The so-called Greek Fire is a Byzantine invention: Kallinikos was said to be the inventor of the liquid fire that saved Constantinople from the Arabs in 678 and from the Rus in 941.Its exact composition and means of propulsion are still uncertain, especially since the term "Greek fire" was used to refer to various types of incendiary weapons. The most likely ingredient included crude oil obtained from regions east of the Azov Sea or from wells east of Armenia, mixed with resin and sulphur, which was then heated and propelled by a pump (siphon) through a bronze tube (strepton). The liquid jet was ignited either as it left the tube or by flaming projectiles fired after it. The Byzantines were careful never to divulge details on the composition or propulsion of Greek fire; thus even when the Bulgars captured a great supply of thew mixture and firing tubes they were unable to use them