Hardware store acetone is not going to be anhydrous and probably nowhere near dry enough to do this without wasting some product. you can dry your acetone with stuff like anhydrous epsom salt and other dessicates, although they might deposit in the material you are trying to purify. if your amphetamine still looks or feels wet when there is no more acetone smell, or if you see liquid left in your glass jar where you dumped the acetone but there's no smell coming off it then your acetone has water in it. save that jar for when you run out of speed and don't mind smoking your acetone wash for whatever the water took out of your stash during rinsing.
i wouldn't worry about fire during any of this unless you can't go five minutes without lighting up a cigarette. i've done this like fifty times in spaces lacking even an open window and i never had anything to worry about. it's no more dangerous than building a model airplane.
I didn't find the right solution from the Internet.