What is a good way for a laymen to purify alcohol to near 200 proof?
Distillation of ethanol yields 95% ethanol and 5% water. That is the best one can do unless you don't want to drink it afterwards (it will have a little benzene, a known carcinogen). The Epsom salts may remove some water, but I don't think it will remove all the water, not to mention that some of the Epson salt will dissolve into solution.