Lets see if I can get some use out of my chemistry degree. Nitrogen is not a nobel gas. The noble gases are the ones from Group VIII of the periodic table (helium, neon, argon, krypton, xenon, and radon which is radioactive). Nitrogen gas exists as a dimer, N2, and in this form it is very stable. I would think nitrogen gas would be fine to keep moisture out of a watch and would not react with any materials or lubricants in a watch.
I think the use of argon is a little mix between science and marketing. While an argon atom is heavier than nitrogen, oxygen, or water gas molecule, I'm not sure one argon atom takes up more space than a dual-atom molecule of nitrogen or oxygen gas. Gollnick, you are right that krypton or xenon would be better than argon. In any case, most of the time when preserving or protecting anything, the main thing you want to do is prevent contact with oxygen, whether its O2 or the oxygen in H2O.
Alan
I think the use of argon is a little mix between science and marketing. While an argon atom is heavier than nitrogen, oxygen, or water gas molecule, I'm not sure one argon atom takes up more space than a dual-atom molecule of nitrogen or oxygen gas. Gollnick, you are right that krypton or xenon would be better than argon. In any case, most of the time when preserving or protecting anything, the main thing you want to do is prevent contact with oxygen, whether its O2 or the oxygen in H2O.
Alan