Ballyhoo, the test is not difficult but it does require attention to accuracy. You begin by weighing your raw coin and record that weight on paper. Then you fill a container with preferably distilled water and place it on the scale, then zero out the scale again. Then you attach a string to your coin and submerge in in the water making sure it doesn't touch the sides or bottom of the container. Then you record the wet weight of the coin and write it down on paper. The final calculation is in dividing the dry weight by the wet weight. 90% silver should be about 10.33 while copper is around 8.9. Gold is in the 17.2 range or higher. A good test to determine the composition of any suspect coin. As mentioned, my erroneous readings were coming from a miscalculation (I didn't factor in the weight of the string). So if you perform this test, check to see if your string has any weight in the water BEFORE you attach a coin to it.