Melting the Unmeltable

There are many ways to melt metal, but an arc furnace can liquefy almost anything you put in it, using only electricity.

By Theodore Gray | Published May 1, 2004 10:00 PM

Dept: Gray Matter

Element: Tungsten

Project: Arc melting

Cost: $220

Time: 30 minutes

About a century ago, having no television for entertainment, a famous French chemist named Henri Moissan decided to see what would happen if he stuck two carbon-graphite electrodes into an insulated box and ran a lot of electric current through them. He figured if he trapped and concentrated the heat produced by the arc he struck, he might be able to do something neat with it. (Yes, scientists get paid for thoughts like these.)

Moissan’s hunch was right–boy, was it right. He quickly found that with temperatures reaching 5,000

After

The silica walls of the still-glowing furnace have begun to liquefy and drip down.

During

The viewing port allows you to see in to steer the arc around with the electrode handles.

Before

With the lid removed you can see the two quarter-inch copper-clad carbon electrodes and the graphite crucible holding some broken-up tungsten rod.