Atmospheric pressure

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A 2010 Groton School experiment in which a few inches of water is put into a 55 gallon steel drum, which is then heated from the bottom, using a propane flame, until steam forcibly is seen leaving the vent hole. The vent hole was is then sealed, and the drum was put into a tub of ice water, and sprayed on top with hose, crushing inward in about 60 seconds, owing to atmospheric pressure, i.e. pressure of the surrounding air of the earth, with respect to the reduced pressure inside of the drum, when the vacuum is made inside.[1]

In terms, atmospheric pressure (CR:5) (LH:1) (TL:6) is the force per unit area of the volume or mass of air surrounding the earth pressing down on the surface or given altitude of the earth, which decreases with increase in altitude, becoming zero at the Karman line (61 miles above the earth's surface), wherein outer space begins.

Overview

In 1614, Isaac Beeckman, in his journal notes, according to William Middleton (1964), had correctly explained the action of a suction pump by an appeal to the pressure of air, and compared air to a sponge, which can be condensed, but because of its elasticity tries to return to its previous state.

Guericke

In c.1648, Otto Guericke, in his second vacuum experiment, had two men suck the air out of a 65 quart sealed copper sphere[2], as shown below, using Guericke's recently invented vacuum pump:

Guericke second vacuum experiment.png

When the two men got to a certain point, wherein the majority of the air had been sucked out, the aim being to make a "vacuum" or void inside of the globe, the entire globe collapsed like a cloth crushed in one's had to a loud noise:

“While they were engaged in plunging the piston rod in and pulling it out and began to feel confident that essentially all the air had been extracted, suddenly, and to the terror of all, with a loud report, the copper globe collapsed like a cloth crushed in one's hand or as if the globe had been hurled from a tall tower and had landed with great force.”
Otto Guericke (1648), “On Second Vacuum Experiment Performed Through the Extraction of Air”; in: New Magdeburg Experiments on the Vacuum (pg. 115-17)[3]

This was the first demonstration of the weight of the atmospheric pressure. A video example of steel drum being crushed by atmospheric pressure when a vacuum is made inside its volume is shown in the adjacent video.[1]

Papin

Diagrams of the Papin engine, Savery engine, and the Groton vacuum drum experiment, shown in video[1]

In 1690, Denis Papin, in his Papin engine, suggested that a vacuum could be made by putting water inside of a piston and cylinder, first heating it until the water is turned to steam, then cooling the steam by spraying cold water on the outside, so to make the vacuum, which would thus force the piston down, owing to atmospheric pressure.

In c.1700, the Papin engine model, in respect to spraying the condensing chamber, on the outside with cold water, so to make the vacuum, was realized in the operational Savery engine.[4]

Here we see the Papin-Savery model of spraying the outside of the system or volume, i.e. piston and cylinder (Papin, 1690), condensing chamber (Savery, 1700), or steel drum (Groton, 2010), containing steam within as the working body, causes heat to move from the working body to the cold body (tub of ice and spraying hose water), actuating a phase change from steam to liquid water in the working body, thereby making a vacuum inside of the volume (or system), which has a internal pressure PI far less than the surrounding pressure or atmospheric pressure PA, at the surface of the earth:

which means that he force of the surrounding atmosphere pushes inward on the system and crushes the 55-gallon steel drum, as shown above or moves the piston head down, in the Papin engine.

Quotes

The following are related quotes:

“If you remove the obstacle which prevents the local movement of a stationary body, it will be shifted. If by sudden rarefaction you get rid of the air which surrounds the enormous trunk of this oak tree, then the water it contains will suddenly expand and blow it up into a hundred thousand fragments. I’m saying the same thing is true for your own body.”
Denis Diderot (1769), Alembert’s Dream (§1.12, character: Diderot)

End matter

References

  1. 1.0 1.1 1.2 Anon. (2010). “Steel Drum Crushed by Atmosphere Like Pop Can” (YT), Groton School, The Chem Man; Human Chemistry 101, 2021, Jun 3.
  2. Schott diagrams – Hmolpedia 2020.
  3. Guericke, Otto. (1663). New Magdeburg Experiments: on the Vacuum of Space (Ottonis de Guericke Experimenta Nova (ut vocantur) Magdeburgica de Vacuo Spatio) (translator and preface: Margaret Ames) (pg. 117). Publisher, 1672; Kluwer, 1994; Springer, 2012.
  4. Thims, Libb. (65AE). Human Chemical Thermodynamics (pdf) (§17: Savery). Publisher.

External links

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