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