Sentence:  Nigh on the plain, in many cells prepared, / That underneath had veins of liquid fire / <WSD>Sluiced</WSD> from the lake, a second multitude / With wondrous art founded the massy ore, / Severing each kind, and scummed the bullion-dross. 
Meaning of the word marked with <WSD> tags:  To emit by, or as by, flood gates.