does that ice thing work the same for aluminum?
To answer your question Jeff, this is a quick and dirty method that can be useful for determining what something is
not. You need to have two very similarly sized/shaped items placed in the same way on very similar shaped pieces of ice, and you need to be careful about handling them prior to doing the test (the less heat you transfer from your hands to the metal, the better). The degree to which this test is useful from a layman's perspective depends upon what you are trying to rule out -- in a lot of cases there are easier tests to do. For instance, it is very easy to tell if something is not made of steel, because steel has very, very low thermal conductivity. In your kitchen, things like aluminum, copper, and silver will all melt ice much faster than steel. It may be difficult to tell the difference between A) nickel, zinc, or tin, and b) steel or iron as they have less a difference in their thermal conductivity. A magnet may be more useful in some of those cases. Alloys of copper will lose a lot of the thermal conductivity of the copper, and so it can even be difficult to use this test to determine whether something is real brass or a base metal (again, magnet might be more useful).
This test could tell you: copper vs copper alloy; silver vs steel/iron/zinc/tin/nickel/others.
It will be more difficult to tell aluminum vs silver (weight is a better test), brass vs non-pure gold (i.e., jewelry). There are a lot of physics that go into this as I understand, and as soon as the temperature of the metal changes upon touching the ice, the conductivity will decrease. Most of the melting useful for this quick and dirty test happens in less than a minute. So there needs to be a big difference between the thermal conductivity of the metals in order to be able to spot a difference.
Hope all that makes sense. For what it's worth I'm not a scientist, this is just my understanding.
