[Wil"]

I'm really confused by the words describing "salt bridge" in the book, hope someone can clarify this for me.

Suppose we Soln A(Zinc sulphate) and Soln B(Copper II sulphate). The salt bridge contains NaCl.

The book describe "salt bridge" as "it completes the circuit by allowing ions to move between the two half-cells"

So I want to ask what the the "ions" the sentences refer to??
the NaCl to the two soln;
or Mg2+ soln to Cu2+ soln through the salt bridge??

[agrobert]

http://en.wikipedia.org/wiki/Salt_bridge