Google doesn't know that word, philogiston.
In confronting this mystery, I attempted to look it up but kept getting phlogiston, "a theory postulating the existence of a fire-like element dubbed phlogiston, contained within combustible bodies." Doesn't sound like it would fit the context of Spelling Bee. Could this be one of those once in a decade (at most!) New Yorker copy editing failures??!
Then I tried philologist and found "a person who studies the history of languages, particularly through the analysis of literature," which seemed more likely, so it could be a misspelling or some kind of wordplay, since McPhee talks about "igniting" it.
But I looked up the article online and it said phlogiston. One of those situations where a misspelling in print is fixed online (as I had to do the other day when a snarky reader emailed to say I'd misspelled "dentil molding" as "dental" -- hey, it looks like a row of teeth! -- so we changed it online and luckily it hadn't gone to print yet).
But then I looked in the print version in the magazine, which finally arrived yesterday. It does say phlogiston.
Hey, McPhee, read your ... oh wait, I was going to say read your Strunk & White, but I found a copy of
Elements of Style online and it doesn't have a rule against using big fancy words.
But then I remembered who does: Mark Twain! ?Don't use a five-dollar word when a fifty-cent word will do.? Twain's quote may be less of an ironclad law than something you'd find in Strunk & White, but I will say reporters follow rules like never say "utilized," say "used."