The sixth plague of Egypt was ‘Shkhin’. The ‘Shkhin’ was a kind of skin disease, usually translated as “boils”. God commanded Moses and Aaron to each take two handfuls of soot from a furnace, which Moses sprinkled up toward heaven in Pharaoh’s presence. The soot induced festering ‘Shkhin’ eruptions on Egyptian men and livestock. In ancient Egypt, sores in the body were looked upon as punishment for sin, a means by which to call one to repentance.
http://andnowyouknowmore.blogspot.com