Ethyne (acetylene) is generally prepared in a laboratory by the action of water on calcium carbide.
Procedure:
A thin layer of sand is spread atomic the bottom of a conical flask. A few small pieces of calcium carbide (CaC2) are placed over the sand. The whole apparatus is set upon. Water is added to the flask drop wise with the help of a thistle funnel. Ethyne (acetylene) gas so produced is collected in a gas jar by the downward displacement of water.