HTML Coding

I just noticed the other day that some of my HTML coding was only working in Explorer and not Firefox.

The code "font face ="symbol"" which I use to display the symbol for Ohm, or what ever, only works with Internet Explorer. In firefox, the alpha character and not the symbol is displayed.

Any how, I'm not going to fix it, because I don't know what the fix is. Not yet sure if this is invalid code or just an issue with firefox.....