Metallurgist is trying out all kinds of steels looking for a particular attribute. He would dutifully record each recipe + test in a notebook but if a particular batch didn't have the attribute, he would throw it out a window into an outdoor scrap pile.
Several months go by and he's cleaning up the pile and notices that one of the blocks has no rust or corrosion. He knows that the pile is six months old but doesn't know which of the recipes this block was connected to.
So he repeats ALL of the block recipes from the last 6 months but labels each block so he can figure out which recipe led to the "stainless" steel.
(Probably not the real story but always loved this telling of it. Actual Wikipedia history is here: https://en.wikipedia.org/wiki/Stainless_steel#History)