The recipe for eolith temper will be in volume 10 of the scholar tradeskill books. If you aren't a scholar, you'll have to buy apothecary volume 1 from your wholesaler to make it. (Before you buy the book, examine it to make sure the recipe is in it; I'm not positive it's volume 1.) Anyone can use apothecary once they've gotten to tradeskill lvl 10; it's one of the intermediate skills introduced to remove interdependencies. You should have apothecary buffs in your knowledge book. And don't worry if it's really hard to make 4 tempers at a time at first, because your apothecary skills will probably be very low.