What with text messaging, Twitter and Facebook, you might think that we had exhausted all the latest ways to communicate without speaking. Think again, because soon you might prefer to use an "infofuse". Infofuses are a bit like a multi-coloured version of Morse code. A message is encoded as a series of dots and dashes on a simple strip of paper. The dots and dashes are composed of three alkali metals – lithium, rubidium and caesium – each of which burns with a characteristic color.