APPARATUS GIVES PRESSURE OF 600,000 LBS. TO SQUARE INCH

Manawatu Times, Volume LIV, Issue 6815, 19 January 1929, Page 7

APPARATUS GIVES PRESSURE OF 600,000 LBS. TO SQUARE INCH

Highest Ever Produced

Inventor hopes TO SURPASS POINT

Working with an apparatus of his Own invention, Percy W. Bridgman, Harvard professor, has attained an artificial pressure of 600,000 pounds per square inch, by far the highest ever

produced, and now expects to surpass this point.

This pressure, it was explained, 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, it was stated. The invention is already in use in the manufacture of big guns and other commercial applications are either being made or anticipated. In the laboratory, however, Professor Bridgman uses the apparatus in studying materials and the change made in their molecular and atomic makeup under such a weight. When placed under pressure varying between 200,000 and 600,000 pounds per square inch, it was declared, paraffin becomes harder than machine steel, and

rubber becomes so hard that it may be used as a die to form steel. Pour different kinds of ice were discovered, forming at different pressures. The impossibility of using oil as a lubricant in the process was soon found it was said, 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, it was shown, this 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.