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.
Natural gas also burns cleaner than fuel oil. Emissions produced by natural gas combustion are far less harmful than those produced by oil, coal and wood. No fuel tanks are required for delivery, reducing the risk of leaks polluting land and groundwater. Despite the safe properties of natural gas, like all combustion fuels or materials it is flammable and can produce carbon monoxide when trapped in a confined space and there is an inadequate supply of oxygen.