Resistivity of amalgams still a mystery



Oh. So you weren't serious when you wrote in message
that you were going to "apply it to non-ideal, or non-typical conditions which would exist in practice" ?

Sure. "A function of" covers almost anything.

Not when you try to "apply it to non-ideal, or non-typical conditions which would exist in practice".

Quite. Have you considered that the changes might not even have the same sign?

Interesting assumptions. Can you justify them? And don't you want some decay rate constants in there?

With the stated assumptions, it's a power law. With different assumptions it would be something else.

Sure. Anything you say. But I know the difference between correlation and causality. "Both vary with time" says nothing significant about their relationship.

Did you?
--
Richard Herring

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Richard Herring wrote:

I can postulate any theoretical relationship I want. You don't make the rules.

Have you considered that it wouldn't matter because the total resistance of the amalgam would still be a function of time. I don't know what you are getting at but you should be able to understand that as an amalgam loses Hg the rate of vaporizaton will change as well the structure of the amalgam itself changes leading to changes in resistance. In other words, as the amalgam becomes "less dense" by losing Hg, the rate of vapor emission and resistance will change. I don't really give two cents whether the changes are large or even measurable. I only stated that a relationship exists with is worth understanding, because, if you can theoretically predict the change in resistance as a funtion of rate of vaporization, you can (although I know this is years away) theoretically predict the rate of Hg loss from the amalgam under all circumstances.

Dosen't every equation having to do with circuits and solid state end up being e to the something or other? (and it does seem to fit the bill since the vaporization slowly decreases but never goes to 0)

sure
measure it. Put an amalgam in a circuit next to an Hg vapor meter, and measure the change in the total resistance of the amalgam and rate of change of vaporization as a function of time.

The point is that more research should be done to understand the relationship of all the physical properties of amalgam. If you want to derive a full blown solid state theory of Hg vaporization from amalgam go ahead. (I know that no current theory comes close to being able to do this).
Since you appear to have some science background you should agree that the amount of remaining Hg in the amalgam would directly affect the rate of vaporization and the resistance to some degree, establishing the "causality". No aristotilian reflection on the nature of correlation and existence is required.
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wrote:

So far you have shown knowledge in a limited area. If you have electrical engineering experience, you should know enough not to target resistivity per se.
I can think of some tests but the probability of detecting any signal that is of a level to do any harm is pretty well zilch. Possibly an amalgum can be used in place of the "crystal" in a crystal set- but where is the tuning LC circuit and the antenna to receive sufficient signal? Now you have do deal with the tooth signal reaching an auditory nerve. There are reports that it occurs but proving that is not a simple task. I suggest that you build an old fashioned crystal set using a "cats whisker" and an amalgam "crystal. If you get anything with that, then do some more playing about. Noting that any such pickup of signals is rare it might be extremely difficult to find the combination of conditions that lead to such sensitivity. Following that you could put a subject in a screened room along with a modulated RF source (test across the normal AM band and modulate with some definite signal of your choice) and determine if the subject can (a) sense a signal and (b) tell correctly whether the source is on or off.
Obviously this is not something that you can find in the journals, either dental or electrical. Possibly, as I indicated before, this is not a significant problem in either field.
--

Don Kelly snipped-for-privacy@shawcross.ca
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Don Kelly wrote:

What was interesting to me, not that I had any problems, was the electrolytic action between an amalgam filling and a steel backed crown - 80-100mV into 1 megohm.Has any work been done on that kind of effect ?
Steve
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That's funny.
Some years ago under the newsgroup thread "Dental Amalgam and the Absorption of Electromagnetic Energy", professor Harvey Rutt, the Deputy Director of the School of Electronics & Computer Science at the University of Southampton in the UK told me:
"About the only relevant property is the resistivity."
Would you suggest that Professor Rutt was mistaken?
Also, until recently the website of electronic equipment manufacturer Gore Electronics used to make the following assertion regarding the electromagnetic properties of materials*:
"If you can describe the permittivity, permeability and conductivity of a material, you can describe completely how electromagnetic energy behaves within that material."
I'm sure I don't need to explain to you the relationship between conductivity and resistivity. However I am beginning to wonder if you yourself understand this subject as well as you might.
Keith P Walsh
* If I were the "conspiracy theory" type I might wonder if Gore Electronics had been persuaded to remove this statement from its website by someone not purporting to represent the interests of the dental profession.
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When you put it in the context of tiny bits of metal in a mouth, no, because the likelyhood of any RF effects, unless you stick your head in a microwave oven, where permittivity and permeability become important are somewhere between nil and not at all.
But that just ignores the biggest part of you lunacy.
First you have to establish as fact that very low level electricity in the mouth is harmfull in some way and then determine the harmfull level.
If and when you do that, then you can ask the question is an amalam filling capable of generating a harmfull level.
Of course, you are totally ignoring all the other metal things that are used in dentistry, but that's only because you are obsessed.
<snip babble>
--
Jim Pennino

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wrote:

So I disagree with Prof. Rutt (except that the teeny bit of energy dissipated in the amalgam would depend on resistivity although the other factors would affect the delivery of the energy). Note: Gore electronics mentions permittivity and permeability before resistivity. Possibly the statement was pulled because it was considered a trite truism.
My previous comments hold.
Dammit, see what a mistake the University of Illinois made in giving me a PhD in Electrical Engineering! Possibly I know enough to know my limits. Do you?
--

Don Kelly snipped-for-privacy@shawcross.ca
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