Holy Moly! Stay away from cyanides of any ilk. When acidified they produce hydrogen cyanide which is the old "gas chamber" gas. Hope you are kidding. Reducing agents will convert the metal oxide back into the metal itself, but there is no guarantee that it will stick to the other metal. If it is an uncirculated or proof coin, the hope is that the surface will be cleaned without being stripped.
Well, I researched this on the internet and found that they do use Potassium Cyanide http://www.ncscoin.com/pdfs/conservation_guide.pdf Coins that exhibited normal tarnish were oftentimes dipped into potassium cyanide to strip away their patina and leave them bright. Even the United States Mint’s own curators would periodically spruce up that institution’s collection with a rinsing in cyanide, a risky business given this substance’s highly toxic nature. In fact, the poisonous compound is known to have taken the life of at least one prominent numismatist who, while engrossed in his cleaning endeavors, mistook the deadly chemical for a nearby glass of ginger ale. Fortunately, the use of cyanide to clean coins was abandoned decades ago, and most of the pieces so treated have naturally retoned to some degree. also http://www.numismaster.com/ta/numis/Article.jsp?ArticleId=4580 which this type of cleaning has been used to the detriment of the coins. Next, White discusses a cyanide coin dip. The association of cyanide with murder mysteries involving poison should be enough to turn any budding coin cleaner away from this technique. As White expresses it, "cyanide dips contain poison that can lead to death if ingested. Also, if the dip is acidified it can produce hydrogen cyanide, a lethal gas." Isn't that what they use in the gas chamber for executions? In addition, I'm reminded of Jim Jones and the mass suicide in Guyana by people drinking cyanide-laced grape Kool-Aid. Needless to say, I'm not recommending a cyanide coin dip. Next, we have the ever-popular acid-thiourea dip. This is actually what people refer to when they talk about "dipping" a coin. Truth be told, almost any time you see a brilliant, untoned coin that you would expect to have a measure of toning because of its age, it has almost certainly been dipped. As Scott Travers, writing in The Coin Collector's Survival Manual (5th edition), puts it, "It just isn't possible for 100-year-old silver coins to be as brilliant as when they were minted. Toning is a natural part of a coin's aging process." http://www.coinbooks.org/esylum_v09n32a14.html Cyanide is most effective in cleaning gold and other coins. Another little known use of cyanide is in the electrolyte solution in making coin and medal patterns -- galvanos -- these are oversize patterns made from sculptors models intended to be reduced on a die-engraving pantograph (as a Janvier) to cut a die or hub of appropriate size. Cyanide is ideal component in the electroforming baths for making such copper galvanos. Such technology was developed by the French in the Paris Mint and copied by other mints. I have yet to learn how early it was in use in America (any E-Sylum reader know for certain?). But it was well intrenched by 1920 for de Francisci's Peace dollar and in use at the Philadelphia Mint for the next 40 years. [Copper galvanos were ultimately replaced by an epoxy casting method that reduced the time to make these patterns from days to hours.] http://www.finishing.com/0000-0199/182.shtml http://www.mycoincollecting.com/collecting/cleaning-coins.html
Short answer: you can't, and this is a good thing. I'm still not sure whether you're trolling in this thread, but for the sake of newcomers, I want to make this point very clearly and without a hint of sarcasm: There is a HUGE difference between "techniques that are bad because you'll ruin your coin if you don't know what you're doing" and "techniques that are bad because you can kill yourself, and some first responders, if you don't know what you're doing". Don't use cyanides to clean coins. Don't use them outside of a well-controlled lab or commercial environment, staffed by well-trained professionals. Just. Don't.
To go on a little more about cyanide, I am reminded of Tom Lehrer's Irish Ballad - "Her mother she could never stand, Sing rickety-tickety-tan, Her mother she could never stand, And so a cyanide soup she planned, The mother died with a spoon in her hand, And her face in a hideous grin." Seriously you can get quite ill, if not die just from getting it on your skin or under your fingernails. I used it once to silverplate some NYC subway tokens. I made AgCN and then dissolved it in excess NaCN to use in the plating bath. I was nervous the entire time.
Perhaps I should clarify. I wasn't necessarily trying to talk you out of using cyanide. Just everyone else. Now that we've verified that this has turned into a trolling thread, is it time to lock it?
Not a bad price and it looks like there can be some luster on some of them. If I were doing this, I would take one as a test case and buy some dip (E-Zest or whatever), I would rinse the coin in hot running water from the tap and then dip it for 4-5 seconds in the dip and then rinse it in hot running water. Next either rinse with distilled water or simply place on a soft cotton towel and blot (no rubbing). See how that looks and adjust your technique accordingly. Remember it is easy to over-dip, so take it easy.
Amazon apparently (at least I think it does reading the description) states that you are getting a single coin, their choice of date/MM. http://www.amazon.com/1878-1904-Beautifully-Morgan-Silver-Dollars/dp/B004HA7JDU
cyanide is one dangerous chemical. Don't use that unless you are a skilled chemist in laboratory work. At the very least you need a fume hood otherwise you're going to die. If you are going to work with this chemical you should also have a respirator/gas mask. This is one of those chemicals where you want to take every single precaution to make sure you don't kill yourself and others around you.
If you think you can skip the fume hood and do it outside you're wrong. You could kill your neighbors. any local wildlife and/or house pets. The EPA and law enforcement won't take to kindly to people using these toxic chemicals without proper equipment and experience.