On 27 Mar 98 at 10:34, Fred Walter wrote: > >From: "M. G. Devour" <[email protected]> > >To do the latter, you need a standard solution
> Can you give me a few more details? ... I'd rather not spend $24 > CDN ($15 US) to buy calibrating solution from them if there is some > easy obvious way of making it. I haven't done the figuring yet, but I assume you could take a gallon of distilled water and add a level measuring spoon full of granulated salt to get a pretty reproduceable and reasonable value of concentration. I need to find out how much salt (by weight) is in a half-teaspoon measure, for instance. If it's just a few tens of milligrams and we know how many liters are in a gallon, you ought to be able to calculate the milligrams of salt per liter. That is exactly what the ppm is. If we have to, we could use a two step dilution, making a saline solution in a gallon and diluting it further to get it into a range that is close to where we want to measure. The key thing is to make the steps simple and easy to do accurately. > >Now we know, *FOR DONNA'S CS ONLY,* that a meter reading of 11.5 > >(averaging the 11 and 12 ppm readings before and after) is equivalent > >to about 17ppm of silver as tested by the lab. Her calibration factor > >would be 17/11.5 or about 1.5. > > I've read that the relationship is non-linear, so it is likely only > 1.5 for readings of 11.5 ppm on your meter. But it is better than > nothing. It depends. Rose and I have tested a couple of different materials other than sodium chloride, and found that the meter is accurate at the low end and starts to roll off (read low) when you get much above 100ppm. Since most of us are trying to make CS that is at least less than 50 ppm, it might be quite workable. Somebody still has to make a pretty dense batch of silver, upwards of 30 or 40 ppm as measured by the lab, and then test it and several dilutions down to say 5 ppm and see if it is linear in that range. If so, we'll be okay. Those are my thoughts right now. I still have to send in my next samples to the lab, as well as figure out an easy to make salt standard. If you want to try your hand at it, all you need is *some* kind of very accurate scale, so we can figure out the weight of any standard size measuring spoon of salt. From there it's straight arithmetic. Has anybody already done this? Mike D. [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]>
