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From: Steve Frank <taxi_steve929@yahoo.com>
Subject: Specific Gravity
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http://www.hauserandmiller.com/reference/melting.html
http://www.coincommunity.com/forum/topic.asp?TOPIC_ID=3D39666
The above sites seem useful to anyone performing specific gravity tests.=20
Recently I got together with a couple friends and we tested some coins for =
specific gravity. My concern is that these are alloys and the results were =
meaningless without knowing what the specific gravity should be on a genuin=
e coin. If a coin is supposed to be 90% silver and 10% base metal(s), the s=
pecific gravity will vary with the base metal(s) alloyed with the silver. R=
ecently I've been "playing around" with spanish silver coins, and wonder if=
any of the books detail either specific gravity or exact composition of ge=
nuine pieces so I can figure the specific gravity out myself.=20
What would the difference (percentage)=A0in specific gravity be between pur=
e silver and 90% silver alloyed with copper or brass or any combination? Sh=
ould I be that concerned with the alloy, or just do my calculations based o=
n 90% silver v. .999 silver?
I would really like to get into this a little more, and if someone here has=
already done a lot of work in this area, perhaps they could write up somet=
hing for C4 or CNLF so others who are not scientifically inclined don't hav=
e to plod through=A0their own mistakes to eventually re-invent the wheel.=20
I know that specific gravity should be a very useful tool in counterfeit de=
tection with these coins. (I see it used quite a bit in ancient coin counte=
rfeit detection)
I'm rambling and pressed for time as I just stopped home for a few minutes =
to type this....I hope there is some detailed analysis that has been done a=
nd that the method is incorporated into this analysis.
I also have some quesitons for Phil M about diminishing weights of St Patri=
cks coppers and the results obtained from testing grade v. weight loss of l=
incoln cents, large cents, and Mass copper coinage...I have a simple theory=
on why some coins lose more weight than others with wear that may have bee=
n looked at, but am waiting until I at least get through the entire chapter=
in the new COAC book...not a chapter you breeze through!!<s>
--0-960196047-1241101146=:58387
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<html><head><style type=3D"text/css"><!-- DIV {margin:0px;} --></style></he=
ad><body><div style=3D"font-family:times new roman, new york, times, serif;=
font-size:14pt;color:#000000;"><DIV><A href=3D"http://www.hauserandmiller.c=
om/reference/melting.html">http://www.hauserandmiller.com/reference/melting=
.html</A></DIV>
<DIV> </DIV>
<DIV><A href=3D"http://www.coincommunity.com/forum/topic.asp?TOPIC_ID=3D396=
66">http://www.coincommunity.com/forum/topic.asp?TOPIC_ID=3D39666</A></DIV>
<DIV> </DIV>
<DIV>The above sites seem useful to anyone performing specific gravity test=
s. </DIV>
<DIV> </DIV>
<DIV>Recently I got together with a couple friends and we tested some coins=
for specific gravity. My concern is that these are alloys and the results =
were meaningless without knowing what the specific gravity should be on a g=
enuine coin. If a coin is supposed to be 90% silver and 10% base metal(s), =
the specific gravity will vary with the base metal(s) alloyed with the silv=
er. Recently I've been "playing around" with spanish silver coins, and wond=
er if any of the books detail either specific gravity or exact composition =
of genuine pieces so I can figure the specific gravity out myself. </DIV>
<DIV> </DIV>
<DIV>What would the difference (percentage) in specific gravity be bet=
ween pure silver and 90% silver alloyed with copper or brass or any combina=
tion? Should I be that concerned with the alloy, or just do my calculations=
based on 90% silver v. .999 silver?</DIV>
<DIV> </DIV>
<DIV>I would really like to get into this a little more, and if someone her=
e has already done a lot of work in this area, perhaps they could write up =
something for C4 or CNLF so others who are not scientifically inclined don'=
t have to plod through their own mistakes to eventually re-invent the =
wheel. </DIV>
<DIV> </DIV>
<DIV>I know that specific gravity should be a very useful tool in counterfe=
it detection with these coins. (I see it used quite a bit in ancient coin c=
ounterfeit detection)</DIV>
<DIV> </DIV>
<DIV>I'm rambling and pressed for time as I just stopped home for a few min=
utes to type this....I hope there is some detailed analysis that has been d=
one and that the method is incorporated into this analysis.</DIV>
<DIV> </DIV>
<DIV>I also have some quesitons for Phil M about diminishing weights of St =
Patricks coppers and the results obtained from testing grade v. weight loss=
of lincoln cents, large cents, and Mass copper coinage...I have a simple t=
heory on why some coins lose more weight than others with wear that may hav=
e been looked at, but am waiting until I at least get through the entire ch=
apter in the new COAC book...not a chapter you breeze through!!<s></D=
IV></div></body></html>
--0-960196047-1241101146=:58387--
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