The smell of old books could help preserve them

Old books give off a complex mélange of odors, ranging from pleasant (almonds, caramel and chocolate) to nasty (formaldehyde, old clothes and trash). Detecting early signs of paper degradation could help guide preservation efforts, but most techniques destroy the very paper historians want to save. Now, researchers have developed an electronic nose that can non-destructively sniff out odors emitted by books of different paper compositions, conditions and ages.