Lessons on Alloys, Amalgams, and Pleonasms (3)

Keith P. Walsh is spreading drivel again (August 25, 2007). As usual he is confused, and he may be confusing readers of both the sci.med.dentistry and sci.materials newsgroups. He needs to take some lessons rather than try to give them.

In the last post of this series we saw that the Metals Handbook, Desk Edition (2nd, 1998) defines an amalgam as: "a dental alloy produced by combining mercury with alloy particles of silver, tin, copper, and sometimes zinc".

The time-tested Metals Handbook definition is a sensible description for what an amalgam is. Based on this definition (of course):

Point 4: The phrase "mercury amalgam" is a pleonasm.

Alloys containing gallium or indium (but no mercury) are more sensibly described as alloys, not as amalgams.

Reading Keith's posts is like watching the repeating scenes in the movie "Groundhog Day". It's not like life, or a box of chocolates, because you already know exactly what you're going to get.

Pittsburgh Pete Aka "Dancing With Trolls"

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I'm sorry Pittsburgh Pete but I'm afraid I still disagree with you on this.

I think that it still makes much more sense that any material that is formed by mixing together bits of solid metal together with a liquid metal at a temperature which remains below the melting points of the solid metals should be called an "amalgam", regardless of whether the liquid metal amalgamating agent used is mercury, gallium, indium, or any other.

In fact I believe that it was probably the general formation of this type of material that the word amalgam was originally intended to describe, and not exclusively those examples which are formed using mercury.

And I think I've found some more people who appear to agree with me. They're Daniel Flanagan Baldwin and Rajan D Deshmukh, of New Jersey in the US, who have developed a "Semiconductor device having a layer of gallium amalgam on bump leads".

You can read all about it at:

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They describe the "gallium amalgams" they have used at great length, e.g.:

" .. the gallium amalgam comprises at least 65% by weight gallium,

21.4% copper and 3.6% nickel."

And there doesn't appear to be any mercury in them at all.

I think that this should now settle it once and for all. The term "mercury amalgam" is NOT a pleonasm, because on its own the word "amalgam" is not sufficient to distinguish between mercury amalgams and gallium amalgams.

Keith P Walsh