Floating Gold: A Natural (and Unnatural) History of Ambergris, by Christopher Kemp. Rich, sexy, earthy and enticing: this precious ingredient is prized by perfumers, yet can’t be ‘harvested’: it’s simply washed up randomly on beaches, being a by-product of the whale’s digestive process. (Not so long ago, a stroller on a Dorset beach found a lump of ambergris, alleged to be worth up to £80,000.) Christopher Kemp has woven a fascinating tale around a single fragrance element, bringing to life ambergris’s place in fragrance history and creation. A book to make beachcombers of all of us.