wolfx: What you just said makes no sense. What is true is that you cannot precipitate the HCl salt of MDMA simply by adding concentrated hydrochloric acid to it - the salt will just dissolve in the water. Use a dilute solution of the freebase in a suitable solvent, then add dry HCl as an alcoholic solution or even better dissolved in ether. You can also gas the freebase solution with anhydrous HCl gas.
dr_ruthenium: The carbonate is not stable, it may easily revert back into the freebase in case the CO2 evaporates (due to heat for example).