Gunpowder weapons The
Wujing Zongyao records detailed descriptions of gunpowder weapons such as incendiary projectiles,
smoke bombs,
fire arrows, and
grenades. It documents incendiary projectiles containing low-nitrate gunpowder, which were launched from catapults or lowered down from city walls onto besiegers. Examples of these incendiaries include the "swallow-tail" incendiary (;
yanweiju) and the flying incendiary (;
feiju). The swallow-tail incendiary was made of straw tied together and dipped in fat or oil. Chinese soldiers defending a city under siege would light the incendiary and lower it onto any wooden structure of the invading army to engulf it in fire. The flying incendiary visually resembled the swallow-tail incendiary, but was lowered using an iron chain from a
swape lever installed within the walls of the city. The book also describes an 'igniter ball' used in warfare and for finding the firing range. The
Wujing Zongyao stated the following: Gunpowder was attached to fire arrows () and utilized as an incendiary. The
Wujing Zongyao records that fire arrows were launched from bows or crossbows. The gunpowder used for fire arrows was likely a low-nitrate powder, and the quantity of gunpowder varied according to the type of bow. In the book, the force of gunpowder is said to be enough to launch an arrow, but only when the elasticity of the crossbow is sufficient. The
Wujing Zongyao discusses various types of incendiary bombs and grenades. They used a low-nitrate gunpowder that, while not powerful enough to cause an explosion, was effective for incendiary weapons. The
huoqiu (; literally "fire ball") was filled with gunpowder and launched using a trebuchet. Upon impact, the
huoqiu would start a fire among an invading army. Chinese bombs such as the thunder clap bomb or
pili pao used a greater percentage of gunpowder than that of the
huoqiu. The gunpowder mixture for a bomb was placed within a rigid container that held in the expanding gas, allowing for more powerful explosions. The thunder clap bomb was constructed with a container made from bamboo. In the
Wujing Zongyao and other military texts, the distinction between a bomb and a grenade is ambiguous. At the time, the Chinese usually did not categorize gunpowder weapons according to their delivery method. One of the few exceptions is the
shoupao, or hand bomb, which is analogous to the hand grenade.
Formulas Gunpowder had already been invented prior to the
Wujing Zongyao by Chinese alchemists in the 9th century. Early references to gunpowder can be found in the Daoist book
Zhenyuan miaodao yaolue, written circa 850, and gunpowder was utilized in Chinese warfare as early as the 10th century in
fire arrows and
gunpowder fuses used to light the Chinese two-piston
flamethrower. However it was not until the
Wujing Zongyao that the exact chemical formulas for early Chinese gunpowder were revealed. The
Wujing Zongyao contains three formulas for gunpowder: one for an explosive bomb launched from a
trebuchet, another for a similar bomb with hooks attached so that it could latch on to any wooden structure and set it on fire, and another formula specified for a poison-smoke bomb used for
chemical warfare. The
Wujing Zongyao's first recorded gunpowder formula used in these bombs held a
potassium nitrate level of 55.4% to 55.5%, sulfur content of 19.4% to 26.5%, and
carbonaceous content of 23% to 25.2%. The first step for making gunpowder is to powder and mix together sulphur, saltpetre, charcoal, pitch, and dried lacquer. Tung oil, dried plants, and wax are mixed next to create a paste. The paste and powder are combined and carefully stirred. Then the mixture is placed inside a paper container, wrapped up, and tied using hemp twine. Several precautions are taken to prevent the gunpowder from becoming damp. For the second formula, the inner ball alone had a nitrate percentage of 61.5% to 50.2%, a sulfur content of 30.8% to 25.1%, and if all carbonaceous matter was taken, 24.7%, if just taking the charcoal content alone, the carbon level was 7.7%. If the outer coating and inner ball are both included with the second black-powder formula, that would yield a nitrate level of 34.7% to 54.8%, a sulfur content of 17.4% to 27.4%, and if all carbonaceous material is used, 47.9% carbon, if only charcoal is used, 17.8%. If the inner ball of the third black-powder formula is only considered, it held nitrate levels of 39.6% if all carbonaceous matter was taken, 49.4% nitrate if excluding the poisons, and 60% if charcoal is specified alone. The sulfur content was 19.8% if all carbonaceous matter was considered, 24.7% if this excluded poisons, and 30% if charcoal is specified alone. The carbon content was 40.5% if all carbonaceous matter was considered, 25.9% if this excluded poisons, and 10% if charcoal alone was specified. If both the inner ball and outer coating are considered for the third formula, that would yield a nitrate level of 27% if all carbonaceous matter was taken, 31.2% if this excluded poisons, and 51.7% if charcoal alone was used. The sulfur content would be 13.5% if all carbonaceous matter was taken, 15.6% if this excluded the poisons, and 25.9% if only charcoal alone was specified. The carbon content was 59.5% if all carbonaceous matter was taken into account, 53.2% if this excluded poisons, and 22.4% if charcoal alone was specified. The first black-powder concoction was simply labeled as the "method for making the fire-chemical", with its ingredients and measured weight (in
ounces) of each ingredient listed in the section below with the others listed in similar fashion.
Fireball formula •
Sulfur (14 oz.) • Wo huang ('nest yellow', perhaps nodular sulfur) (7 oz.) •
Saltpetre (40 oz.) •
Hemp roots (1 oz.) • Dried
lacquer (1 oz.) •
Arsenic (1 oz.) • White
lead (
lead carbonate) (1 oz.) •
Bamboo roots (1 oz.) •
Minium (
lead tetroxide) (1 oz.) • Yellow
wax (0.5 oz.) • Clear
oil (0.1 oz.) •
Tung oil (0.5 oz.) •
Pine resin (14 oz.) • Thick oil (0.1 oz.) Total weight = 82.2 oz.
Caltrop fireball formula Inner ball •
Sulphur (20 oz.) •
Saltpetre (40 oz.) • Coarse
charcoal powder (5 oz.) •
Pitch (2.5 oz.) • Dried
lacquer (pounded to powder) (2.5 oz.) •
Bamboo roots (1.1 oz.) •
Hemp roots, cut into shreds (1.1 oz.) •
Tung oil (2.5 oz.) • Lesser oil (possibly an edible oil) (2.5 oz.) •
Wax (2.5 oz.) Total weight of inner ball = 79.7 oz. Outer coating •
Paper (12.5 oz.) •
Hemp (fibre) (10 oz.) •
Minium (1.1 oz) •
Charcoal powder (8 oz.) • Pitch (2.5 oz) • Yellow wax (2.5 oz) Total weight of outer coating = 36.6 oz. Total weight = 116.3 oz.
Poisonous smoke ball formula Inner ball •
Sulphur (15 oz.) •
Saltpetre (30 oz.) •
Aconite (
aconitum fischeri) (5 oz.) •
Croton oil (croton tiglium) (5 oz.) • Wolfsbane (
aconitum ferox or lycoctonum) (5 oz.) •
Tung oil (5 oz.) • Lesser oil (2.5 oz.) •
Charcoal powder (5 oz.) •
Pitch (5 oz.) •
Arsenic (2 oz.) • Yellow
wax (1 oz.) •
Bamboo roots (1.1 oz.) •
Hemp roots (1.1 oz.) Total weight of inner ball = 77.7 oz. Outer coating • Old
paper (12.5 oz.) •
Hemp (stalk) skin fibre (10 oz.) •
Pitch (2.5 oz.) • Yellow
wax (2.5 oz.) •
Minium (1.1 oz.) •
Charcoal (8 oz.) Total weight of outer coating = 36.6 oz. Total weight = 114.3 oz. ==Double-acting piston flamethrower==