I have carried them with me for a while now and have used them, and I found the same result as Ruen did.
I've been told, but haven't confirmed through use yet, that if you already have the specific buff it chooses to give you, it renews the time on it. I don't have an Alchemist Stone yet (not enough rep), so I can't confirm that it works with these, though I don't see why it wouldn't.
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"the people can always be brought to the bidding of the leaders. That is easy. All you have to do is tell them they are being attacked and denounce the pacifists for lack of patriotism and exposing the country to danger. It works the same way in any country."
Hermann Goering, April 1946.