Using sulfuric acid??

I had another question of a different topic to ask. I bought a few rocks from a water garden nursery and they are labeled as river rocks. I read up on the need to use muriatic acid (sp?) but they only sold it by the gallon. I wanted to try something smaller and I found sulfuric acid at a pool supply store. My feeling is that both sulfuric and muriatic acid both have strong acid properites. Has anyone tried using this before? I went ahead and put a few drops on each of the rocks and nothing happened so I'm assuming the rocks are safe for aquarium use but I want to make sure by asking the experts here