The Fourth of July is just days away, and that means millions of Americans will soon enjoy eye-popping fireworks displays around the country. These dazzling light shows are actually carefully crafted chemical reactions. This week's Reactions episode features John Conkling, Ph.D., the professor who literally wrote the book on pyrotechnics. In the video, Conkling explains the chemistry that creates those amazing fireworks displays. The video is available at www.youtube.com/watch?v=nPHegSulI_M.