1.   That released the firing pin, which in turn fired the percussion cap and triggered a chemical reaction that generated oxygen.

2.   It is bacteria that have generated the oxygen we breathe on earth.

3.   As well as housing thousands of species of algae, fish and molluscs, the sea grass generates oxygen and has been dubbed the lungs of the sea.

4.   Earlier this week, the difficulty forced the Mir crew to begin igniting lithium perchlorate candles to generate oxygen for breathing.

5.   Guest American astronaut Jerry Linenger and his two cosmonaut hosts will use the tools to try and repair a leaky cooling system and a device that generates breathing oxygen.

6.   Linenger and his cosmonaut hosts have had to rely on the controlled combustion of lithium perchlorate candles to generate breathing oxygen.

7.   Nonessential systems aboard Mir were shut off and a backup system was being used to generate oxygen.

8.   Plants also convert carbon dioxide into carbon, which becomes a building block for themselves, and generate oxygen as a by-product.

9.   The blaze was blamed on a leaky canister of chemicals intentionally ignited to generate oxygen for breathing.