That was some good google-fu
. Actually, your dimensional drawing was the clue, that made me look for 12 mm cartridges, which let me to the Scheintod cartridges which led to the pictures. Unfortunately I haven't found out yet what the gas load was.
It's really funny, it gives you instructions on how to "experience" your own gas (the top part of the inside box). Short version: Fire inside room and immediately run into the gas cloud.
Somehow I don't think that that method would go past legal review in today's marketing.
It suggests to not shoot at friends.
Found this
page that suggests that the cartridge was originally loaded with powdered tobacco, and later with CS.
It must have been common enough that
US postal regulations forbade the import via mail
And I found the truly suicidal hint that it chambers a 44 Magnum very nicely...