[1] https://www.catholicnewsagency.com/news/263867/the-story-beh...
> The addition of the white smoke to announce the election of a new pope is more recent, however. Baumgartner traces it to 1914 [...]
but also
> In ancient times, the method to give the smoke these colors was to burn the ballots used in the voting with a bit of wet straw [...]
In ... the ancient times of 1914? Something's wrong here.
(For what it's worth, the Wikipedia article about this says that before 1914 black smoke meant "we held a ballot but it didn't successfully choose a new pope" and no smoke meant something other than that, though it's not clear there what the "we got one" signal was. The Wikipedia article, unlike the Catholic News Agency one, cites some references, but I haven't checked them.)
The whole black smoke/no smoke didn’t start out as a signal but everyone kept trying to interpret them as such in the 19th century. Black smoke meant no election and no smoke was ambiguous so they eventually switched to white smoke to keep the public from going crazy speculating. L
The first reference to non-black smoke I can find is in "Conclave di Leone XIII" by Raffaele De Cesare about the 1878 conclave (Leo XIII’s election):
> "Cardinal Borromeo, tasked with burning the ballots, burned them without straw, and the smoke was barely visible. There were few people in the square. The external steps of St. Peter's were full of onlookers until midday, but after the smoke, it slowly emptied. No one supposed that the Pope had been elected." (translated from Italian)
The 1914 conclave is the commonly accepted date because Pius X decreed in 1904 that all papers relating to the election (not just the ballots themselves) were to be burned after the voting. Since they’d burn all the others papers (without wet straw) only after a successful election, it would produce a lot more white smoke so the Catholic church made an administrative decision to make that into an explicit signal (though I think they use something to “enrich” the color now).