`Incandescent light bulb development (Edison/Langmuir)`

Used to introduce the Langmuir as a unit of contamination time. Edison's carbonized horsehair filaments → tungsten in argon → factor-of-100 longer life from suppressing evaporation.

There's a guy, Irving Langmuir, who won the Nobel Prize working for General Electric. Edison had invented the incandescent light bulb, but they didn't last very long — less than 10 hours, which was getting kind of pricey. Anybody know what material Edison used before tungsten? Carbonized horsehair. He'd carbonize the hair, end up with a graphite filament. The carbonized horsehair might last an hour before it would vaporize. They learned tungsten would last longer.