To All, Many people have commented on the drop in conductance after the brew is finished. It can be quite significant, and can reach 40% to 60% of the original strength in the first 48 hours after the cs is put in storage.
This can greatly reduce the effectiveness of the cs, especially when the silver ion concentration is marginal to begin with. High Ion Concentration Is Needed ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When the cs is weak, and you are fighting a particularly virulent Herpes Simplex or Herpes Zoster virus, you can drink as much cs as you want and it will have little or no effect. But if you can raise the ion concentration to a true 20uS or more, the infections are quickly subdued. For example, please see my post to Sol on 19 Oct 2004. Note that Sol also found that a stronger cs worked better for her as well. (The mail archive scrambles email addresses, so please replace the (at) with "@") http://www.mail-archive.com/silver-list(at)eskimo.com/msg76134.html Silver Sulfide Tarnish ~~~~~~~~~~~~~~~~~~~~~~ I have finally tracked down the cause of the drop in conductance, and figured out how to to solve it. The drop in conductance is caused by silver sulfide - plain ordinary silver tarnish. Interestingly enough, it is also the reason your cs turns purple when you take sips from the main storage container, instead of transferring it to a smaller container. It is caused by the sulfur ions in the solution, and not by the silver ions as everyone assumes. Sulfur is everywhere in the environment. It is largely generated in automobile combustion and fossil fuel generating plants. It also comes from the water traps in the kitchen and bathroom sinks as sewer gas, or hydrogen sulfide, H2S. [1] Keep Your Plumbing Clean ~~~~~~~~~~~~~~~~~~~~~~~~ You may notice an unpleasant odor sometimes when you go near the kitchen sink. That is an indication it may be time to clean out the gunk and old food debris that accumulates on the walls of the downspout. I use an old coathanger with a small hook bent at one end, and a small flashlight to show where the gunk is. It takes a bit of work to find all the gunk and knock it into the trap. Flush with water from time to time so you don't end up with one gigantic ball that can plug the pipe. When you are done, your sink will thank you. It will drain much faster than before, and will smell fresh and clean, at least for a few days. Doing it yourself is a lot better than having to pay a plumber when the drain becomes completely plugged. If you have a garbage disposal or a dishwasher, the situation is a bit more complicated. It may require disassembling the drain pipes to remove the gunk. This is a messy job, but well within the capability of a handy homeowner. Here are some links that can help: http://www.freeplumbingtips.net/public_html/KitchensinkCDTS_1.htm "http://plumbing.about.com/od/drains/ss/Clearing-A-Clogged-Kitchen-Sink-Through-The-Trap.htm"; Keeping the plumbing clean helps to minimize the amount of sulfur generated from bacterial action, and helps to minimize the resulting tarnish that forms on the silver electrodes of your cs generator. Sulfur Chemistry ~~~~~~~~~~~~~~~~ Sulfur loves to combine with silver. Anyone who has silver utensils knows how hard it is to keep them free of tarnish, and clean and shiny. The chemistry is deceptively simple: H2S + 2Ag --> Ag2S + H2 [2] However, silver tarnish is one of the most insoluble of all silver compounds. The solubility is only 8.5e-12 mg/L in water, which makes it extremely difficult to remove. [3] The film of tarnish does not have to be very thick to have a severe impact on the brewing process. The ion concentrations we work with are so low that the tarnish film can be completely invisible and still ruin your brew. Cleaning Tarnished Coins ~~~~~~~~~~~~~~~~~~~~~~~~~ Coin collectors use a simple electrochemical process to remove tarnish from silver coins using aluminum, baking soda and hot water. Here is an example of how it works: http://www.youtube.com/watch?v=ij4QynD7Ao8 This relies on the galvanic action of aluminum and silver to generate a small voltage between the silver and aluminum which drives the reaction. But we don't want to subject our silver electrodes to a solution of baking soda. This could contaminate the electrodes and be very difficult to remove. Instead, we can use our knowledge of silver chemistry