[Avodah] Are there any chemists on Avodah?

[Micha Berger]

On Fri, Jan 07, 2011 at 01:50:55PM -0500, Hankman wrote:
: Mamcheh appears to mean "to disolve", according to Dr Jastrow. So I
: don't a mixture, while accurate, is necessary the right mental image. I
: think the lime is being used as an alkaline (wikipedia says it's caustic)
: to reduce the lead. Bitumen and pitch, both tarry, are nore likely
: to react with lead, but if we have a chemist rather than someone doing
: web searches, it would help.
: 
: But back to the point, the lead was machah, and therefore not in a
: shiny metal form when used for mortar. I'm figuring the verb holds
: the answer, regardless of the chemical details.
: 
: CM asks:
: 
: Please explain two of the words you use. Tarry means ?, and "machah," is this a typo for mamcheh meaning to dissolve or some other word whose meaning I do not know? What is the right mental image? How do you get this from "dissolve"?

I was referring to the shoresh of mamcheh, /MCA/. Jastrow pg 736 lists
mamcheh in a discussion of /MHH/ and /MCA/, and says both roots mean to
dissolve, disolute, or to make clothes threadbare and ragged.

See also his entry for mecha and mechi, pg 759. "Blot out" comes up;
and think of the word "macha'ah".

There is a copy at <http://www.tyndalearchive.com/tabs/jastrow>.

: I strongly suspect (by analogy to other archeo concrete) that the lime
: is a primary component of the final mortar, and not just primarily used
: as an alkaline caustic to reduce (what reaction exactly do you mean?) the
: lead (although there of course could be some secondary chemical reactions
: going on?)...

I am wondering if mamcheh means the lead was dissolved, rather than
a visible part of the result. It does look that way. OTOH, the word
"machi" is used when making a porridge out of parched grain, which isn't
a full disollution.

I don't know about other ancient concrete, I'm just playing with the word
definition and an on-line Jastrow.

:-)BBii!
-Micha

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