Now, this is where oxidation of potassium takes place. And this is where reduction of potassium takes place. You could think of this conductor, that electrodes and a sulfbridge, as representing the cell membrane. And the solution on this in this anode is the outside solution and the cathode is the inside solution. And that's because initially in a concentration cell, this guy is more dilute. That means it's the outside, because remember, we have less potassium on the outside than on the inside.