| Answer | Crossword Clue |
|---|---|
| rarities | thinness, as of air or a gas |
| bubble | An air- or gas-filled spherical cavity in a liquid or a solidified liquid such as glass or amber |
| bubbles | An air- or gas-filled spherical cavity in a liquid or a solidified liquid such as glass or amber |
| ballonets | The compartment in a balloon or airship into which air or another gas can be forced in order to maintain the craft's shape as buoyant gas is released |
| mixtures | The charge of gas or vapor mixed with air that is admitted to the cylinder of an internal combustion engine, esp. as regards the ratio of fuel to air |
| inflator | to fill with air or gas so as to expand |
