How To Clean An 1878 Silver Dollar?

I would just leave it alone, anything that you could use to remove the "tarnish" would ruin the coin and everyone likes original. If you did use something to clean it you would lose almost all collectivity of the coin. As a side note 1878 has allot of VAM's (if I am not mistaken more than any other date) not to mention you have a 7TF version, and you have a 7/8TF version, and a 8TF version, and even a reverse of 79 Version which could add to its value so if you could take some clear pictures of the Obverse and Reverse we may be able to attribute it with the correct VAM and tell you if it is a highly sought after VAM or not

Go for the acetone treatment. I am slowly discovering the strength of the liquid and it can do some amazing things to yucky gluey gunk.

Also, I'd like to echo the safety protocols from SuperDave. Be careful with the stuff. A splash in the eye... a fire in your face... ouch. Be careful of filling up a closed garage with vapors and having the pilot light of your water heater or something like that ignite everything to smithereens.

-- Boris

Peroxide won't help a whole heck of a lot.

OK. You'll need pure acetone - it's the active ingredient of most nail polish removers and commonly mixed with other substances in that application. It can be purchased "pure" at Home Depot or the like. Acetone is an organic solvent, and will remove organic contamination (including most adhesives) from coins.

Here's how I do it. I use a clear jigger glass, round on the inside and large enough so the coin immerses completely. It allows me to tilt the coin with a toothpick to remove it when done. I use a small pane of glass as a cover - an entire jigger of acetone will evaporate overnight if not covered. You want the container clear, so you can see the progress - when the acetone becomes to any degree cloudy you want to change it so as to carry off contaminants.

Initially I allow an overnight soak, except in the case of very dirty coins where the acetone will carry off the first layer and become cloudy in an hour. After 12-24 hours, I change the solution and allow another 12 hours' soak, whether the coin "looks" done or not, to ensure nothing remaining on the coin. Acetone is water soluble, and given its' rapid evaporation is recommended by many (myself included) as a final rinse for silver. An acetone rinse leaves nothing behind, as long as there was nothing organic still adhering to the coin.

Acetone will not affect "toning." This is silver sulfide, an oxidation byproduct and not organic.

Acetone will not react with silver. It is not possible to determine if a silver coin has been soaked in acetone. You can leave a silver coin in clean acetone indefinitely without harm.

I repeat my warning: acetone is voraciously combustible. Use it only in a very well-ventilated area, far away from any possible source of a spark. Treat it with respect, or it will make you wish you had done so. Do not handle it without skin protection - some (although not myself) are sensitive to contact, and even if you aren't you don't want it getting into a cut. You've never experienced pain like it, and I speak from experience here.

That's a "tone line", you can see the the way it blends into the toning around the rim

That coin has already been cleaned harshly, so you don't have to worry about ruining it's value.

It's not a bad looking coin. Whatever faults someone did to the coin was out of your control. Just leave it.

No, I wasn't saying that YOU cleaned it harshly. Someone sometime had taken a brush to it, though, because there are scratch lines that are visible from the picture.