The subject line says "SU carb", but this is really about Coke and Tang.
John Wr. tells us about "spilled Coca-Cola, [and] a lurking jar of
Tang Breakfast Drink, which will undergo some kind of remarkable chemical
reaction with the Coke and be converted instantly into indestructium"
One of the ingredients in Tang was (is?) a viscosity enhancer called sodium
carboxymethylcellulose (known as CMC), one of the few water-soluble forms
of cellulose. It was typically made from cotton or wood pulp. Unfortunately,
its solubility isn't so great in lower pH solutions. Several prior lives ago,
I worked in a testing lab at a chemical plant that made this stuff. The
various softdrink companies were experimenting with CMC at that time for
the diet versions of their standard products. The reason was that they had
recently switched to paper cartons instead of plastic or glass for holding
the syrup in drink machines, and the viscosity reduction caused by having no
sugar was increasing the frequency of leaky cartons. I got to see firsthand
what happens when you try to dissolve CMC in in softdrinks. Depending on the
situation, it may or may not dissolve, and if dissolved, it may precipitate
out. My recollection was that Coke had a pH of about 3.2, but the worst was
Fresca, which I remember as about 2.7. CMC wasn't happy with this stuff.
When I *could* get it to dissolve, it would slowly come right back out of
solution, so by morning that sample would be a cloudy, pulpy gelatinous mass
(The gelatinous cube hits you!). I don't really know how Tang used it, seeing
as how Tang is pretty acidic too. Once precipitated, it was basically a mess.
So your Tang/Coke "experiment" wasn't out of line with what should have
happened, especially if the floor's own contributions (like battery acid,
maybe?) helped lower the pH enough. You may have had the only TR-3 in
existence with such a high-tech, food-grade sealant!
Jim Muller
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