Smells like science!

From "Hearth Surgery: The quest for a stove that can save the world" by Burkhard Bilger, filed under "Annals of Invention" in the December 21 & 28 2009 double issue of the New Yorker magazine:

In seventeenth-century England, when a stovemaker wanted to test a new design, he'd soak a piece of coal in cat's urine and throw it on the fire. If the stench went up the chimney with the smoke, the design was deemed a success.