NEW YORK (CNN/Money) - The Loch Ness Monster isn't real. Elvis really is dead. Oswald acted alone. ... And Ivory Soap doesn't float by accident.

Yes, debate will probably rage on about the first three, but the Ivory Soap legend, well, that's going to be put to rest.

Procter & Gamble folklore, repeated in the brand history on the company's Web site, has it that Ivory Soap's buoyancy was a mistake. An employee mixing the first batch in 1879 decided to go to lunch, the tale goes, and absent-mindedly left the soap mixing machine on. By the time he came back, the mixture had been thoroughly laced with air. The shipment went out nonetheless. Later, customers wrote in asking for more of that "floating soap." Hey, in the spirit of "give'em what they want" the company whipped air into the soap from then on.

Sure is cute, but it turns out the legend is wrong -- or at least very, very suspect.

Researchers combing through company records for a book coming out in July discovered a 1863 entry in a diary kept by James N. Gamble, son of the company co-founder and the chemist in charge of soap making. The entry: "I made floating soap today. I think we'll make all of our stock that way."

Aha!

"It was not an accidental discovery," said Ed Rider, P&G archivist. "Whether or not it was intended for Ivory, though, remains a mystery."

In those days of wash tubs and hand washing, though, that Ivory could float was a good selling point. "If you took your bath in the Ohio River, it made it a lot easier to find your soap," Rider pointed out.

The new book, "Rising Tide," is a collection of 14 case studies on various P&G products and will lay out the debunking of the Ivory Soap floatation myth.

But Rider said it won't address one of the more interesting Ivory Soap stories.

That would be the one involving the 1972 Ivory Snow box featuring a young mother and a baby. The model portraying the young mother, Marilyn Chambers, went on to star in the porn classic "Behind the Green Door." Procter & Gamble was horrified, dropped the campaign, and started learning the value of morality clauses in modeling contracts. Marilyn Chambers went on to become a porn superstar.

While we're clearing up fact and fiction around Ivory Snow, Chambers was the mother on the Ivory Soap box -- not the baby, as urban legend had it. To see the evidence, check with the professional debunkers at Snopes.

Now another legend I've heard is that all of Chambers' films feature a reference to Ivory Snow in some way. But I wouldn't know.  

Allen Wastler is Managing Editor of CNN/Money and a commentator on CNNfn.