A second dividing wall is disposed for the formation of an underside glass passage, and {HEAD ~ at least one closable opening} for withdrawing {TAIL ~ the molten sulfates} is disposed at the level of the sulfate layer between the first and second dividing walls 
for withdrawing
A second dividing wall is disposed for the formation of an underside glass passage , and { HEAD ~ at least one closable opening } for withdrawing { TAIL ~ the molten sulfates } is disposed at the level of the sulfate layer between the first and second dividing walls
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH