How do you make acid from a rose petal?

I and my scientific research group, discovered that we must extract the rose petal first, to gain the acid. We could extract it with boiling the rose petals with a few mililiters of water in a beaker glass. Try to extract it with spirtus and tripod, so that the extract will be pure and got the maximum quality.

After we extract it, we could test it with the litmus paper.

I'm sorry if the answer didn't fulfill your need.

And sorry for the fail Engish.