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"If it be required to separate the helium which is often found in the gases given off by a thermal spring, they are subjected to the action of charcoal cooled with liquid air. The result is the absoption of the less volatile constituents, i.e., all except hydrogen and helium. The gaseous residue, with the additon of oxygen is then sparked, and the water thus formed is removed together with the excess oxygen to leave only helium." —The Encyclopedia Britannica 1910

Apparatus Used to Seperate Volatile Gases

"If it be required to separate the helium which is often found in the gases given off by a thermal spring,…

A mop that wrings itself of excess water.

Self-Wringing Mop

A mop that wrings itself of excess water.