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Gas Lighting
Brief description
Gas lighting produces artificial light through the combustion of flammable gas, such as coal gas, syngas, or natural gas. Before widespread electrification, it enabled bright, central, and continuous illumination for homes, factories, and public streets.
Use / Function
- Municipal Street Lighting: Safely illuminating urban thoroughfares and public spaces after dark.
- Industrial Scale: Extending working hours in factories, mills, and workshops.
- Domestic Lighting: Providing clean, steady indoor illumination compared to candles or open oil lamps.
Operating principle
- Pyrolysis / Gasification: Bituminous Coal or biomass is destructively distilled in an airtight Retort heated by fire.
- Purification: The released volatile gas passes through condensers and scrubbers to remove tar, ammonia, and sulfur compounds.
- Storage & Distribution: Purified gas is collected in a Gasometer and fed through pipes under steady low pressure.
- Combustion: The gas is ignited at a burner nozzle, where controlled mixing with air produces a bright flame or heats a gas mantle to incandescence.
How to create it
- Retort Assembly: Seal dry bituminous coal inside a heavy Cast Iron or clay vessel fitted with an outlet pipe, and heat it over a furnace.
- Cooling & Scrubbing: Run the exiting gas pipe through a water bath (condenser) to drop out coal tar, then bubble it through a chamber filled with slaked Lime or water to scrub out hydrogen sulfide and carbon dioxide.
- Gas Holder: Invert a bell container in a water tank (a simple Gasometer) to collect the scrubbed gas and maintain steady pressure.
- Distribution Pipe: Connect metal or Copper piping from the gasometer to the burner location.
- Burner Nozzle: Fit a small ceramic or metal tip with tiny orifices (fishtail or argand burner) enclosed in a Glass chimney to protect the flame.
Materials needed
- Essential Materials: Coal or biomass, Cast Iron, Lime, Copper or lead piping, Glass.
- Tools: Furnace/forge, pipe fittings, sealing clay, water baths.
- Substitutes: Wood or animal fat can be used for gasification if coal is unavailable.
Variants and improvements
- Early Open Burners: Simple batwing or fishtail burners that burned raw coal gas with moderate brightness.
- Welsbach Incandescent Mantle: Introduced a fabric mesh soaked in rare-earth oxides (thorium/cerium) placed over the flame, increasing light output dramatically while using less gas.
- Modern Natural Gas Lamps: Used for decorative or off-grid outdoor lighting.
Limits and risks
- Explosion & Fire: Gas leaks in enclosed spaces pose severe explosion risks.
- Toxicity: Raw coal gas contains high amounts of poisonous carbon monoxide.
- Asphyxiation & Air Quality: Burning gas depletes oxygen in unventilated rooms and produces harmful combustion byproducts.