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Rum and Gunpowder - Peter Westergaard

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December 18th, 2012

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10:43 am - Rum and Gunpowder
Rum and Gunpowder. Vincenzo (currently staying with us) and I were talking about "Proof" and how it seemed a strange measure. Why bother to give a name to a number that's just twice the alcohol by volume? Wikipedia says the original value was 7/4, however, not twice. Huh? What, besides being ridiculously complicated would be appealing enough to set something as ludicrous as 7/4 of another measurement as an official imperial measure? Reading further on wikipedia, it set me on the trail of a really curious "origin story" (which, let me be frank, I'm accepting with as much hard truth as superhero origin stories). That was this: Sailors in the 1800s would attempt to light gunpowder that had been soaked in rum. This was ostensibly to verify if their purser had been skimming rum off the supply and diluting it to cover his tracks. Rum diluted below a certain point, says the tale, will wet the powder and prevent its ignition. And that point, says the tale, is 57% abv and change. Or approximately 4/7. So if that exact point (where the gunpowder will ignite) is defined as "100 degrees proof", then you convert %abv to proof by multiplying by 7/4. Wow. So the next question is: Does that in fact make sense? Surely it would depend on the quality of gunpowder and possibly on atmospheric humidity. I suppose the quality of the gunpowder in the 19th c English navy could be relied upon to a certain degree. But to within a few percent tolerances? I really don't know. And not having access to period black powder, I went reading online... and found that someone had already DONE this test! http://www.theatlantic.com/magazine/archive/2010/11/gunpowder-on-the-rocks/308251/ How cool! And even though he hadn't (evidently) read the 57% (or 4/7) comment on wikipedia, his experiment seems to imply that 57% was about the cutoff. That was an interesting note. Though as the author also notes, other alcohols evidently scoffed at the proof level anyhow, so chemistry may have a lot to do with it. In any case, it was certainly interesting, and reminded me how ludicrously precise imperial things can be. Even so far as to measure alcohols (again, from wikipedia so ymmv) with fractional specific gravity (12/13 in this case for 100 degrees proof, though I haven't done the math there to verify it corresponds to the 4/7abv).

Current Mood: curiouscurious

(4 comments | Leave a comment)


[User Picture]
Date:December 18th, 2012 03:51 pm (UTC)
You are such a geek....but you're adorable with it....
[User Picture]
Date:December 18th, 2012 05:33 pm (UTC)

I'm impressed by how scientific Imperial measurements could be, but that in many cases the science was flawed. Fahrenheit was supposed to be an absolute scale, with zero being as cold as the creator could duplicate experimentally. Obviously not a North American scientist...
[User Picture]
Date:December 19th, 2012 04:02 pm (UTC)
Fahreheit was invented by a German, not a Englishman :)

And actually, it is pretty accurate for what it *is* based on: the freezing point of brine (salt water) and the average human body temperature ("blood warm"). The original scale was multiplied by 4 (to eliminate fractions for certain common usages) and then recalibrated to put freezing and blood warm 64 degrees apart in order facilitate the marking of mercury thermometers (also invented by Daniel Fahrenheit). The setting of "zero" at the coldest day that winter is a myth.
[User Picture]
Date:December 19th, 2012 04:54 pm (UTC)
I know it was invented by a German "Fahrenheit" is a good clue :-) But it's lived on as an imperial measure, and I agree with you completely; you made my point much stronger on it's scientific soundness.

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