After the iron settles out (hopefully with the rare earth elements attached) we need to then separate the iron from the rare earths. Fortunately, in a mixed solution iron prefers ether and the rare earths prefer hydrochloric acid. This means, after collecting the iron precipitate at the base of the pore water bottle, we can redissolve the iron in a solution of hydrochloric acid. Then, with the addition of ether (in a hood- the smell is dangerous!!) the ether will float (its less dense!) on top of the acid and the iron will separate from the rare earths and go into the upper layer of ether. The ether (and iron) can then be pipetted away leaving a much “cleaner” (less iron!) solution of rare earths in acid.