With 300 detectable chemical compounds, the liquor is more complex than human blood:
Tannin, which makes tea brown, gives whisky its golden glow. Oak lactones also mingle in, giving a hint of sweet coconut. The carbon lining of charred whisky helps to release vanillin from the oak. The active carbon filters out undesirable substances like sulphur that cause an eggy taste. Gaps and pores in the cask’s wood let in air. Gently, gently, this air oxidises the alcohols, breathing new life into the spirit.