homeWelcome, sign in or click here to subscribe.login
     


 

 

Weekend


Subscriber content preview

January 7, 2011

Strange But True!

Q. As any seasoned cook knows, a quick sprinkle of water on a skillet can tell if it's hot enough, as the drops bead up and dance about on a thin cushion of water vapor. What's the name for this remarkable phenomenon?

A. It's the “Leidenfrost effect,” after Johann Gottlieb Leidenfrost, who studied it in 1756, says Jearl Walker in “The Flying Circus of Physics.” This is what keeps the drops from sizzling away immediately, telltale sign the skillet isn't yet hot enough. The thin-cushion Leidenfrost effect also comes into play when barefoot firewalkers daringly step across glowing hot coals. The sweat on the nervous walker's feet may vaporize to form a sort of protective layer, with other factors helping as well.


 
. . .


To read this story in full login or purchase a subscription.



Previous columns:



Email or user name:
Password:
 
Forgot password? Click here.