and our cs generator to supply the dc current needed to convert the silver sulfide back to silver. To perform this magic, cut a strip of aluminum foil an inch or so wide and place it in the generator so it is halfway between the electrodes. Fill the container with dw, and if you have a Hanna or COM-100, measure the conductance of the water. Now connect the positive terminal of your supply to the aluminum foil, and the negative terminal to both electrodes. Turn on the current and wait. Here is an example of a typical conductance plot using a constant current of 500uA. The red curve is the cell voltage using the scale on the left, and the blue curve is the cell conductance using the scale on the right. Note the cell conductance quickly increases, followed by a characteristic double hump in both curves. This indicates there are two separate reactions occurring that are separated in time. The reason for this double hump is still under investigation. http://pstca.com/misc/3f2b6ba5.gif When the reaction is complete, the conductance stabilizes at a low value. This indicates there are very few ions left in the solution to conduct current. If you stop the process at this point and remove the electrodes, you may notice a slight silver sheen on the surface of the dw. This is caused by silver atoms released by the sulfur enclosing hydrogen gas formed at the cathode. The bubbles rise to the surface and he hydrogen gas escapes, leaving a thin monoatomic layer of silver floating on the surface. If you measure the conductance of the dw with your Hanna or COM-100, you will find it is virtually identical to the original reading you took before applying the current. So we have created a reaction that filled the dw with two sets of ions, then the reaction self-terminated and the conductance of the dw dropped back to the value of the original dw. And the electrodes are now both a dull gray color. The conclusion is we have removed compounds from the silver electrodes and deposited them on the aluminum foil. The compounds expected are silver sulfide, and any other anions or deposits from the distilled water. Chemical Equations ~~~~~~~~~~~~~~~~~~ I originally intended to supply the chemical equations that show the process at this point, but I have uncovered what may be a significant error in the classical explanation of what is happening. I will study this further to see if I can determine the reason for the discrepancy. However, this does not stop you from performing this operation on your own electrodes and enjoying the benefits of increased ion concentration in your brew. Results of Desulfurizing ~~~~~~~~~~~~~~~~~~~~~~~~ My brews used to lose a great deal of conductance after the cs was placed in storage. I usually saw between 40% to 60% drop, and the Salt Test confirmed the loss of silver ions. It was very weak. Now, the brew loses less than 12% of the initial conductance, and I get consistent readings above 30uS. The Salt Test and Faraday calculation both confirm this concentration is accurate. Storing Your CS Generator ~~~~~~~~~~~~~~~~~~~~~~~~~ Now that you have cleaned the electrodes and hopefully can start to see an improvement in your readings, it would be a shame to let the tarnish form again and return things to the way they were before. One thing that can help is to keep your sink plumbing clean, as described above. Another way to minimize tarnish buildup is to store your generator in clear polyethylene bags like the ones used in the vegetable section of grocery stores. I prefer to use two bags to help minimize the seepage of hydrogen sulfide through the bags. The tarnish and other deposits from the dw will eventually build up again, so this process needs to be repeated whenever you notice any degredation in your brew. Best Regards, Mike Monett SilverCell Links ~~~~~ [1] http://telstar.ote.cmu.edu/environ/m3/s4/cycleSulfur.shtml [2] "http://www.tippcityschools.com/16912052313413413/lib/16912052313413413/HW%20Answers/NDG_007AD.pdf"; [3] http://en.wikipedia.org/wiki/Silver_sulfide -- The Silver List is a moderated forum for discussing Colloidal Silver. Rules and Instructions: http://www.silverlist.org Unsubscribe: <mailto:[email protected]?subject=unsubscribe> Archives: http://www.mail-archive.com/[email protected]/maillist.html Off-Topic discussions: <mailto:[email protected]> List Owner: Mike Devour <mailto:[email protected]>
