OLD BOOK SMELL

Lignin is deprived from the Latin word lignum, meaning wood. Lignin is found in all vascular plants, mostly between the cells, but also within the cells, and in the cell walls. It makes vegetables firm and crunchy, and gives us what we call "fiber" in our food. It functions to regulate the transport of liquid in the living plant, and it enables trees to grow taller and compete for sunshine.

Due to lignin presence in paper, it yellows over time. 

Vanillin is the primary component of the extract of the vanilla bean. Synthetic vanillin, instead of natural vanilla extract, is sometimes used as a flavoring agent in foods, beverages, and pharmaceuticals. 


Making of synthetic vanillin was based on lignin wastes. Lignin-based artificial vanilla flavouring is alleged to have a richer flavour profile. 


And that is why books of yesterday smell of vanilla. 


'Lignin, the stuff that prevents all trees from adopting a weeping habit, is a polymer made up of units that are closely related to vanillin. When made into paper and stored for years, it breaks down and smells good. Which is how divine providence has arranged for secondhand bookstores to smell like good quality vanilla absolute, subliminallym stoking a hunger for knowledge in all of us'
Perfumes: the guide.