Dissolving Old Concrete
 

I am a bonsai artist. Recently, I discovered a real treasure at an estate sale--a set of three bonsai pots. One of them had been filled with concrete and large pebbles to make it a heavy base for artificial trees. I want to remove the concrete. The pot is of fired clay with fired glaze. The inside, where the concrete sits, is not glazed. I'd rather not take a hammer and chisel to it. I read where muriatic acid could work if the concrete was not more than 28 days old; however this is definitely old concrete. Help, please!

The photo is an example of the kind of pot involved.

Noting will dissolve the concrete. Try drilling holes into it. Lots of holes and then you might be able to chip the concrete out.

Dissolving Old Concrete
 

Thanks for the answer, Joe--even though it wasn't what I'd hoped to hear. :(
It's the largest of the three pots with the concrete. The other two have been used the same way but seem to have a soft substance that will chip out fairly easily, so it's not a total loss.

I agree with Joe, whittling at it with a small carbide drill should loosen it up