Determining the Barometric Pressure without a Barometer


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Here are two photos of a tank car that collapsed under ordinary air pressure — emphasizing the importance of the barometric pressure!  The exact explanation is not known to this writer, however, there two plausible possibilities come to mind: (1) A sealed tanker may have contained a gas that condenses to liquid when it gets cold (for example, sulfur dioxide, bp –10 oC).  If the tanker contained liquid sulfur dioxide which was then drained and sealed, the tanker would contain sulfur dioxide vapors that would condense to a liquid if the temperature dropped below –10 oC; or (2) If water were added to a tanker containing a water-soluble gas under conditions whereby air could not enter the tanker fast enough to equilibrate the pressure inside the tanker with the atmospheric pressure, the tanker could collapse.  This could happen if the water were added via a hose threaded to the tanker creating a “closed system” in terms of air pressure.  See the ammonia fountain experiment. 

crushed tank car

crushed tank car 2