On the subject of using salt for meter calibration standards, Bill Schramm wrote:
> A half a teaspoon [of salt] would be between 3 and 4 THOUSAND > milligrams if it were of water. 28000/12 is about 2300 milligrams, close enough! > There is not necessarily a relation between volume and weight for a > solid substance such as salt: the coarsness of its grind will make > a difference. This is a *very* important thing to keep in mind when doing any kind of conversions of weights and measures. I've seen a *lot* of mistakes made converting between volume and weight measures. > So get a gram scale and weigh it. Not everyone has access to a scale or balance that can measure materials with enough accuracy. That's why I'd like to see if there's a way to make a decent standard using kitchen tools! Wherever I've been in the US and Canada, common table salt has always been indistinguishable from one place to the next. I'm hoping that at least for *many* people, a teaspoon of table salt will have a pretty reproduceable *weight*. I couldn't speak for our members in Britain, South Africa or Australia, however! Anyway, it seems that a two-step dilution will get us down to a few tens of ppm and be easy enough to do. I'll have Rose measure out a few teaspoons full and weigh them to see what they weigh and how reproduceable a measuring spoon is. Then we can cook up the rest of the dilution recipe and let others try it. Another alternative is to find a source for an inexpensive but accurate balance that can measure a few grams at a time to fractional milligram accuracy. I think I've seen a couple of examples that could do in a pinch. Here's another cottage industry for somebody to start up. Get a decent balance and start making cheap salt solutions for the rest of the list! Or even just mail out the measured packets of salt! (Just be careful who sees you doing this, as dividing up small portions of white granular powders and putting them in plastic bags could look a *mite* suspicious in those jurisdictions where certain medicinal or recreational substances are regulated or prohibited. <grin> ) Of course, the suggestion of asking your friendly pharmacist to weigh some out for you is also quite workable. I'm sure we can work it out. Be well, Mike [Mike Devour, Citizen, Patriot, Libertarian] [[email protected] ] [Speaking only for myself... ] -- The silver-list is a moderated forum for discussion of colloidal silver. To join or quit silver-list or silver-digest send an e-mail message to: [email protected] -or- [email protected] with the word subscribe or unsubscribe in the subject: line. To post, address your message to: [email protected] List maintainer: Mike Devour <[email protected]>
