A park visitor emailed us this question today: Hi, I was walking in the woods behind my house in Fairfield, Vermont today and I noticed white foam on a number of our trees especially most of the yellow birch and also some hemlock. On some of the trees there was quite a bit of this foam. Is this something that we should be concerned about? I don't remember ever noticing it before. Thank you for your help. Rebecca Phelps, our Conservation Coordinator, replies: You are very observant, and what you were observing was Chemistry in action! What you saw on the trunks of these trees was the formation of a crude soap. It has been really dry for awhile in Vermont, and when it is dry particles from the air deposit themselves on the surface of tree bark (like dust). This dust includes bits of salts, acids and other particles in the air. When it rains, these particles dissolve into a liquid solution. Soap is essentially a chemical mixture of salts and acids formed into a molecule, and tha...
