While the exact discovery of ammonia is debated, it's generally attributed to Joseph Priestley in 1774. He produced ammonia by heating ammonium chloride with lime.

However, it's important to note that:

* Ancient civilizations were likely aware of ammonia due to its presence in animal waste and the use of ammonium salts in dyeing.

* Carl Wilhelm Scheele also independently produced ammonia around the same time as Priestley.

So, while Priestley is often credited with the discovery, it's more accurate to say that he was the first to isolate and characterize ammonia.