Ever wondered why some books seem to self-destruct?

"Into Thin Air," Chapter 8 in

A SPLENDOR of LETTERS*, has a comprehensive explanation. "The transition to lesser-grade stock began around the time of the American Civil War (1860s), when increasing demand hastened the development of a cleaner process. To improve strength and to prevent ink from being too readily absorbed by the pulp paper, chemicals such as aluminum sulphate, known as alum, were added to the mix, with the result that documents exposed to humidity produced sulfuric acid, and the molecular structure of the cellulose was weakened. Further deterioration of the fibers was caused by bleaches that were used to brighten the sheets."

*Nicholas A. Basbanes, Perennial/HarperCollinsPublishers, 2003.