In his Chemistry Blog azmanam described an absolutley invaluable dictionary of chemical terms he had created consisting of over 100,000 words. The original compilation is compatible with Microsoft Office (Windows or Mac), and Open Office (Windows or Linux). I thought it would be useful to convert the dictionary to a format that would be compatible with iWork, (actually I think it is used by all Mac OS X applications). The dictionary used by iWork is "username/Library/Spelling/en", if you have already created a custom dictionary for iWork, you will need to append this dictionary file to the end of your current custom dictionary. If you open it in a text editor (NOT a word processor) you can see the format for the file, I use BBEdit which also has an option to "view invisibles" non-printed characters (TextWrangler also has this feature). In the image below you can see on the left the Microsoft Word version in which every word is followed by the line feed character, ASCII 10 or line feed (LF), in the iWork version a red, upside-down question mark is used. A quick find and replace in BBEdit converts one format to the other.
You now need to copy and paste the reformatted contents of "Chemistry Dictionary" file into "en" and save it to "username/Library/Spelling/en". I'm not sure but you may need to log out and log back in again to get it to be used by all applications.
I've sent a zipped copy to the original author so it will be available as part of the distribution.This dictionary is obviously designed for use by chemists, in particular organic chemists and it would be really useful to extend this to other scientific or technical dictionaries. The conversion described here should also work for other dictionaries.