Greer Fire , a name applied to compounds that burn on the surface of or under water. A summary of what is said about it in old writers is given by Gibbon in the "Decline and Fall of the Roman Empire," chap. lii. The subject is also ably treated by Dr. McCulloch in vol. xiv. of the "Quarterly Journal of Science." The Greek fire was most advantageously employed in the defence of Constantinople during the two sieges by the Saracens of A. D. 668 675 and 716-718. The secret of its preparation and use was derived from Callinicus, a deserter from the service of the caliph to that of the emperor. It appears to have been a compound of bitumen, sulphur, and pitch, and to have been poured from caldrons, or projected in lire balls, or on arrows and javelins around which flax was twisted saturated with the inflammable compound. It was vomited through long copper tubes from the prows of fire ships. These were themselves consumed, as they sent fire and destruction among the galleys of the enemy. For 400 years its secret was successfully preserved by the Romans of the East, the vengeance of heaven being imprecated upon whomsoever should divulge this composition, which the people were taught to believe was revealed by an angel to the first of the Constantines. The Mohammedans finally obtained the secret, and in the crusades turned the art against the Christians. Joinville in his Histoire de St. Louis describes the fire as coming through the air like a winged long-tailed dragon, about the thickness of a hogshead, with the report of thunder and the velocity of lightning, producing so much light from the quantity of fire it threw out, that one might see in the camp as if it had been day.

Its use was continued till the middle of the 14th century, when it gave place to gunpowder. - M. Niepco de St. Vic-tor experimented, by request of the French minister of war, upon the property of benzole of burning upon water and igniting if a bit of potassium or of phosphuret of calcium be contained in it. On this principle he made an inextinguishable lamp, to be ignited by immersion under water, for attachment to buoys and life preservers. He found that if a glass vessel containing 300 grammes of benzole and half a gramme of potassium were broken on the surface of the water, the benzole would immediately overspread a considerable surface, bursting at the same time into flame. A mixture of three parts of benzole and one of sulphuret of carbon, being put into a hand grenade previously heated by immersion in boiling water, produced a disengagement of vapor, which could be ignited and would continue to burn from a jet until the whole was consumed. Phosphorus in solution increases its power of setting fire to other objects. Petroleum may be substituted for the benzole. It was thought that this might be used in naval warfare as the ancient Greek fire was employed. It was tried by the Paris commune in 1871, under whose direction many thousand petroleum bombs were thrown with disastrous effect.

The subject is fully treated by Scoffern in his "Projectile Weapons of War and Explosive Compounds" (London, 1858), in which he also names several liquid mixtures that spontaneously ignite, and may be used for the same purposes as Greek fire. A solution of phosphorus in sulphuret of carbon thrown in a glass grenade was found, in experiments conducted at Woolwich, to ignite soon after the liquid was scattered. Chloride of sulphur may be substituted for the sulphuret of carbon, the ignition not taking place quite so soon, thus giving time for the liquid to penetrate into woodwork and canvas. An abominable odor is diffused during the combustion. The arsenical alcohol, described under Kakodyle, is proposed for a similar purpose, the fumes from which would greatly add to its deadly effects.