If it were mine I would sprinkle on the roses, they will love it. The stuff has got to be at least 30 years old, there is no current data for it. Open the can, if it don't have an acetone smell it is suspect. If it has a sour smell take it on out and put it right on the flower bed, sprinkle it out well don't let it be in any kind of pile that could burn.
Yes that is my secret to those nice homemade roses that are almost always in our house in the late spring and early summer. I tell that to my wife's friends that can't grow roses, but I don't think they belive me. Silly yuppie ladies, both Nitro and blackpowder is good fer roses and it is a safe way to dispose of it with out havein' ta deal with the local Federale's their little red car and a box they slapped EXPLOSIVES all over before takin' it away. So much for tryin' to do the right thing!