I knew that 'gas' was short for 'gasoline' (Wikipedia has some interesting little factoids on the derivation and etymology of the word: it seems it caught on in American because, in the late C19th, 'petrol' was a trade name) but that didn't stop my first reaction being annoyance upon hearing -- on film, for instance -- petrol being called gas, on the grounds that petrol is a liquid not a gas.Now I