Next time, you could do it like this: melt your stuff til liquid, let cool a bit, and add dry acetone. Now cover with sum foil, place in fridge and wait. Overnight is great (hard, I know
). There should be white crystals growing out of your molten stuff on the bottom. Sometimes they also appear directly when you add acetone - then cool anyway!
When you can't see the molten stuff anymore, it is finished: stir a bit, filter the whole thing into fine coffee filters and rinse with cold dry acetone. Let dry like usual. If there is still molten stuff on the bottom, repeat the whole thing (add acetone, cool overnight, stir and filter off goodies).
There ya go.
To the others, doubting this little reXtal method:
Meth HCl will melt at lower temperatures when it is cut. Also it will hardly recrystallize when you just cool this melt (impurities, you know). It stays liquid. A solvent with low solubility for meth*HCl (like alcohol) facilitates crystallization (you know too). And there are earlier reports of reXtalizations from acetone, search the old hive for a thread with pictures of huge clear crystals and discourse on how to grow them. IPA just allows for a quicker crystallization - as for a quick crystal formation, the substance should ideally have a high solubility. Meth HCl is almost insoluble in pure acetone, therefore the process takes a long time in acetone alone. Through adding a small amount of IPA, the amine hydrochloride molecules have more ease to rearrange to the desired crystalline structure (white solid kickass meth
)
So far on the theory; and believe me, it works exactly like he wrote (although he made some mistakes like "nonpolar"..) - I know this kind of reXtalization well. Works also fine with Et
2O/acetone, and bonus: eventual water traces will form a small bottom layer, which can be easily separated and flashed with dry acetone, too - makes beautiful glistening flake-like crystals from ether (and not-as-nice ones from the tone flash if done).
(try it and you'll see - but of course only if you are experienced with ether!)