no_name writes:

(It's almost
like the old question about a pound of lead and a pound of feathers -
they do both weigh the same.)

However, a pound of gold and a pound of feathers do not.

Due to the archaic system of weights&measures that uses a different unit
with the same name for measuring precious metals.

But a gram of gold and a gram of feathers *are* the same mass, and have
the same weight in the same gravity.

Dave