This photograph! Discovered via @Baratunde and delighting me to no end. Some additional digging reveals that the woman is a performance artist, but she still chopped that onion on that train.
The science behind that beloved old book smell, as explained by a Richard from AbeBooks who pronounces "deterioration" in a pleasing way:
I am fully obsessed with Harmless Harvest's Coconut Water. Be warned: once you try it, you will find it difficult to enjoy other brands of bottled coconut water. This stuff smells (and tastes) so fresh and nutty and yummy; after I've finished drinking, I save the bottles until the smell is gone (always wearing eau de weirdo around here).