Whereby that which is in their bellies will be melted and their skins too.
It will cause their insides to melt, as well as their skins.
and that which is in their bellies and their skins shall be melted
With it will be melted what is in their bellies and (their) skins as well
What is in their bellies/insides and the skins is being melted/anointed with it
The water will be so hot that not only it will burn their skins but also penetrate and melt inside them
With which will melt what is in their bellies, and their skins
Whereby that which is in their bellies, and their skins too, will be melted
With it will melt whatever is in their bellies and also (their) skins
Whereby whatever is in their bellies will be melted, and (their) skins as well (will come off their bones)
With it will melt or vanish away what is within their bellies, as well as (their) skins