Re: rod-mill project - "mains" electric motor advice

"Richard Smith"  wrote in message news:m1pleup761.fsf@void.com...
"Jim Wilkins" <muratlanne@gmail.com> writes:

...

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How did you/they determine the amount of lead?
>
In first year chemistry we learned qualitative but not quantitative
analysis.
Some of the most useful chemicals for analysis are now restricted as
hazardous.

Put it on a weighing scale.
57grammes
From 100g of the gelana concentrate.
It looked like lead and had a lot of density.
No assay of the metal yet.
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The lead may contain other similar metals such as tin, bismuth and antimony, cupellation should have left any silver as an undissolved bead. What was the cupel made from?
I suppose for a show-and-tell museum display the more tedious aspects of traditional chemical analysis would be wasted, except for the few like me who annoy the presenter with questions they can't answer.
Galena was the Crystal in early radios. It forms a Schottky barrier diode where the metal whisker contacts it.
https://en.wikipedia.org/wiki/Crystal_detector
https://people.ohio.edu/postr/bapix/CrystlRd.htm
https://www.homemade-circuits.com/point-contact-diodes-history-construction-application-circuit/
Similar Germanium contact diodes with metal spring ribbons were used through the 1950's and later. Early US rocket launch failures eventually were traced to the ribbon vibrating out of contact, the noise level in the rocket is around 160 dB. Google didn’t find much on it, I learned in person from a rocket scientist, and also about the moon landing "computer failure" false alarm.