Sentence:  I have ſeen Turf <WSD>chark</WSD>'d, and then it ſerves to work Iron, and, as I have been inform'd will ſerve to make it in a Bloomery or Iron-work. Turf <WSD>chark</WSD>'d I reckon the ſweeteſt and wholeſomeſt Fire that can be, fitter for a Chamber and conſumptive People, than either Wood, Stone-Coal or Charcoal. 
Meaning of the word marked with <WSD> tags:  To reduce by strong heat, as to produce charcoal or coke; to calcine.