http://www.ehow.com/way_5720752_epsom-salt-formula-stump-removal.html I goggled your answer. However, I have always used the method of cutting a grid in the tree stump after cutting it as low as possible or driving an extremely cheap screwdriver into the heart of th stump.
What I saw was that you have to drill a few holes in the top of the tree stump and pour the epsom salt right into the holes. Good luck!
Thank you both ... we worked on the stumps today.