Ivory soap claims to be "99 44/100%” pure. Pure what exactly? 99 44/100% exactly. On December 14, 1882, the chemist W. M. Habirshaw sent Harley Procter a sheet of numbers that refused to round cleanly. The bar measured 72.53 percent fatty anhydrides, 9.28 percent combined soda, and 17.63 percent water. Those three columns added to 99.44 percent. The leftover 0.56 percent sat in smaller lines: 0.11 percent uncombined alkali, 0.28 percent carbonates, and 0.17 percent mineral matter from the ordinary run of the factory. Procter kept every digit. He put the full decimal into the next advertisement rather than the smoother hundred he could have written. At that moment the trade still had no rule for what counted as pure soap, and many bars carried clay, gypsum, or extra water simply to fill the mold. The figure Procter printed recorded only what Habirshaw had weighed in that single sample. The advertisement carrying the number appeared the following week.