Nitrogen
From Captain of Industry Wiki
Nitrogen is a gaseous chemical element, typically produced as a byproduct of using Air Separators to produce more valuable Oxygen. Its only use is in the production of Ammonia, but it is rarely used for that, as Ammonia in a plentiful byproduct of Sour Water processing.
Nitrogen is harmless to release into the atmosphere via Smoke Stack.
Recipes
Below are all the recipes which contain this item. Note that some of them may be locked behind Research and not immediately available in your game.
Production