page_title: Pneumatic trough
hierarchical_section_title: Pneumatic trough
caption_attribution_description: English: Scan from an old book, showing an early pneumatic trough
context_page_description: A pneumatic trough is a piece of laboratory apparatus used for collecting gases, such as hydrogen, oxygen and nitrogen. Pneumatic troughs require a liquid such as water. Scientists also have used mercury in pneumatic troughs, but usually only for the collection of water-soluble gases. Health and safety issues surrounding mercury generally prohibit its use in modern-day pneumatic troughs.
  Four items are required for gas collection with a pneumatic trough:
  The trough itself, which is a large glass dish or a similar container
  A gas bottle, to hold the gas collected
  A way to support the gas bottle or bulb, such as a Beehive shelf or a hanger
  A liquid in the trough
  The bottle is filled with water, inverted, and placed into the pneumatic trough already containing water. The outlet tube from the gas-generating apparatus is inserted into the opening of the bottle so that gas can bubble up through it, displacing the water within.
context_section_description: A pneumatic trough is a piece of laboratory apparatus used for collecting gases, such as hydrogen, oxygen and nitrogen.  Pneumatic troughs require a liquid such as water.  Scientists also have used mercury in pneumatic troughs, but usually only for the collection of water-soluble gases.  Health and safety issues surrounding mercury generally prohibit its use in modern-day pneumatic troughs.
  Four items are required for gas collection with a pneumatic trough:
  The trough itself, which is a large glass dish or a similar container
  A gas bottle (or bulb), to hold the gas collected
  A way to support the gas bottle or bulb, such as a Beehive shelf or a hanger (see picture)
  A liquid in the trough
  The bottle is filled with water, inverted, and placed into the pneumatic trough already containing water.  The outlet tube from the gas-generating apparatus is inserted into the opening of the bottle so that gas can bubble up through it, displacing the water within.
caption: Pneumatic trough, as invented by Stephen Hales
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