What kind of acid will dissolve a tree stump?

Answer 1

Drill holes in it and fill them with potassium nitrate soak it in and let it stay for a few months it will rot out. If you don't want to mess with potassium nitrate get a jar of stump remover, it's potassium nitrate.

As with the above answer, drill one long hole into the top of the stump. Use a long auger bit and make it the diameter to fit a good sized funnel.

Pour kerosene (paraffin) into the funnel until its full. Check the level from time to time and top up as necessary.

Once the stump and a good part of the roots system are thoroughly saturated, ignite the stump with a blow torch. It won't go up in flames, just smoulder away until the whole thing is turned to ash.

If both of these two ideas seem a bit too long winded for you, then you need the services of a stump grinding company. Using a mechanical, abrasive system, they will grind the stump down, below ground level, in short order.