Correction:
Gadget Boy points me to this description of the 'gas injector' widgit inside Guinness and Beamish cans. It injects nitrogen not carbon dioxide.
That makes sense, because CO2 would ruin the taste of the beer with it's acidity. (The Guinness element symbol is from The Beeriodic Table.)
Looking through my notebooks, I found this drawing of Antares' spectrum from nearly a decade ago (8/94):
