These are great comments, Frank. This is why I asked for input! Frank wrote:
> Great and creative ways to seperate the silver from water, but why > not just weigh the solution? 1 litre of pure water weighs 1 Kg so > anything over 1000gms is silver. I'm trying to figure this out as I type, so please bear with me. To measure, say, a 20 milligrams change in 1000 grams of water, you're trying to detect a 2x10^(-2) / 1*10^3 = 2x10^(-5) change. Decent analytical balances seem to be good for at least that. Let's see, here's a Mettler AB104 in the Fisher scientific catalog, costs about $2000 US. It'll read to 100 grams with .1 milligram precision. That's good for one part in a million, so theoretically I could measure the mass of 100ml of CS and, with tenth-milligram sensitivity, and know the concentration to the nearest 1 ppm. Okay, what problems can I think up? How would I measure the *volume* of the sample accurately enough? That would be tough. Even being off by a drop would shoot the accuracy all to hell. (There's about 20 drops per ml, 2000 drops per 100ml, so 1 drop is 1 part in 2000, or 500 ppm. Even weighing the whole liter, a drop represents about 50 ppm!) If I try to detect the weight *gain* of a pre-measured quantity of water, then I'd again have to avoid the loss of even a drop. With the usual condensation on the inside of the lid, and with product clinging to the electrodes that would be tough. Damn! Wait a minute, weigh the electrode assembly right after the run is complete, so you capture the mass of the water lost that way. Then dry the whole think in the oven and weigh it again. You can now restore the "lost" water to the weight of water you started with. What scares me is trying to weigh the water and the jar it's in. That starts to push you beyond the max. capacity of most of the balances that are sensitive enough. It's a tantalizing idea, but can we make it work? > Better yet! You could weigh the electrodes before and after(dried). > Anybody got any ideas on how to build a scale sensitive enough to > register the small amounts? Is a beam type scale practical? A triple beam balance seems to be good for .1 gram to .01 gram sensitivity, so that would be rough. The better balances, as above, would do it though. Now this sounds doable. Just be sure the wires are really clean and dry before weighing and you'd be able to detect fractional milligram changes in mass. ( Even fingerprints are significant when you're working with these kinds of quantities.) You would have an upper limit on the total silver consumed in the process. But if we aren't using salt, but only distilled water, we always get fluff at the negative electrode as well as oxide at the positive electrode. Wipe these away and you'd really not know what's still in the water. Okay, bear with me again as I try a mind-experiment... Weigh a couple of pieces of filter paper to .1 milligram accuracy. Weigh the clean and dry electrodes with the same care. Handle the electrodes with gloves to avoid body oil contamination, etcetera. Make your run, without disturbing the oxide or "fluff" that accumulates on the wires. Afterwards, remove the electrodes one at a time, trying not to leave any big pieces of fluff in the vessel. Place the electrodes, still wet and full of fluff or oxide, on the pieces of pre-weighed paper. Bake in oven to drive off the water. Weigh the combined paper/electrode/dried fluff. (Don't sneeze!) Subtract the paper and you'll get the actual mass of silver that *didn't* go into the water! (You'll even have separate measurements for the two electrodes.) Okay, you might need to pre-bake the paper as well, to drive off any volitiles or moisture, then keep it in a clean covered dish. If you filter the CS, you'll also be able to capture the mass of anything big that got left in the water. Just do the same bit with weighing the paper. How about sensitivity? Some recipes make as little as 8 ounces of CS at a time, or about 250 ml or 1/4 of a liter. So for 10ppm, 1/4 of a liter would be about 2.5 milligrams you'd be trying to capture. My entire electrode assembly (wires and holder) weigh only about an ounce (about 30 grams), so that's well within the range of the balance. Doable, but I bet the error bars on this will be about 10% when everything is accounted for! Damn, Frank! I think that might be workable. It's a little more effort than I might like, but at least it's possible. <grin> This idea may take care of the CS we're making ourselves, where we can get to the electrodes. It doesn't help in the case of CS that's already made. It requires posession or access to a pretty expensive balance. A number of us may have such access, since many labs at universities, hospitals and the like will have them. > Just a couple thoughts. Hey Frank, that why we pay you the big bucks! <grin> Good job... I'd still like to be able to measure the total silver in an existing sample, so let's keep this discussion going, please. I think you can see where I'm trying to get to... Be well, 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]>
