I didn't see any obvious past threads on this, so thought I'd ask. What's the best way to test the specific gravity of a coin? (assuming we're talking unslabbed coins here) An internet search showed up a few methods of suspending the coin in water and weighing in and out and running the numbers. I suppose I'm primarily curious if people here test any of their coins this way, and if so, how you do it, or if you have any advice for a beginner. Thanks!
Hope for Eureka, again! I truly hope someone here resolves this. There must be a noninvasive technique to get SG. I mean, wasn't Arkamedes 1st challenged to determine SG quite some time ago? http://answers.yahoo.com/question/index?qid=20090223130047AAsGw8p I kinnda like this simple approach but you still have to "dip" the victim AND have a really good scale AND a perfect other example.
Welcome to the forum. Determining specific gravity requires that one has the weight of the sample as well as the volume. The weight can be determined easily, the volume of a sample with uneven surfaces something else. So for volume, usually a water displacement is used. The volume of water displaced can be measured by accurate syringes, or by weight of the water. The most common way is to use the weight of the object out of water compared to the weight of the object under water. Here is a url for a relatively inexpensive SG kit. http://www.mineralab.com/Specific%20Gravity.htm When I do sp. gr. I use a modified Mettler balance with a 2 tier pan, the lower tier below water level. I get dry weight by measuring the weight in the upper tier of the pan( above water) and then transfer the object to the lower part of the pan under water for the second weight. It is overkill for coins that are very large compared to gemstones, but it still works when I need it. Jim
Hey. That sounds useful. A totally useless method I used to use involved a column and nasty chemicals and thousands $'s in scales and volumnmetric flasks.
