How to tell AP flour from self-rising flour?

Question

I have a tupperware container of all-purpose flour, and another of self-rising flour. Sadly, I did not label them, and now I've forgotten which is which.

Is there an easy way to tell them apart?

Answer 1

Take a little bit of each and add water. The self rising flour will look noticably different (bubbling etc) than the normal flour.