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<DIV><FONT face=Calibri><FONT face="Times New Roman">On Wed, Jan 05, 2011 at
02:37:52PM -0500, Hankman wrote:<BR>: In the daf, 54a, the gemara brings a Tani
Levi that describes the<BR>: construction of the Misbeach. It was concrete-like
in nature. It used<BR>: forms much as we would today, aggregate of perfectly
smooth stones<BR>: (not to be felt when passing a fingernail over them) and some
sort of<BR>: matrix or "mortar" composed of some sort of mixture of sid, kunya
and<BR>: zefes, commonly translated as plaster or lime, lead, and pitch or<BR>:
bitumen. My question is about this "mortar" they used...<BR></FONT></FONT></DIV>
<DIV><FONT face=Calibri><FONT face="Times New Roman"><FONT face=Calibri>RMB
wrote:</FONT></FONT></FONT></DIV>
<DIV><FONT face=Calibri><FONT face="Times New Roman"><FONT
face=Calibri></FONT><BR>Mamcheh appears to mean "to disolve", according to Dr
Jastrow. So I<BR>don't a mixture, while accurate, is necessary the right mental
image. I<BR>think the lime is being used as an alkaline (wikipedia says it's
caustic)<BR>to reduce the lead. Bitumen and pitch, both tarry, are nore
likely<BR>to react with lead, but if we have a chemist rather than someone
doing<BR>web searches, it would help.<BR><BR>But back to the point, the lead was
machah, and therefore not in a<BR>shiny metal form when used for mortar. I'm
figuring the verb holds<BR>the answer, regardless of the chemical
details.</FONT><BR><BR>CM asks:</FONT></DIV>
<DIV><FONT face=Calibri></FONT> </DIV>
<DIV><FONT face=Calibri>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"?</FONT></DIV>
<DIV><FONT face=Calibri></FONT> </DIV>
<DIV><FONT face=Calibri>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?). Of course this is but a gut feeling
without any proof. I doubt highly that the pitch was a primary component because
then I imagine the mortar would be more in the nature of some sort of asphalt
and be a problem at elevated temperatures of the fires on the surface of the
mizbeach. I also doubt the primary component was the lead for the reasons I
posted as my original questions in my first post. So if as you assume the lead
is "reduced" (whatever that means) chemically, what is its function in the final
mortar? Ditto, I was also looking for the function of the pitch (or
bitumen).</FONT></DIV>
<DIV><FONT face=Calibri></FONT> </DIV>
<DIV><FONT face=Calibri>So like you said, we wait for either a chemist or a
material scientist to comment for a clearer explanation (if any be
known).</FONT></DIV>
<DIV><FONT face=Calibri></FONT> </DIV>
<DIV><FONT face=Calibri>Kol Tuv</FONT></DIV>
<DIV><FONT face=Calibri></FONT> </DIV>
<DIV><FONT face=Calibri>Chaim Manaster</FONT></DIV>
<DIV><FONT face=Calibri> </DIV></FONT></BODY></HTML>