Either. i agree with those on the right, but I felt that there should be some points on the 'Aluminium' side. It seemed kind of unfair for this argument to seem to be winning on the American side when the British is just as correct.

I'm used to calling it aluminium, and will continue calling it that. It feels more right to me, it sings in my ears, it resonates in my soul, etc :P

But as with all words that have accepted spelling variations, I wouldn't object to someone who used a different variant from me, as long as they consistently use the variant they picked.

Taken from http://scienceblogs.com/worldsfair/2009/ 04/aluminum_versus_aluminium_wher.php

The reason why there were two ways of saying the element aluminum/aluminium has always been one of the those things that made me go "hmmm" But by the same token, it's also always been one of those things that never stuck around in my consciousness long enough for me to look it up.

Well, lucky for all us, Michael Quinion over at World Wide Words does an awesome job of going into the lexicon of these words, paying particular attention to why two forms exist - specifically, why the Brits say "Alumininium" and why Americans say "Aluminum."

It's actually quite intriguing how it came to be - first starting with Sir Humphry Davy's not being able to make a decision:

Sir Humphry made a bit of a mess of naming this new element, at first spelling it alumium (this was in 1807) then changing it to aluminum, and finally settling on aluminium in 1812. His classically educated scientific colleagues preferred aluminium right from the start, because it had more of a classical ring, and chimed harmoniously with many other elements whose names ended in -ium, like potassium, sodium, and magnesium, all of which had been named by Davy.

And why it stuck in the "aluminum" form within the United States, had more to do with publications like the Noah Webster's Dictionary which in 1828 listed only the -um form in its pages. Such preferences crops up here and there during this time in history and also included the 1913 edition of the Unabridged version.

In any event, it was regarding this period of time, that Quinion writes:

It's clear that the shift in the USA from -ium to -um took place progressively over a period starting in about 1895, when the metal began to be widely available and the word started to be needed in popular writing. It is easy to imagine journalists turning for confirmation to Webster's Dictionary, still the most influential work at that time, and adopting its spelling. The official change in the US to the -um spelling happened quite late: the American Chemical Society only adopted it in 1925, though this was clearly in response to the popular shift that had already taken place. The International Union of Pure and Applied Chemistry (IUPAC) officially standardised on aluminium in 1990, though this has done nothing, of course, to change the way people in the US spell it for day to day purposes.

Anyway, there you have it- looks to me like it was all Webster's fault.