Dead tissue would normally start be become dry and discoloured; due to the many different types of chemicals, I would recommend visiting your Veterinarian to have a look at the
burn and to determine whether it is acid or
alkali as well as pH etc... and to start treatment.
We also need to take into account coal -
burning power plants, mining, waste incinerators, hospital crematoria, cement factories, thimerosol, chemical plants, fungicides, chlor -
alkali plants, mercury amalgams, switches, gauges, CFLs, and of all things, shipwrecks contributing mercury pollution to our planet.