ὑγρὸν πῦρ -- "Liquid Fire"

One ancient version of napalm, or liquid fire (also commonly called "Greek Fire"), was utilized extensively by the Byzantine empire from the 6th through 13th century. Its invention is often attributed to Kallinikos, but historical record casts some doubt on this claim. The weapon itself is some mixture of flammable material which could burn on/in water, and was only extinguished through oxygen depletion or chemical reaction. The actual composition of Greek Fire remains an historical mystery. Liquid fire could be hurled in containers, a la the Molotov Cocktail, or sprayed through pressure-pumped cylinders and ignited in-stream, like a modern flamethrower.

   At what period the ancient Greek fire was invented has never been certainly determined. There are many writers who place the invention in a far antiquity. Historical details have been adduced pointing to the period of the earlier wars between the Greeks and Romans as the true era of the discovery. But we do not find any certain evidence of the use of Greek fire until the sieges of Constantinople, in the seventh and eighth centuries, though a Father of the Christian Church, writing in the fifth century, gave receipts for making a combustible substance of similar qualities from the compounds resin, sulphur, pitch, pigeon's dung, turpentine, and the juice of the herb 'all-heal.'

It is related that the true Greek fire was invented by a certain Callinicus, an architect of Heliopolis, in Syria (Baalbec), in 678. The secret of the composition of this artificial flame, and the art of directing its action, were imparted by Callinicus---who had deserted from the Caliph---to the Emperor of Constantinople. From this period until the year 1291 the use of Greek fire was an important element in the military power of the Byzantine empire. The progress of the Saracens was, more than once, decisively checked by the destructive action of this powerful and terrible flame. The important art of compounding the fire 'was preserved at Constantinople,' says Gibbon, 'as the palladium of the state: the galleys and artillery might occasionally be lent to the allies of Rome; but the composition of the Greek fire was concealed with the most zealous scruple, and the terror of the enemy was increased and prolonged by their ignorance and surprise.'

The accounts which have reached us respecting the properties of the Greek fire are such as to justify the high value attached by the Byzantine emperors to the secret of its composition. It was a liquid, which was propelled by various methods against the ships or engines of the enemy. So long as it was kept from the air, or remained in large masses, the liquid appears to have been perfectly safe from combustion; but as soon as it was poured forth it burned with an intense flame which consumed everything around---not merely burning upwards, but with equal fury downwards and laterally. Water not only failed to quench it, but made it burn with new ardour. To subdue the flames it was necessary to employ, in large quantities, either sand or vinegar. Various methods were employed for propelling the liquid fire towards the enemy. Sometimes it was enclosed in vessels made of some brittle substance, and these were flung at the enemy by means of suitable projectile machines. 'It was either,' says Gibbon, 'poured from the rampart in large boilers, or launched in red-hot balls of stone and iron, or darted in arrows and javelins, twisted round with flax and tow, which had deeply imbibed the inflammable oil.' But the effectual use of the destructive compound seems to have been best secured by means of a species of fire-ships specially constructed for the purpose. Copper and iron machines were placed in the fore-part of these ships. Long tubes, fantastically shaped, so as to resemble the mouth and jaws of savage animals, formed the outlet for a stream of liquid fire, which the engine---literally a fire- engine---propelled to a great distance. Hand-engines were also constructed by which the destructive compound could be spurted by the soldiers, Beckman tells us.

The secret, as we have said, was carefully kept by the Byzantines. The emperor Constantine suggested the answers which in his opinion were best fitted to elude the pertinacious questioning of the barbarians. 'They should be told that the mystery of the Greek fire had been revealed by an angel to the first and greatest of the Constantines, with the sacred injunction that this gift of Heaven---this peculiar blessing of the Romans---should never be communicated to any foreign nation; that the prince and subject were alike bound to religious silence under the temporal and spiritual penalties of treason and sacrilege; and that the infamous attempt would provoke the sudden and supernatural vengeance of the God of the Christians.' Gibbon adds that the secret thus religiously guarded was 'confined for above 400 years to the Romans of the East; and at the end of the eleventh century the Pisans to whom every sea and every art were familiar suffered the effects without understanding the composition of Greek fire.' ^[1] 

 1. Proctor, Richard A. The Universe of Suns and Other Science Gleanings. R. Worthington: New York. 1884.

 _