Compendium of Military Preparations, Volume 123
Page 6

The Divine Oil Jar for Flying through the Air and Gliding across Water

original: 飛空滑水神油罐 (Feikong Huashui Shenyou Guan). This name describes the weapon's versatile trajectory: it could be lobbed through the air or skipped across the water's surface like a stone.

This weapon is a specialized incendiary jar original: 火罐 (huoguan); a generic term for ceramic or metal vessels packed with gunpowder and combustible oils. designed for naval engagements. The vessel is typically constructed from a rounded clay or thin iron pot, chosen for its ability to shatter upon impact and spread its burning contents.

The exterior of the jar is encased in a woven rope harness, which provides a grip for the soldier to swing and hurl the device with significant centrifugal force. At the crown of the vessel, a waterproof fuse is inserted into the priming hole original: 火口 (huokou), literally 'fire mouth'.

When deployed against an enemy fleet:
1. The fuse is lit just before the jar is thrown.
2. If aimed at the deck, the "Flying through the Air" technique is used, lobbing the jar in a high arc to crash onto the enemy's wooden superstructure.
3. If aimed at the hull, the "Gliding across Water" technique is employed. By throwing the jar at a shallow angle, it is intended to skip along the surface of the waves—much like a skipping stone—until it strikes the side of an enemy ship at the waterline, where the resulting fire is most difficult to extinguish.

The "Divine Oil" contained within is a potent mixture of sulfur, saltpeter, and resinous oils The 'oil' often included petroleum products or distilled oils that would float and continue burning even if the jar hit the water before the target.. This ensures that even if the jar breaks prematurely, the burning oil will spread across the water, creating a literal "sea of fire" to block or ignite the approaching enemy.