Wine

[lobogotti]

The problem has always been the fact that draught Guinness is (or should be) dispensed with a mixture of Nitrogen and CO2 gasses rather than the conventional CO2 alone. The nitrogen is used because it makes very fine bubbles while it is not absorbed into the brew as the CO2 is, thus it does not "over-carbonate" the beer. Also a special faucet is preferred which, in combination with the gasses, creates that wonderful creamy brown head which lasts to the bottom of the glass


http://www.csd.uwo.ca/faculty/barron/guinness_can.html