A clue to the composition of the Kallinikos mixture may perhaps be found in its Greek name, “sea-fire” or “wet-fire.” One substance had long been known with whose combustion water was closely connected—quicklime, and with its properties Kallinikos, as an architect, must have been perfectly familiar. Its temperature rises—to 150° C. (302° F.) if the quantity be large—when sprinkled with water, and it can consequently be employed to ignite substances with low points of ignition. For example, if a mixture of quicklime and naphtha be thrown into water, the rapid rise in temperature of the lime causes a sudden and strong development of vapour from the naphtha, which on mixing with the air becomes highly explosive. Such a mixture, it is almost unnecessary to add, could not be handled with safety _after_ it has been wet. Plutarch was aware of the explosive nature of naphtha vapour. “Naphtha,” he says, “is like bitumen, and is so easy to set on fire that, without touching it with any flame, it will catch light from the rays which are sent forth from a fire, burning the air which is between both.”[74] Pliny speaks of the heat developed by quicklime when sprinkled with water. “It is strange,” he says, “that what has already been burnt should be ignited by water” (_mirum aliquid, postquam arserit, accendi aquis_).[75] The same property is implicitly referred to in the “Kestoi,” attributed to Sextus Julius Africanus of Emaus, who lived under Alexander Severus, 222-235. The military portions of this work, however, must have been written long afterwards, in the end of the sixth or the beginning of the seventh century at the earliest; for Belisarius, who was born in 505, is mentioned in the sixty-sixth chapter.[76] In the forty-fifth chapter there is a recipe for a quicklime-asphalt composition, which is called “automatic fire.” This mixture was used by jugglers to exhibit “spontaneous combustion,” a little water being secretly poured on a plate on which a ball of the composition was placed.[77] It contained very little quicklime (παντελῶς ὀλίγον). Cameniata tells us that at the storming of Salonika in 904 the Moslems threw “pitch and torches and quicklime” over the walls.[78] By “quicklime” he probably meant the earthenware hand grenades, filled with wet quicklime, described by the Emperor Leo, who then sat on the throne (886-911). “The vapour of the quicklime,” he says, “when the pots are broken, stifles and chokes the enemy and distracts his soldiers.”[79] The simplest and most probable explanation of the nature of the sea-fire then is, that it was a sulphur-quicklime-naphtha mixture of the same family as those shown in the following Table. TABLE III. _Sea-Fires._