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Raising boiling point of salt water

  1. Apr 11, 2009 #1
    How much salt per quart does it take to raise the temperature of water to 325 degrees at 28 PSI?

    I am sorry to say I am not educated in physics but I do understand the more particles in the water the higher the boiling point. I am trying to plasticize animal horns in a pressure cooker with a maximum pressure of 28 psi.

    Thank you for making this kitchen table ready !


  2. jcsd
  3. Apr 12, 2009 #2


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    Answer: No amount. Look at a Dühring plot; saturating water with NaCl only raises its boiling point by about 10 degrees C. You can't get up to 325 F without pressures substantially larger than 28 psi.

    Then there's also a quite obvious concern about having highly pressurized boiling water around, and using pressure cookers in ways they're not intended.

    Why not just use oil instead?
  4. Apr 12, 2009 #3
    Thanks, for the prompt reply. The dilema is not to cook the horn by using direct heat. I am concerned about the horn becoming brittle. I know it is possible to soften the solid tip deep enough to straighten it sufficiently to drill and form a mouthpiece.

    The particular pressure cooker I am using has two saftey devices integral to keep it safe. One is set at 28 lbs PSI, the other is at 40 PSI, (and is not mechanical but a failure point of a rubber plug in case the first fails). The tank itself can go much higher, well over 100 psi without failure. I contacted the design department first to make sure I was not in danger.

    Not sure if food safe glycerin would work?

    Are there other ways to create moist heat above 300 degrees? I thought about super heating steam.

    Any help would be appreciated. The horn is keratin much like a tough fingernail.

  5. Apr 12, 2009 #4


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    That'd work. It's got a boiling point well over 300 (554 F). If you must have some water in it, you could add about 5-10% water (by weight) and get a boiling point at about 300 degrees at atmospheric pressure, according to http://www.dow.com/glycerine/resources/table16_91100.htm" [Broken]. Should be fairly easy to test yourself, on a stove with a thermometer.

    Yeah well that's what you'd need with just water or water/salt. Most autoclaves don't go that high even (and if you've seen one, they're a lot sturdier than a pressure cooker.) I'd strongly recommend against working at elevated pressures. Worst case scenario doing it the first way is a spill, worst case the latter way means an explosion.
    Last edited by a moderator: May 4, 2017
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