My definitions of billion and
potin are not the same. Clearly not everyone uses these terms the way I do, but my definitions are more useful. My definitions follow:
Billion is an
alloy of copper that contains less than half silver, usually much less than half, and its appearance is clearly not pure silver. For billion the silver the was an important consideration in determining the coin's value in circulation.
Potin is an
alloy of copper that contains, tin and/or lead in proportions great enough that the metal takes on a silvery, gray, or white appearance (often black when
toned). If
Potin contains silver it is incidental, unintentional, and is not a component in determining the coin's value in circulation.