The vacuum bottle included in them, however, steadily evolved during the course of the decade and into the 1970s.
From the en.wikipedia.org
What was originally a steel vacuum bottle with glass liner, cork or rubber stopper, and bakelite cup became an all-plastic bottle, with insulated foam rather than vacuum.
From the en.wikipedia.org
Ever since Serena stepped on a beer bottle in Germany, there has been a vacuum in the women's game.
From the telegraph.co.uk
They also found out that heat will expand gases inside a bottle and when the gases are pushed out a vacuum is created, which pulls a boiled egg into the bottle.
From the tennessean.com
An opened bottle goes into one of the unit's two compartments, where an internal vacuum cylinder slides over the bottleneck.