Sorry Andy, never know who is familiar with what - uS/cm referred to micro-Siemens/cm, the common unit of measurement for electrical conductivity, the reciprical of electrical resistivity! For CaCO3 the conversion to PPM is 2uS/cm = 1 PPM. For Cs it is less then 2 but subject to debate, I prefer 1.6uS/PPM. Basically an ohmmeter with conversion but calibrated to compare to a one sq. cm electrode, to measure the conductivity of one cubic cm of the solution. At $50 each and 2% accuracy the TDS meters are a bargain, but get the PWT or pure water tester as that has a lower range and thus is more accurate!
For Tyndall, any beam of light is fine, a flashlight or laser pointer is OK but I prefer the flash light as the beam is big enough to see contaminates such as crystals or other larger particles, which will sparkle. You aim for a fog type cloud only, as the finer the particle, the better the product, the more stable and thus longer storage life. Not sure about beer making equipment, but specific gravity would not be measurable with the typical spigmomanometer (spelling?), as you need an accuracy of better then 1 PPM or 0.00001%. f...@health2us.com Andy said: Thanks for responding Fred, I'm confused. Is us/cm the same thing as microseconds/centimeters? Wouldn't that be a time measurement? How can you convert that to PPM? Are TDS meters just ohmmeters that do a conversion or is there more to it than that? How about the "Tyndall affect of "light dispersion"?" Can I measure that with the gizmos that winegrowers use out in the field to measure the sugar content of grape juice? I'm trying to figure this all out on a budget. I have some old beer making equipment. Do you think the specific gravity will tell me anything? I was planing on using my test results for quality control but I am looking forward to hearing the results of your extreme tests. Keep us posted. Best wishes, Andy In a message dated 12/09/1999 6:38:35 PM Pacific Standard Time, f...@health2us.com writes: Welcome Andy, There are a lot of expensive scientific instruments that could be used for the testing but for such extreme limits of testing simple stuff can be used! We use two separate TDS digital meters, as made by Hanna Instruments, which measure in us/cm, which can be translated into PPM. TDS or "total dissolved solids" measures via conductivity, what is in the solution, not settlement , so it would detect agglomeration, settlement, crystallization, plate out, etc. We of course had to bring the solutions back to room temeperature, as the temp. effect is around 1%/degree F and we went from 70 to 212F. We check the Tyndall affect of "light dispersion" when a strong beam of light is shown thru the solution and we can see the beam of light, as if shown thru a fog. A visual color check is also made, against part of the same batch, in the same size jar. The former is good for any time of test, even to check a year later, while the latter being visually subjective can only be relied on for very short term tests, where you can keep some of the batch to compare to! Both of these used together provide a good low budget measure of extreme outside effects such as freezing, heating, strong magnetic fields, strong UV light, etc. (Our UV light test was actually from last year, but 3 weeks at 1/2" away, which would be equivilant to years of bright room light levels. The other important element to consider in simple tests, is to use the extremes, as we did, so any effect would tend to be profound! All of these outside forces definately have an effect, but being so trivial should not be of a concern. There is a possibility these forces could exhibit a profound effect on less "pure a silver colloid", since we tested with the best we could make. I will repeat the tests next week with some low quality product that has been produced with silver salts only (starting with high PPM water) and then some with silver crystals (heavy cloud formation and stringing) and finally some good stuff but with the "sludge" mixed into it. That should cover (guess I snipped................................................................. the extremes of all of the home brew, unmetered stuff. Will report back! Others may wish to run a few of these simple extreme tests on their production, before I get back to it. f...@health2us.com
