The "Huolongjing"'s primary contribution to gunpowder was in expanding its role as a chemical weapon. Jiao Yu proposed several gunpowder compositions in addition to the standard potassium nitrate (saltpetre), sulphur, and charcoal. Described are the military applications of "divine gunpowder", "poison gunpowder", and "blinding and burning gunpowder." Poisonous gunpowder for hand-thrown or trebuchet launched bombs was created using a mixture of tung oil, urine, sal ammoniac, feces, and scallion juice heated and coated upon tiny iron pellets and broken porcelain. According to Jiao Yu, "even birds flying in the air cannot escape the effects of the explosion".