Here's why these names were used:

* Sulfur: This was the most common name used, directly derived from the Latin word "sulphur". It was recognized as a distinct element with its own unique properties.

* Brimstone: This term, which comes from Old English, carries the meaning of "burning stone" and reflects sulfur's ability to burn with a bright blue flame and produce a pungent, choking sulfur dioxide gas.

* The Stone: This term was a more esoteric one, used by alchemists to refer to sulfur as one of the three "philosophical principles" (along with mercury and salt) believed to be essential components of all matter. It was seen as the principle of combustibility and the source of heat and energy within the universe.

So, depending on the context, an alchemist might have referred to sulfur by any of these names, each carrying its own specific connotation.