BRIDGMAN EXPERIMENTS WITH HIGH PRESSURES

Professor P. W. Bridgman '04 of the Jefferson Physical Laboratory has recently perfected an apparatus for achieving the highest pressures that have ever been artificially produced.

A Pressure as high as 600,000 pounds per square inch has been obtained. This corresponds, for example, to the pressure of an atmosphere 5000 miles high or an ocean 250 miles deep. An ordinary steam boiler has a pressure of some 400 pounds per square inch, and concrete collapses under 2000 pounds per square inch.

The conduct of materials under these pressures is of great interest. Steel is used as a lubricant in the apparatus, for oil becomes solid under compression. Four different types of lee have been discovered. Which freeze at different temperatures and pressures. Mercury dissolves in iron in the pressures. Mercury dissolves in iron in the pressure chamber of the pump.

The machine is worked purely by a hand pump, and is quite small, so small, in fact, that when some Dutch scientists were shown the arrangement, they asked. "But where is the machine?" On, various occasions Professor Bridgman has just missed losing a limb when the apparatus emploded, for the pressures seem to burst easily an inch thick wall of hardest metal. Professor Bridgman is still perfecting the arrangement and hopes to achieve pressures of 800,000 pounds per souare inch or even higher.