:28 PM NHFT
If you at least want to verify that a coin is made mostly of some metal, you could just plug in the diameter and thickness to get a volume and weigh it on a digital scale.  If its density is what you are looking for within a couple percent or so you might be reasonably certain of its purity unless someone does something complicated like coat tungsten slugs with lead and a fine gold layer to balance out to weigh the right amount.  Not worth the trouble for the most part, since once the deception is known, the deceiver's reputation would fall harder than the legitimacy of the Federal Reserve.    That's why I like the x-ray burst method, you get metal peaks and can identify elements in the target.   Might be hard to make one handheld and cheap tho.
Title: Re: Simple way to measure the purity of silver?
Post by: Eli on January 15, 2008, 12:40 PM NHFT
I was thinking less handheld and more vendor countertop.
Title: Re: Simple way to measure the purity of silver?
Post by: J’raxis 270145 on January 15, 2008, 02:47 PM NHFT
Historically, it was more common for people to "cheat" with silver currency, not by counterfeiting it, but by shaving minute amounts of silver off the coin, usually along the edges. Do it to enough coins and you have enough silver to melt down and make a new coin. It's probably more important to guard against this than outright counterfeits.
Title: Re: Simple way to measure the purity of silver?
Post by: Eli on January 15, 2008, 03:02 PM NHFT
really accurate scales are a good deal cheaper than they were historically.
Title: Re: Simple way to measure the purity of silver?
Post by: sandm000 on January 15, 2008, 03:23 PM NHFT
Didn't Ron Helwig post some sort of balance where it only tips if it's a gold coin? You run it through a slot, confirming its volume, then put it on the scale confirming its weight.  Weight/volume = density and this method would be hard to fake.

And as J'raxis has said shaving is more of a problem with silver, if you had these scales for silver you wouldn't need to worry about that, only the shaver would ever have his money rejected.  Although I could see a coin wearing down enough to lose some weight and be rejected, and the niche purchaser would be the Jeweler, you have a piece of silver no one else will take, he'll probably take it off your hands at 90% of face value, or something like that.

Also with modern technology, lasers could measure the object and you could weigh it and you could know instantly (or nearly so) what it was.
Title: Re: Simple way to measure the purity of silver?
Post by: Eli on January 15, 2008, 03:39 PM NHFT
Of course this could hardly be worse than inflation.

That is what I've come to realize.  I didn't like the lib dollar at first because it was being called dollars but weren't worth the dollar amount impressed upon them.  But the were worth more than those paper dollars (at least intrinsically).

If enough people will accept coins at the MSRP then they would be better than FRNs in every way.
Title: Re: Simple way to measure the purity of silver?
Post by: dalebert on January 15, 2008, 07:01 PM NHFT
That's a point that wasn't lost on me, Eli. The liberty dollars are definitely way marked up, but look at the $10 ones. The face value used to be a huge markup and now it's WAY below market value. I still believe liberty dollars are a scam but what does that say about FIAT money? However much of a scam liberty dollars are, it just shows that federal FIAT money is MUCH worse of a scam.
Title: Re: Simple way to measure the purity of silver?
Post by: cigarlover on January 15, 2008, 07:07 PM NHFT
Why not just give the silver coins a specific weight like the minted gold coins? 1/10th 1/4 1/2 1 oz.

I'm not sure what your intentions are but if it is to use in place of frn's then people will start to follow spot price and price the coins accordingly on any given day. The drawback of course is a spike up or down in spot during the day but I think this becomes an issue even if you place a numbered value on the coin. The liberty 20.00 coin for example. What happens when spot rises to 25.00? I would think you then revert back to using the spot price during transactions. Anyway, just hgrowing some thoughts out there. I do buy gold and silver every week when I get paid. Cant stand the FRN's and theres nothing better than holding a stack of silver coins :)
Title: Re: Simple way to measure the purity of silver?
Post by: Lloyd Danforth on January 16, 2008, 07:32 AM NHFT
Clinkidy...clinidy..clink! I always have some silver in my watch pocket. Along with a few .oz coins I carry two $5 LD's. The older one is 1/2 oz. and a newer 1/4 oz.  I use them as an object example of the falling value of the dollar.
When I am around friends as old as I pull 3 or 4 pieces of silver out of my pocket, clink it in their ear and say, "Remember that sound?" ;D
Title: Re: Simple way to measure the purity of silver?
Post by: Ron Helwig on January 16, 2008, 09:15 AM NHFT
Quote from: cigarlover on January 15, 2008, 07:07 PM NHFT
The drawback of course is a spike up or down in spot during the day but I think this becomes an issue even if you place a numbered value on the coin.

That's why I was thinking of trying to use something like the 30 day moving average.

We could post the suggested trade price on the Shire Silver (http://shiresilver.com) site. Maybe just update it on Sundays or something.
Title: Re: Simple way to measure the purity of silver?
Post by: Eli on January 17, 2008, 10:06 AM NHFT
If I were a merchant I might use the simple expedient of previous days close + the minting premium.  This should be easy to program into a POS and to post for customers.