Where did the idiom “That’s gas” originate?

I often say 'That's gas' to refer to something that I found humorous.

I have looked to find how it originated but could not locate. Is anybody aware of its history?

It’s probably a variant of the old expression It’s a gas which ultimately referred to the discovery of nitrous oxide and its power to give euphoria to those who inhaled it:

Scientist Humphrey Davy noticed that nitrous oxide produced a state of induced euphoria which led to laughter followed by a state of stupor and, finally, a dreamy and sedated state. Seeing no harm in the use of the gas, he introduced nitrous oxide to the British upper class as a recreational drug in 1799 at gatherings that were quickly coined “laughing parties.

At these “laughing parties” guests would take a whiff of nitrous oxide and then throw themselves in what were referred to as “nitrous oxide capers.” These capers led guests to stumbling about, slurring their speech and falling down. Davy noted that some people at these “laughing parties” found themselves in a state of induced euphoria due to the gas.

It didn’t take long for the term “it’s a gas” to become a sort of code for what one could expect if they attended a certain British upper class gathering.

It wouldn’t be until 1835 that nitrous oxide would be used medically but by then, the term “laughing gas” had stuck even with medical professionals.

While the “laughing parties” and “nitrous oxide capers” are things of the past, the term “it’s a gas” continues to imply that the event or activity is sure to amuse and bring gales of laughter to those attending the event or participating in the activity.

(Historically Speaking)