Sentence:  Technical terms like ferrite, <WSD>perlite</WSD>, graphite, and hardenite were bandied to and fro, and when Paget glibly brought out such a rare exotic as ferro-molybdenum, Benson forgot that he was a master ship-builder, […] 
Meaning of the word marked with <WSD> tags:  The lightweight insulating material and aggregate resulting from expanding perlite glass by heat.