Today in 1976, US Patent 3946780 A was issued, an invention of John C. Sellers, for his “Fermentation Container.” Here’s the Abstract:

A flexible fermentation container which has, in place of the common air lock, a diaphragm having a Gurley porosity of 2 to 120 seconds. The diaphragm material, such as spun bonded polyethylene, allows fermentation gases to pass out of the container, but does not allow bacteria or other contaminants to enter.