"Condensable non-aqueous ...wood tars ...[are] produced by pyrolysis and destructive distillation. Tars can be fractionated into [1] light oils, boiling below 200°C... [2] heavy tars, boiling above that... and [3] pitch. Light tars tend to be mixtures of aldehydes, carboxylic acids, esters, and ketones. Heavy oil contains... phenol derivatives; one of its uses... a wood preservative... wood tar creosote..."