Keep a record of your dung jar on a sheet of paper. I placed it in a pint jar on some paper towel with just enough water to wet the towel. Manure is green-black. Manure is turning blacker. I would be delighted to receive an e-mail from you describing how you did this experiment and what happened.
All good scientists report their results.
I will publish the best reports on my web site. Click here to read the results of other people's dung jars. That page also links to reports on other projects. A slight variation of dung jars is to place wood such as a piece of a tree limb in a jar. Select a weather beaten tree limb with or without bark and cut to 6 inches long or any convenient length, stand it on end in a quart or larger jar.