L tartaric acid 700 grams , 1 liter Freebase and 1,4 liters Destilled Water . You have to stirred very very strong after two minutes its precipate a solid L meth tartarate , after that you have to separate the solid from the aquas layer with a buchner funnel with vacuum , in the aques layer is the D meth you have to basified if with NaOH . If you have the right equipment its easy , if you do it with d tartaric acid the d meth will be in the solid , you have again to separate it in the buchner funnel and dissolve the d meth tartarate in water , water again basifiyed with NaOH . You have first to dissolve the Tartaric acid in the water and after that put the freebase in the dissolved tartaric acid its a exothermic process , in small amount its ok for inside in bigger amounts its better you do it somewhere outside.
