What Causes Wood Exposed to Dampness to Rot Away?
There are kinds of wood that will not rot away, even though they are kept in water. The city of Venice is built on wooden piles buried in the shallow sea, and these have lasted for many centuries.
We shall guess what it is that makes wood rot when we learn what is done to protect wood that must be exposed to wet, for instance, the wood of which railway ties are made. These are often soaked with a chemical substance called creosote; and the particular property of creosote which makes it so valuable is that it is poisonous to microbes. So the answer to the question, in one word, is: Microbes. Wood will not rot if it is charged with something that kills microbes, or if, as in the case of Venice, it is protected from microbe enemies by being kept in salt water.
If you live in the southern United States, or have visited there, you have seen swamps with bald cypress trees growing in them. Cypress wood is remarkably hard and resists attacks of insects and microbes. The wood of the bald cypress, which grows in the swamps, is used for railway ties, fence posts, telegraph poles, piles for docks and other purposes for which a water-resistant wood is needed. From pine wood, which contains much creosote, we get wood tar that is applied to other woods to protect them.
