"The air pump is an instrument for removing a gas from a closed vessel, the essential parts are shown." -Avery 1895

Air Pump

"The air pump is an instrument for removing a gas from a closed vessel, the essential parts are shown."…

"Invert the second vessel over the first, mouth to mouth, so that the contents of the two vessels shall be separated only by the paper. Each vessel is filled with an invisible gas. Remove the paper, and notice that the invisible gases quickly-diffuse into each other and form a dense cloud." -Avery 1895

Mixing Gases in Inverted Containers

"Invert the second vessel over the first, mouth to mouth, so that the contents of the two vessels shall…

"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,…