Liuhuang Yanxiao 硫磺燄硝 [sulphur and saltpeter]

Liuhuang means sulfur and yanqiao means saltpeter, and they are both flammable solids, which will very readily catch on fire. In ancient China, sulfur and saltpeter were usually used to set a fire and often appear together in traditional Chinese literature as the common phrase liuhuang yanqiao. For easy understanding and readability, here we directly use “flammable materials” to refer to liuhuang yanxiao  硫磺燄硝  [sulfur and saltpeter].