To try and debride the necrotic black leathery skin, warm soaking in pretty much anything for 20 mnutes or so daily will work. Use a little friction with a cloth to remove the skin. If you see bleeding, that is enough. Hydrogen peroxide is also excellent for debriding used full strength, but don't use it once the skin is pink and more normal looking since it can prevent healing. Coat the wound with antibiotic ointment afterward, such as plain Triple Atibiotic or Neosporin.