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How does one test for silver content?

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  • joeengebretson
    Hi all- I m sure with all of the chemists here, someone will know this answer. How do I make a silver test kit? What chemicals and items do I need? Kits are
    Message 1 of 3 , Feb 2, 2006
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      Hi all-

      I'm sure with all of the chemists here, someone will know this
      answer.

      How do I make a silver test kit? What chemicals and items do I need?

      Kits are few and far between on ebay- so I was thinking about trying
      to make a test kit on my own- but I haven't the slightest idea of
      what I need.

      I've been buying Chinese sycee on ebay for silver bullion- but after
      doing more research, and asking some questions on a Chinese coin
      group- I'm pretty sure that I have forgeries. I'd like to test the
      sycee for silver content. As long as they are silver (even 25%
      content) I'm still alright investment wise for bullion. They look
      like silver and have the feel of aged silver... but now I have my
      doubts if they are even silver.

      Anyone have any ideas on testing items for silver?

      thanks
      joe
    • Robert Schneider
      Greetings Joe and All, One simple non destructive test would be to determine the specific gravity of your coin and see how close to silver it is. I just looked
      Message 2 of 3 , Feb 3, 2006
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        Greetings Joe and All,

        One simple non destructive test would be to determine the specific
        gravity of your coin and see how close to silver it is.

        I just looked up the specific gravity's of these 3 metals:
        Silver 10.5
        Tin 7.2
        Ni 8.9

        I believe that the definition of specific gravity is weight in grams
        divided by volume in cubic centimeters.  Getting the weight is easy,
        but you may have to buy a calibrated beaker to find the volume of
        the coin.

        By using algebra the following formulas can be derived:

        Assuming tin is mixed with the silver:

        Let: sg be the specific gravity of the coin
        then:
        Percent Silver = ((sg-7.2)/3.3)*100

        Assuming nickle is mixed with silver:
        then:
        Percent Silver = ((sg-8.9)/1.6)*100

        These tests aren't real exact because there will likely be more than
        1 metal mixed with the silver, but they are real easy to do and non
        destructive and they will give an indication if something is amiss.

        A second test is the streak test method.  This involves getting a
        piece of non-glazed porcelain and rubbing the side of the coin on it
        and noting the color of the streak.  The easiest place to find non-
        glazed porcelain is under the top the cover of the toilet tank.  I
        didn't look up the colors you should see, but if the streak is dark
        or black it probably means you have lead in the coin.  The streak
        test is the easy way to tell the difference between gold and fools
        gold (iron pyrite).

        Just a couple of simple ideas.

        Bob


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      • datrainn
        I remembered this post from Moneta_l back in Oct (#73357) from Scott Rottinghaus, that gives a method for testing for silver, that should be possible for most
        Message 3 of 3 , Feb 3, 2006
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          I remembered this post from Moneta_l back in Oct (#73357) from Scott
          Rottinghaus, that gives a method for testing for silver, that should
          be possible for most of us. Don't know if it works, but thought that
          I'd put it out there.
          Denny

          --- In Moneta-L@yahoogroups.com, "Scott Rottinghaus"
          <scottrottinghaus@...> wrote:

          Hi David and group,

          First of all, let me apologize for my careless the word "laziness" in my
          initial post--I have the utmost respect for you and your firm, and your
          e-mail below proves your care for this interesting coin. I think you
          will
          find in your office the equipment you need to check specific gravity with
          enough accuracy to confidently distinguish a silver coin from a
          subaeratus.
          Silver has a specific gravity of 10.5, and copper has a specific
          gravity of
          8.9. So all you really have to do is distinguish 10 from 9 to detect a
          subaeratus (we are not trying to be really specific about alloys, which
          requires much more careful methodology).

          Here is what I do. I use a balance that will weigh up to 200 g in 0.01 g
          increments. First weigh the coin and record the weight (using the
          example
          of a Republican denarius from my collection, 3.58 g). Next, put a small
          beaker (for that matter, you could probably use a Dixie cup)
          containing some
          distilled water onto the balance and zero it. Then tie your coin to
          the end
          of a thin piece of thread (this can be the difficult part--especially
          for a
          nice round coin like the Claudius denarius). Suspend the coin by the
          thread
          from a fixed point (a ring stand or a tripod works well--you can
          improvise)
          and submerge it entirely in the water, being careful to hold it still and
          not touch the edges or bottom of the beaker. Record the weight (0.34
          g in
          my example). This corresponds to the volume of water displaced (0.34
          mL of
          distilled water should weigh 0.34 g, which should also equal the
          volume of
          the coin, at 0.34 cc). Finally, take the weight of the coin divided
          by the
          weight of water it displaces, and you have the specific gravity
          (3.58/0.34=10.5). So the coin is silver.

