Science at the Priestley House

The house was designed so that it had a few chimneys, including an area with 2 furnaces where Joseph Priestley built his laboratory. At the time of my visit, we were treated to a demonstration on his discovery of oxygen. It starts like this. His wife had tuberculosis, and over the course of his studies on matter he had noticed that if one put chalk in a test tube and added an acidic solution to it, the solution would bubble. He tried putting a lit match into the test tube, and it extinguished itself. chemistry At the time, there was Aristotle’s division of the natural world into water, air, earth, and fire. No one had yet really understood anything about different kinds of air.  So, he kept at it, putting first one compound, then another in various test tubes, adding water or other solutions, sometimes heating them, looking for bubbles, and testing what came out with a match.  Sometimes, the match went out.  Sometimes, the match burned more strongly.  Sometimes, even, he would put a glowing extinguished match in, and the match would light back up again.  It was like extracting air from water, extracting fire from air, the dead coming back to life!  There could be no doubt that the air that was being produced in the test tubes was different depending on what compound was used.

Was it dangerous?

At this point, things get a little squeamish for someone who loves animals.  We’ll assume a little mouse volunteered to be the canary in the coal mine…  Priestly extracted the gas from the test tube using a rubber tube (rubber also was discovered in America), passed it through a water solution to verify that bubbles were happening, and then into a overturned glass container where he had placed the mouse.  He at first observed that the mouse would start to show signs of distress when she began running out of air under the glass, at which point, he would open the container.

So, he measured the amount of time before the mouse began trying to get out with the various gases he had produced in the test tubes.  The one with chalk, that put out the flame, caused the mouse to seek escape more quickly.  The one with the compound, that caused the flame to reignite from its extinguished state caused the mouse to actually look a lot better and happier.  Since, Priestley did not know anything about oxygen, he simply called this last one dephlogisticated air.

Maybe he had discovered a cure to help his wife breathe better.

He tested it first on himself, and then decided that he did in fact feel better, so that he might try giving the gas to his wife.  At which point, the mouse, her job done, hopefully went into retirement with lots of freedom, bread, cheese and milk, and the wife lived a little longer. He has a long list of publications.

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