{HEAD ~ A second dividing wall} is disposed for {TAIL ~ the formation} of 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 the first and second dividing walls 
is disposed for
{ HEAD ~ A second dividing wall } is disposed for { TAIL ~ the formation } of 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 the first and second dividing walls
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