The problem with alchemists of old, and the techniques you mention, is that these do not change the fundamental atomic structure of the substance in question (ie calcining Lead may give you a Lead Oxide or a different form of lead, but on an atomic scale it is still Lead)
If you want your characters to be successful alchemists then, they need to be able to manipulate matter on a sub-atomic scale, adding and subtracting protons and neutrons to fundamentally trasmute one element into another. In this case you would not need real hands, as they would be far too clumsy and imprecise for this sort of work. So some sort of psyionic hands which could work on a micro scale and delve into the heart of an atom to pluck out a proton could be pretty handy! (you would just need a vast amount of energy to do this, to overcome the strong forces that bind sub-atomic particles together)
Otherwise (if you were being more realistic/practical) you could stick to contained nuclear fission or fusion which is how it's done in nature, transforming Hydrogen in stars into all the elements we know and spewing them into the cosmos
It kind of goes along the lines of having a maiden assistant. 
