RECORD PRESSURE ATTAINED

Dominion, Volume 22, Issue 186, 4 May 1929, Page 29

RECORD PRESSURE ATTAINED

Working with an apparatus of his own invention, Professor Percy .W. Bridgman, of Harvard University, has attained an artificial pressure of 600,0001 b. a square inch ,by far the highest ever produced, and now he expects to surpass this point.

This pressure, it is explained by a writer in the “Christian Science Monitor,” corresponds to what it would be at the bottom of an ocean 250 miles deep. Under such a push, steel tends to flow, if not like water, at least enough to spread. The invention is already in use in the manufacture of large guns and other commercial applications are either being made' or are anticipated. When placed under pressure varying between 200,000 and 600,0001 b. a square inch paraffin becomes harder than machine steel, and rubber becomes so hard that it may be used as a die to form steel. Four different kinds of ice have been discovered, forming at different pressures. The impossibility of using oil as a lubricant in the process was soon found,

for the liquid became a solid under compression. Nor could mercury be compressed beyond a pressure of 60,000 pounds, because its atoms worked in between the atoms of the steel holding it, practically dissolving in the steel. The apparatus used is comparatively simple. A small and most ordinary appearing hand-pump provides the air for pressure. The material to be compressed is held in a small hole bored, in a solid piece of steel five inches thick. This, in turn, is stopped with a small steel plug. Under pressure thip plug flows or spreads, preventing escape .of the substance being pressed and making the invention possible. As might be expected, work at this pressure is not without incident. A wire enters the steel chamber as an aid to measuring pressure. Back of this wire is a half-inch armour plate, plentifully dented where the wire has been shot out, propelled by tremendous force. Professor Bridgman testifies that on one explosion of the almost solid steel compression chamber itself fragments penetrated six inches of hard pine planking.