I saw Salman ibn Arammay within the worshops again. He has not ceased his toil over the perfection of his methods, this that he calls the 'cleansing' of metals. He has about him all manner of grotesque and strange materials he tells me is some kind of bronze or iron. Some ooze on the floor and others crunch underfoot as glass from the blowers' shops in Alexandria.
I must hope that this passion of his pays off, for he is a good man.

From the story of Salman the Cleanser, as told by his friend

Alchemy is all about transformation, purity and refinement. Of course, to purify and refine a thing you have to understand how it works, which is what advancing as an alchemist is all about: perfecting your understanding of the workings of animals, plants, people, and finally the soul itself.

The practice of Alchemy can take many forms. It is considered more of a Science than Magic by the Arabs of North Africa, and is more methodical and academic than its practice in the Easter Roman Empire. The laboratories in which an Alchemist might work can range from simple, disorganised shacks, to specially-built palaces of alchemical production.

Contrary to popular beliefs and the many jokes about Alchemists, they are rarely without eyebrows or in a state of some explosion. The requirements of Alchemy demand experimentation and eventual precision, but the determination to succeed counts for much.

It's in the nature of alchemical process that it doesn't scale up. It's not just a case of automating the production line so that you've got five people mixing the tears of a virgin into your gold dust; you need to make sure that each of those five people know the significance of mixing a virgin's tears in this way, that they've read and appreciated the Five Primary Texts arguing for and against the symbology of virgins' tears in the recipe, and that they've themselves personally undergone the experiences you've undergone to learn the recipe.

But you can make some small savings which will let you make quantities larger than the amount described here. To do this, you will need to spend extra AP on the recipe and have a healthy level of Administration. The end result still won't be quite as good as an alchemical production you've single-handedly made – time and effort and personal attention count for a lot in this discipline – but an army outfitted with True Steel armour (which, by the way, will take Administration 5 to pull off) will still have an edge over another army.

The Alchemist is capable of 'purifying' various objects, such as metals, liquids and so on. This has the effect of enhancing the effect and properties of that object, this can have the effect of also enhancing the less attractive qualities of the material. A more skilled alchemist (once you have learned a tier 2 spell) can all but eliminate some of the unfavourable qualities.

A common form of purification is performed on iron:

From the wood of a tree struck by lightning, iron ore that has been kept out of sunlight, the blood of a man who has killed, and snowmelt you can transform a thing made of metal into True Steel, a blue-grey metal that is light, hard, and keeps its edge indefinitely. It's very much in demand for weapons and armour. 2AP produces enough for one sword, one suit of armour, or any other similar quality.

From the yellow bile of a madman, sulphur mined at midday, tar taken from a tree grown in a mixture of three different earths, and the salt from a cat's tears you can make Alchemist's Fire, a strange liquid fire that can be stored within clay pots or glass jars, burns even without fuel, sticks to the things it touches, and doesn't go out unless doused with a large quantity of earth. Alchemist's Fire doesn't spread as effectively as regular fire does, but it is considerably nastier. 2AP produces enough to easily firebomb a building.

The water of life, a pure essence capable of healing the most grievous wounds. Can usually restore the flesh of anyone who drinks it unless they are actually dead and will not affect ailments or diseases, nor cure birth defects.

You can combine different elements to create powders or potions of some limited effect. By refining parts of the elements, stripping away with other elements their less useful parts, you are increasing the essential (in the sense of a pure essence) powers of those elements. These range from flash-powders to potions that brighten the mood.

You have reached the apex of your art. You can change the substance which pretty much any physical object is made out of. Turning lead into gold, chalk into cheese, and living flesh into unliving stone are all within your remit.

The water of death, a pure essence capable of aging and rotting the body. Though not necessarily lethal, the potion will deaden any body, making it more fragile. It has been rumoured that such alchemies may even animate long-dead flesh and bone. They bear a mechanical resemblance to who they were before, their soul is lost forever.

Divine: The Philosopher's Stone: Grants immortality (immunity from ageing and disease, not from swords).

Ancient: Chimera: Recombining and changing animals. Making your mythic animals.