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<p>[QUOTE=&quot;funnycoins, post: 3612779, member: 103887&quot;][ATTACH]967547[/ATTACH] Following <a href="https://www.nytimes.com/1981/08/29/business/zinc-penny-ruling-is-expected-soon.html" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://www.nytimes.com/1981/08/29/business/zinc-penny-ruling-is-expected-soon.html" rel="nofollow">debates in Congress in 1981</a>, the decision was made to change the composition of the penny from 95% copper and 5% zinc to 97.5% zinc and 2.5% copper in 1982. More precisely, the new pennies would be made from a nearly pure (99.2%) zinc core with an outer layer of pure copper. Production of the new zinc pennies was phased in throughout 1982, and by 1983 (except the 1983D) all pennies were supposed to be made from the new composition. So I have 5 of these un-plated, re-plated cents from the d mint that weigh 3.1 or 2.5 each. Start with a weight of 2.5 grams total for a copper plated zinc cent, then take the official composition of 97.5% zinc, 2.5% copper and figure from there? All of that 2.5% copper is plating, so 2.5 grams times 2.5% equals 0.0625 grams of copper plating per cent. How did the silver weight (clad?) come out so precise? Also with the 1982D thats a tight tolerance to follow. These were tested using conductivity testing. Results were &quot;silver no copper&quot;. Could a homemade specific gravity test help me debunk this oddity? </p><p><font size="5"><b>The Specific Gravity Test</b></font></p><p>These next 4 tests are highly accurate in determining real vs. fake. The specific gravity test of silver is basically a ratio of densities and due to its chemical &amp; composition makeup should equal ~ 10.49, given by the formula below:</p><p><img src="http://www.silvercoins.com/wp-content/uploads/2014/07/specific-gravity-silver.png" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /> </p><p>This test will weed out those silver-plated or clad coins if they have a composition of some other base metal. You cannot change the density of metal and pure silver will always give a reading close to 10.49. To calculate this perform the steps below:</p><p><br /></p><ol> <li>Obtain dry weight of the silver coin or bar with an accurate scale to .01g</li> <li>Use a cup of water enough to fully submerge the silver into and measure its weight or reset the scale with it on.</li> <li>Tie some string around the coin and setup an apparatus to hold the coin</li> <li>Submerge the silver into the water and record the submerged weight minus the weight of the water &amp; cup.</li> <li>Divide the dry weight by the submerged weight to obtain the specific gravity of silver</li> </ol><p>[ATTACH=full]967546[/ATTACH] [ATTACH]967535[/ATTACH] [ATTACH]967536[/ATTACH] [ATTACH]967538[/ATTACH] [ATTACH]967539[/ATTACH] [ATTACH]967540[/ATTACH] [ATTACH]967542[/ATTACH] [ATTACH]967544[/ATTACH] [ATTACH]967545[/ATTACH] [ATTACH]967546[/ATTACH] [ATTACH]967547[/ATTACH] [ATTACH=full]967547[/ATTACH][/QUOTE]</p><p><br /></p>

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