Mercury Seal
The first technological use of a glass-to-metal seal was the encapsulation of the vacuum in the barometer by Torricelli. The liquid mercury wets the glass and thus provides for a vacuum tight seal. Liquid mercury was also used to seal the metal leads of early mercury arc lamps into the fused silica bulbs.
A less toxic and more expensive alternative to mercury is gallium.
Mercury and gallium seals can be used for vacuum-sealing rotary shafts.
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Famous quotes containing the words mercury and/or seal:
“The mercury sank in the mouth of the dying day.
What instruments we have agree
The day of his death was a dark cold day.”
—W.H. (Wystan Hugh)
“You sir, will bring down that renowned chair in which you sit into infamy if your seal is set to this instrument of perfidy; and the name of this nation, hitherto the sweet omen of religion and liberty, will stink to the world.”
—Ralph Waldo Emerson (1803–1882)