A puzzle.

I just thought of this. I don't have an answer, but I think I have an idea of how to get the answer.

Four people are sitting around a table. Each person has a liter of a different kind of soda in front of him. Taking turns and going clockwise, each person pours 100 milliliters of the liquid in front of him into the glass of the person to his left. How many times will they go around the circle like this until they all have the exact same mix of soda?

Okay, I have an answer now. If you want to cheat, I'll put it up on my old blog. If not, you can figure it out yourself. This is what I do at 3:30 am, when I'm trying to stay awake because I work the overnight shift tomorrow (technically, tonight).