How to tell if flour is self-rising

Toast
My mother recently gave me a bag of self-rising flour she accidently bought.  I thought I had labeled the container, but didn't.  Is there a method to tell whether flour is self-rising or regular?  I hate to waste it or other ingredients experimenting.  Thanks.

Two ways come to mind. Since self-rising flour contains baking soda, try adding some vinegar and see if it bubbles. Also, the next time you have a hot pan, take about a teaspoon of the flour, add some water and make a small pancake. Toss it in the pan, and if it rises, it's self-rising flour.