The speech standard of the Ming and Qing empires was called Mandarin language by European missionaries, translating the Chinese name Guanhua (the language of the officials) for this speech standard, which was current already in the Ming Dynasty.
Producer gas is made by blowing air through an incandescent fuel bed (commonly coke or coal) in a gas producer. The reaction of fuel with insufficient air for total combustion produces carbon monoxide (CO); this reaction is exothermic and self-sustaining.
Decide on fuel. Most fire pits are either wood-burning or use gas/propane, and it's important to decide on which type you want. One of the biggest benefits of a wood fire pit is that it can be much more cost-efficient than buying propane tanks constantly (for pits that can be hooked up like a grill).