Which anaesthetic was known to catch fire and had a vile smell?

Ether was known for its distinguishing characteristics, which included a highly flammable nature and a notoriously unpleasant odor. It was among the first anesthetic agents widely used in surgery during the 19th century. While ether was effective for inducing anesthesia, its volatility posed significant risks. The presence of oxygen and a spark could easily ignite ether, leading to fire hazards in surgical settings.

In contrast, chloroform, although it had a sweet smell and was less flammable, did not have the same notorious reputation for catching fire, while nitrous oxide is a gas used primarily for pain relief and sedation, and acetone is rarely associated with anesthesia in historical contexts. Therefore, ether stands out as the correct answer for this question, highlighting both its positive effects in surgery and the challenges posed by its properties.