Today, a brilliant chemical engineer provides grist
for the alchemists' mills. The University of
Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
The great chemist Maria the
Jewess has been pretty well lost in the blur of
ancient history. Most of what we know about her
comes from the Egyptian alchemist Zosimos, who
wrote in the late days of the Roman empire, 500
years after Maria lived. Among other things,
Zosimos talks about her invention of the kerotakis.
Maria invented many types of stills and reflux
condensers. The kerotakis device was one in which
she could boil mercury or sulfur and use its
condensing vapor to heat copper or lead in a pan
above. It was a kind of high-temperature double
Remember how a double boiler works: It has an upper
pan where you cook food, nested in a lower pan of
boiling water. The food stays at the same
temperature as the steam condensing under it -- 100
degrees C. And so the one reference to Maria in the
modern world is the French word for a double
boiler. They call it a bain-marie --
Maria gave us far more than just the double boiler
-- significant as that is. She founded an important
school of chemistry in the late 3rd century BC. She
worked a little after Euclid. She could well have
known Archimedes in Alexandria.
Scholars speculate on her origins. She's called The
Jewess because Zosimos called her a Sister of
Moses. That could well've been no more than a
convoluted way of saying she was wise. She could've
been a Greek working in Egypt, or even a Syrian.
She studied sulfur compounds. It was Maria who
created the process for making silver sulfide --
what artists call niello. That's a matte black
compound, often used for metalwork inlays.
Maria wasn't really an alchemist. She was less
interested in the philosophy of transmutation than
she was in practical chemical processes. The
alchemists of a later age used some pretty fanciful
and metaphorical language to describe her
processes. But that was their rhetoric, not hers.
Maria was closer in her thinking to Egyptian
process engineers -- like the Egyptian women who
developed the process chemistry for brewing beer.
Maria was closer kin to today's chemical engineers
than she was to the philosphers of a later age --
who made such heavy use of her stills and her
And the French word bain-marie is the
only place we still hear her name today -- that and
the French slang term, femme au
bain-marie, which means an empty-headed
pretty woman, a woman with a double boiler for a
Now there is a sorry reminder of how much we've
forgotten -- about who Maria the Jewess really was,
and all she accomplished.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
Multhauf, R.P., the Origins of
Chemistry, New York: Franklin Watts, Inc.,
Taylor, F.S., The Alchemists, New
York: Arno Press, 1974.
Federmann, R., The Royal Art of
Alchemy, (tr. by Richard H. Weber),
Philadelphia: Chilton Book Co., 1964.
I am grateful to Kathryn Krause, UH Library, for
locating a great deal of good source material on
Maria the Jewess.
The Engines of Our Ingenuity is
Copyright © 1988-1997 by John H.
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