The molecular disperser was a piece of technology employed by the Silurians. This device was capable of dispersing the Van Allen belt around the planet Earth, allowing for radiation to burn the world's warm-blooded life forms, such as humans, while the reptilian Silurians could live. After the humans, with the aid of the Third Doctor, discovered a cure for the Silurian plague, the new leader decided to employ the disperser as a different way of exterminating the human race.