When I was in 9th-grade jhs, I performed a similar experiment in my science class. Nobody had a clue back then (1968) of what 'borax' was or where to get it. I substituted boraxo hand soap. For the experiment to work, it took a huge amount. I didn't use an oscilloscope back in that day. I remember rigging some kind of polarity detector using an incandescent lamp (probably a #222), and a couple of cheap silicon diodes from Radio Shack. For electrodes, which were inteneded as lead and aluminum, I used some sheet aluminum my dad kept around for some of his projects, and for the lead, I used a length of 50% lead 50% tin solid wire (no flux core) plumbing solder. I used a pint-sized mason jar, a mason ring, and cut a top for the jar from some thin cork I had. I may have used some cheap binding posts to suspenmd the electrodes from. I made the test right after lunch, say 1:00pm, and proved rectification with a 10-volt drop through the rectifier. After school, say 3:00 pm, the schools Science club, of which I was a memeber, convened in that room for a regular meeting. I attempted top repeat the experiment, and it failed: my rectifier wouldn't conduct anything in any direction. The Boraxo seemed to have 'gelled' in the jar and had turned pink. I ended up disposing of all the 'mess'. I never repeated the experiment.
"I have observed an interesting N type negative resistance effect that happens only when the tip of a very sharp aluminum electrode is just barely touching the top surface of the solution."
What exactly does negative resistance mean in this context? Based on the curve shown I would guess as the voltage increases past a point the resistance decreases. But it is fun to imagine this guy has discovered perpetual energy.
> This opens up another very fasciniting [sic] possibility. A cell with two adjustable aluminum plates (a variable capacitor) might very well be useable as an efficient light dimmer.
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