On April 14, 1849, the Flag of Our Union published Poe's tale "Von Kempelen and His Discovery." The timing is good because it continues the "hoax," the humor and, to a lesser extent, the science fiction aspects of the last post.
The tale begins by knocking down a Brunswick, Maine-based scientist who claims he made the same discovery before Von Kempelen. Poe doesn't believe it, saying that the newspaper reporting it probably made it up to "make a talk." After all, he says, it has an "amazingly moon-hoaxy-air" to it. That same hoaxiness is in the atmosphere of Poe's story too. As is typical, Poe adds just enough possible truth to it that it could be real — the original account of Von Kempelen's discovery was allegedly published in the Home Journal (a journal edited by Poe's friend Nathaniel Parker Willis) and Poe notes some possible errors in translation. In fact, the whole things sounds like a news piece (as intended), with the exception of being written in the first-person singular.
And Poe even seems to admit that he's writing another hoax! "There can be little question that most of the marvellous rumors afloat about this affair are pure inventions, entitled to about as much credit as the story of Aladdin's lamp." Yes, even this marvellous rumor that Poe is writing. He also notes (and a good Poeist catches this one easily) that Von Kempelen is related to a certain Maelzel.
In case you don't know, I don't want to hold you in suspense. What has Von Kempelen discovered? Why, he has been able to transmute lead into pure gold — "in fact, absolutely pure, virgin, without the slightest appreciable alloy!"
Sure, it seems silly today. But remember the story was published in 1849 — amidst the California Gold Rush. Poe was making fun of this sudden lust for gold (he'll note it in a more serious work, the excellent poem "Eldorado," as well). By the end of the story, we learn that Von Kempelen has been arrested and they are trying to force the secret out of him. In fact, people are so convinced that some day the ability to change lead into gold, that Europe already has seen "a rise of two hundred percent in the price of lead." This is comedy gold, certainly, as Poe notes that we choose what is valuable somewhat arbitrarily.