These jolly, elfin skeletons come from a 1900 calendar put out by the Antikamnia Chemical Company, makers of the early pain reliever Antifebrin. The skeletons may seem a little disturbing, but there's nothing to worry about... except for the tiny detail that Antifebrin stops the flow of oxygen to the blood.
Remarkably, the skeletons up top are actually reasonable pleasant, at least as far as Antikamnia's skeleton mascots go. You can check out the complete set of calendars over at Retronaut, but just check out the terrifying fellow on the left from March/April 1899. I realize the "For Pain" sign on the right is meant to tell you what Antifebrin relieves, but given the fact that it was potentially fatally toxic, it's kind of hard to read that as anything other than what Antifebrin causes, or possibly even as the skeleton's position statement — you know, he's in favor of pain, just as a matter of policy. The sign on the bottom about how it's "HIS fourth of July!" is also a bit worrying, as though this hellish undead pain beast has stolen one of America's most cherished holidays, or perhaps even declared his terrifying independence from our living human oppression.
My paranoid fantasies aside, there's still the story of the toxic drug Antifebrin, which got the Antikamnia Chemical Company shut down for failing to disclose that its active ingredient was acetanilide, which even then was known for its toxic effect on red blood cells. Here's the rest of the story, courtesy of It's Okay To Be Smart:
But Anitkamnia was an effective pain reliever, even if you'd go blue after taking it. One thing many people don't realize about pharmaceutical chemicals is that they are metabolized and modified by human biochmistry. For many of them, the compound in the pill is useless, and they require breakdown or modification to become active. It wasn't until nearly half a century later that Nobel Prize-winning biochemist Julius Axelrod discovered that the primary metabolic product of acetanlilide is a compound called paracetamol.
Paracetamol, of course, is now one of the world's most popular pain relievers — although I'm an ibuprofen man myself, truth be told — and is better known in the United States as good old Tylenol.