Many Greek recipes call for ammonia, especially cookies, bread sticks and crackers. This is a powdered form of ammonia used as a leavening agent. Ammonia powder is ground for baking purposes and is primarily used for baking cookies and puff pastries. During baking it will give off an aroma that will quickly disappear. The advantages to using this instead of another levener (baking soda or powder) are: it is heat activated, so it will not start to rise until whatever is being made goes into the oven, allowing for time to prepare without dealing with rising dough.