If Ivory Soap is 99 and 44/100% pure, what’s the other 56/100%?

Illustration by Slug Signorino

Cecil replies:

I don’t know that our primary concern ought to be the 56/100ths, Peter. As a legendary economics professor once put it, the real question is, “99 and 44/100% pure what?” Since you asked, however, the remainder consists of foreign and unnecessary substances.” Bear with me a second and I’ll give you the results from the lab.

It all started in 1881 when Harley Procter, son of Procter & Gamble co-founder William Procter and a legendary soap salesman in his own right, decided he needed a new angle to hawk Ivory soap. Then as now people were impressed by scientific testimonials, and Harley decided if he could come up with a lab test showing Ivory was “purer” than other soaps, he’d win sales.

Trouble was, there wasn’t a standard for purity in soap, so Harley hired an independent scientific consultant in New York to concoct one. The consultant concluded that a 100% pure soap would consist of nothing but fatty acids and alkali. You see now why the Ivory slogan is so cryptic. If you announce to the world that what you’re selling is “99 and 44/100% fatty acids and alkali,” you’re not going to sell a lot of soap.

A definition of purity having been arrived at, Harley sent out some Ivory Soap for analysis and compared it with earlier analyses he’d had done of castile soap, regarded at the time as the best soap available. He was gratified to discover that by his consultant’s definition, Ivory soap was purer than the castile soaps. The impurities consisted of uncombined alkali, 0.11%; carbonates, 0.28%; and mineral matter, 0.17%. Total: 0.56%. Thinking that “99 and 44/100% pure” had just the right touch of technical authenticity to appeal to the great unwashed, so to speak, Harley began sticking the phrase in Ivory advertisements, and another classic marketing slogan was born.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.