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)
“To believe in something not yet proved and to underwrite it with our lives: it is the only way we can leave the future open. Man, surrounded by facts, permitting himself no surmise, no intuitive flash, no great hypothesis, no risk, is in a locked cell. Ignorance cannot seal the mind and imagination more surely.”
—Lillian Smith (1897–1966)