153Evaluating Critical Parameters in the Process
In 1878, the Procter & Gamble Company perfected a new bar soap formula
called “White Soap.” This product had a pure white color, because the manu-
facturing process removed impurities common in soaps of that period. The
product was successful as an incremental improvement.
One day in 1879, customers came to the company raving about a batch
of the product that excited them. These bars of soap oated, making them
easier to nd and use in the bath. According to legend, it was discovered that
this batch of product had been left in the mixer for too long. A froth of tiny
air bubbles had become entrained in the product and remained there while
it solidied. The resulting bars had a lower bulk densi