[Sca-cooks] Baker's borax

[Terry Decker]

According to Wei, Zheng, Liu, Cai and Nie, "Discovery of Borax-bearing 
Mirabilite Beds in Dong Co, Northern Tibet, and Its Palaeoclimatic 
Signifcance," Acta Geologica Sinica, the Tibetan borax derives from five 
mirabilite beds.  Mirabilite is a form of hydrous sodium sulfate commonly 
associated with a number of other minerals including trona (natron).  Not 
much I would want use as leavening.  While some of these compunds will 
effervesce, the sulfates tastge pretty lousy and can poison one.

Chambers's Encyclopedia notes that carbonate of soda is found in the natron 
lakes of Hungary and Armenia in conjunction with sulphate of soda and 
chlorite of sodium.

If you check on the geology of Lake Van (in Armenian control from Antiquity 
but now in Turkey), you will find an alkali (sodium salt) lake that produces 
sodium carbonate, sodium borate, sodium sulfate, and sodium chloride.  A 
source of "Armenian borax" which contains a form of natural chemical leaven.

I would suggest that both borax and natron are being used more generally in 
Medieval documents than they are modernly having been assigned greater 
scientific precision in the Modern Age.

Bear

> Some more on the borax issue ... .
>
> The reference to natron isn't in the text itself, it's in the translator's 
> glossary, based on period sources but not necessarily al-Warraq, who I 
> think only refers to bakers' borax. She says that there are two kinds of 
> borax, natron and Armenian borax also known as bakers borax, and that "due 
> to natron's cleansing qualities, people use it to wash their bodies and 
> clothes. Sprinkling it on the hair helps soften it." There are some other 
> comments about borax that don't distinguish the two kinds, as something 
> that is not recommended to be taken internally save for medical purposes.
>
> She thinks it is sodium borate, but that doesn't explain either why there 
> are two kinds or why it would be used as a leavening, although it is 
> consistent with using it for cleaning things. Also, according to one 
> source online, the lethal dose of borax for adults is 15-20 grams. 
> Al-Warraq's recipe for Barazidhaj uses 2 ounces of bakers' borax for 7 1/2 
> lbs of flour, which means that someone who ate a third of a recipe over a 
> period of a few days, which sounds plausible enough, would be getting a 
> lethal dose. On the other hand, Wikipedia describes it as sometimes used 
> as a food additive--it doesn't say in what quantities--and makes it sound 
> as though it is lethal only in high doses, but dangerous enough to be 
> banned in many countries for food. It also says "Its use as a cooking 
> ingredient is to add a firm rubbery texture to the food, or as a 
> preservative. In oriental cooking it is mostly used for its texturing 
> properties." That doesn't sound like either of the uses mentioned for 
> bakers' borax.
>
> Wikipedia says that borax was being first discovered in dry lake beds in 
> Tibet and imported via the silk road to Arabia--which would suggest 
> something much too expensive to be commonly used for washing with.
>
> The modern meaning of "natron" is a mixture of sodium carbonates, 
> including some baking soda, which fits the facts she gives much better 
> than sodium borate does. According to Wikipedia, it occurs naturally in 
> dry lake beds in Egypt and has been used for thousands of years as a 
> cleaning product, which against fits much better.  I'm guessing that the 
> bakers' borax is something similar to natron with a different mix, 
> possibly a larger percentage of baking soda.
>
> -- 
> David Friedman
> www.daviddfriedman.com
> http://daviddfriedman.blogspot.com/
>
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