[MR] Barilla, Glasswort, and Sodium Carbonate

[Towey, Brian]

Friends and neighbors, 

Last year we had a spirited discussion of medieval chemistry, especially of
lye and quick lime.

Noting that sodium carbonate is an important ingredient in glass
manufacture, I wondered where medieval Europe might have gotten it by the
ton.  All the way from the Wadi Natron in Egypt?  That seemed unlikely.  A
chemist on the list assured us that there was no industrial synthesis by
which glassmakers could have made sodium carbonate from, say, other
carbonates such as limestone.

So, where did they get it?

I stumbled across a clue while browsing a list of occupational names.  That
and some dictionary cross-references gave me the following picture:

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Barillaro, Barillari, occupational names: burners of saltwort for making
glass and ceramics

Barilla, n. - Saltwort ash

Glasswort, n 1: bushy plant of Old World salt marshes and sea beaches having
prickly leaves; burned to produce a crude soda ash [syn: saltwort, barilla,
kali, kelpwort, Salsola kali, Salsola soda] 2: fleshy maritime plant having
fleshy stems with rudimentary scalelike leaves and small spikes of minute
flowers; formerly used in making glass [syn: samphire, Salicornia europaea] 

King Lear, Act IV, Scene vi:
  Come on, sir; here's the place: stand still. How fearful 
  And dizzy 'tis, to cast one's eyes so low! 
  The crows and choughs that wing the midway air 
  Show scarce so gross as beetles: half way down 
  Hangs one that gathers samphire, dreadful trade!

Salsola \Sal"so*la\, n. [NL., fr. L. salsus salt, because they contain
alkaline salts.] (Bot.) A genus of plants including the glasswort. 

Soda ash, crude sodium carbonate; -- so called because formerly obtained
from the ashes of sea plants and certain other plants, as saltwort
(Salsola).

And here's the kicker....

alkali [Arab., al-gili=ashes of saltwort] The term alkali originally applied
to salts obtained from plant ashes and is sometimes applied to a carbonate
of sodium or potassium...

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Mystery solved!

Your servant,

Charles Fleming
"Miror Otium Negotium Multum Requirere"