Greek fire

Greek fire was an incendiary chemical weapon manufactured in and used by the Eastern Roman Empire from the seventh through the fourteenth centuries. The recipe for Greek fire was a closely-guarded state secret, but historians speculate it may have been made by combining pine resin, naphtha, quicklime, calcium phosphide, sulfur, or niter. Roman sailors would toss grenades loaded with Greek fire onto enemy ships or spray it from tubes. Its ability to burn on water made it an effective and destructive naval incendiary weapon, and rival powers tried unsuccessfully to copy the material.