          For such a small coin, I really only have two significant figures
          (0.34), so
          I can really only say with confidence that the specific gravity is
          about 11.
          Still, that is good enough to say that my coin is silver and not
          copper.
          And I can figure that out in less time than it took to write this e-mail.

          Thanks again for your careful description of the coin!

          Scott


          >From: david michaels <flaviuscrispus@...>
          >To: Scott Rottinghaus <scottrottinghaus@...>, pdimarzio@...,
          >Moneta-L@yahoogroups.com
          >Subject: RE: [Moneta-L] Claudius DE BRITANNI den
          >Date: Mon, 10 Oct 2005 17:16:35 -0700 (PDT)
          >
          >Dear Mr. Rottinghaus et al:
          >
          >The coin in question, lot 536 from our Mail Bid Sale
          >12, can be viewed here:
          >
          >http://www.freemanandsear.com/mailbid.php?cmd=viewLot&lotID=10124
          >
          >(Click on the image for a larger photo)
          >
          >I've examined the coin under a microscope, and whole
          >there are signs of surface cracking and "delamination"
          >(i.e. the metal separating into layers), there is no
          >sign of a copper core showing through. There is a
          >fairly deep scrape or "divot" in the field to the
          >right of the portrait, but there is no sign of copper
          >base metal in this mark.
          >
          >As you noted, the coin is rather heavy for a fourree,
          >and in fact is about the same weight you'd expect for
          >a regular issue Claudian denarius. However, given the
          >other signs (and the fact that the principal author in
          >the field regards all types with a DE BRITANNI reverse
          >to be irregular), I still highly suspect the coin to
          >be plated. We just can't find any definitive proof of
          >of a base metal core, hence the question mark.
          >
          >I am under the impression that, in order to do a
          >specific gravity test on something the size of a coin,
          >you need to immerse the piece in some kind of liquid
          >and be able to measure the displacement very
          >precisely, which requires a pretty sophisticated piece
          >of measuring gear. Is there some other way to
          >non-destructively measure the SG?
          >
          >David S. Michaels
          >Sales Director
          >Freeman & Sear
          >
          >
          >
          >--- Scott Rottinghaus <scottrottinghaus@...>
          >wrote:
          >
          > > Hi Paul,
          > >
          > > "Irregular" is usually a code word for "unofficial,"
          > > suggesting either a
          > > contemporary imitative issue or a contemporary
          > > counterfeit.
          > >
          > > It can indeed be determined definitively and by
          > > completely non-destructive
          > > means if a coin is plated, and it frustrates me when
          > > auction houses of the
          > > high quality of Freeman & Sear list coins as
          > > "fourre(?)." The coin may have
          > > a bit of core exposure in the obverse field in front
          > > of the portrait--this
          > > is not clear to me from the picture. The weight is
          > > heavy for a plated
          > > denarius of Claudius. Somebody needs to check the
          > > specific gravity--that
          > > would give the answer. It's laziness not to do so.
          > >
          > > Scott
          > >
          > >
          > > >From: "pdimarzio" <pdimarzio@...>
          > > >To: <Moneta-L@yahoogroups.com>
          > > >Subject: [Moneta-L] Claudius DE BRITANNI den
          > > >Date: Fri, 7 Oct 2005 08:39:00 -0400
          > > >
          > > >Hi!
          > > >
          > > >The current Freeman & Sear mail bid sale lists as
          > > lot 536 a "fourr,e(?)"
          > > >[sic] denarius of Claudius with the reverse
          > > inscription DE BRITANNI.
          > > >Here's
          > > >a link:
          > > >
          > > >http://tinyurl.com/ctslk
          > > >
          > > >The description notes that "According to Kaenel,
          > > all coins of Claudius with
          > > >DE BRITANNI instead of DE BRITANN are irregular
          > > issues. He did not record
          > > >any irregular examples dated TR P VIIII IMP XVI,
          > > but for the others, see p.
          > > >108, 231-233." There is also a reference to "Von
          > > Kaenel p. 86, Type 31".
          > > >
          > > >I have two questions that I hope the listmembers
          > > may be able to answer for
          > > >me, since I don't have access to the cited
          > > reference.
          > > >
          > > >1) What does "irregular issue" mean? Does this
          > > mean contemporary
          > > >counterfeit, official emergency issue, or is there
          > > some other theory?
          > > >2) Why would it be listed as a fourree with a
          > > question mark? I thought
          > > >that
          > > >fourrees were plated coins, wouldn't this be
          > > something that could be
          > > >determined definitively? (I've never handled one
          > > so I really don't know).
          > > >
          > > >Thanks!
          > > >
          > > >Paul DiMarzio
          > >
          > >
          > >
          > >
          > > Your moderators are:
          > > Kevin Barry (http://www.bitsofhistory.com)
          > > Thom Bray (http://www.romancoin.com)
          > > Dave Garstang
          > >
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          > >
          > >
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