Place three or four pieces of charcoal fire inside, and use four fire bricks original: "huo zhuan." These were pre-cast blocks of slow-burning incendiary material, often containing sulfur, saltpeter, and binders like oil or wax. together.

Use warm ash to bank up the contents; use one hundred [portions] of ash The "one hundred" likely refers to a specific weight or volume measure used by military engineers of the time to ensure the proper insulation and burn rate..

It is absolutely vital that you do not fill the bowl to the brim. If it is filled to the top, the interior becomes too compressed, which will cause the bowl to burst outward The author warns that without air space, the internal pressure from the igniting charcoal and gas would shatter the ceramic bowl prematurely rather than allowing for a controlled burn..

The Lid

The lid should be flush and not protrude. Place it directly on the surface of the gunpowder so that when the device is thrown or dropped, the powder does not scatter or spill.
Securely cover it with the lid.

Design of the Fire Brick

Fire bricks were the "batteries" of Ming dynasty incendiary warfare—stable, portable blocks of chemical fuel that could be ignited and used to set enemy structures or ships ablaze.

Bamboo tube for threading the fuse
original: "zhu tong chuan yao xian." A small bamboo pipe was used as a guide and protective sleeve for the match cord (fuse) to ensure it reached the core of the explosive without being extinguished or snagged.

The Wrapped Style
original: "bao shi." This refers to the method of wrapping the chemical block in paper or cloth treated with resin to make it waterproof and easier to handle before deployment.