And another crunchy bit from my campaign, which due to heavy use of rule terms has been typed straight in English...
Shoot me what you think of it and where you see potential trouble, especially as this is an instance where I bend the FtA! system around a lot.

Notes:
#1: These rules are interconnected with a houserule of me, the Ale&Wenches rule with heavy inspiration by Jeff Rients. These allow to blow money for XP, and so it has been important to keep potions cheap. Elsewhise, the choice between 300GP for a one-shot healing potion or 300GP for a good and lasting step towards the next level would have been a bogus choice. (One-shot items will also be elsewhise cheaper for the same reasons.)
In RAW games, where money is an XP-independent resource, I'd go with 300GP as base price (the regular potion sale price according to FtA!GN!), and also strictly enforce the "maximum gold for magic items in settlements"-rule to avoid cheap and riskfree money-farming strategies.

#2: Time limits are also interconnected with my campaign frame - a Western-Marches-like game with short sessions with a fixed ending for a rotating roster of players, and downtime as a clear-cut line between sessions. For more fluid time management, you'll have to come up with your own time constraints, or play time as constraint down if you use gold as the main constraint for alchemy (see #1).

#3: This subsystem also assumes that alchemy is in that setting a pseudoscience, where discoveries are made by either stumbling over them at random, or by copying what others have found out (therefore the roll on the random table, or the need for a sample to research particular recipes).
If you go with a more systematic approach that allows to research purposefully for new recipes, you'll probably need to weigh the potions, their effectiveness and their resulting price, and maybe also attach level/attribute limits similar to spells to certain recipes to avoid bogus choices - and you'd be on your own there.

#4: This subsystem references Labyrinth Lord's Random Potion Table rather than the FtA! Random Potion Table, as the first one is simply longer and more colorful. You'd be on your own if you'd want to run it with the latter (and IMHO such an alchemist wouldn't be fun, as the list just contains six run-of-the-mill potions).
At the moment, LL potions will be converted on-the-fly to FtA! stats whenever I need to. One day, when I feel less lazy and have less important prep work to do, I might go over the whole LL list and convert it. As of now, this possibility seems far away (especially as I have yet to whip up the 8 levels for the starting region's biggest dungeon Witch Fortress).


General
Alchemy is treated as a Spell List and can be bought the same way by Wizards.
Whenever you learn a new "spell" on this "list" (either as a Wizard's auto-pick or by investing skill points), you learn d6 recipes (determined randomly on LL's Random Potion Table), and gain one sample of each as the byproducts of the research (yes, that's how your freshman alchemist with his pathetic d6GP has something tangible from his knowledge from level 1 on).
If you roll a recipe that you already have, you instead achieve a break-through in that particular recipe, either doubling the amount of potions createable per ingredient (and so effectively halving costs), or lowering the DC to create the potion and to find the ingredients for it by 5. This may happen several times, each time lowering the DC and/or the price.

If you have an existing potion, you might also analyze it to learn exactly that one recipe. This will destroy the potion, but it will be a guaranteed result in your d6 roll. Per learned alchemy "spell" only one potion might be analyzed, and analyzing can only be used to learn a new basic recipe. Break-throughs can't be achieved that way, and even if the potion in question has been an improved version, your analyzing will only do enough good to get some basic clues.
Skill points "banked" for spell purchase might also be used to analyze potions.

Alchemists might also learn basic recipes from other alchemists, with the same procedure and with the same cost as new spells are learned.


Getting your ingredients
Ingredients might either be bought in settlements, or searched for in the wilderness. Either can only be done during downtime, as it's time-intensive and doesn't go well together with traveling or adventuring.

If you go with the buying scheme, during each downtime you'll find only enough special ingredients to create 2d6-11 potions in hamlets; in villages d3-2, in towns d3 and in cities 2d6. (Megacities as Diablo's Point in The Setting might give you much more opportunities at the GMs discretion, although the prices will probably likewise skyrocket.) They will cost you 50GP per pop.

You might also traverse the wilderness for this purpose in your downtime and make an ACT INT check DC 25 supported by Herbalism Lore, Nature Lore or Wilderness Survival, or DC30 supported by Occult Lore. If successful, the remaining wilderness of a settlement hex will grant you d3-2 ingredients, wilderness hexes adjacent to settlements d2-1 ingredients, civilized hexes d3 picks, and uncivilized hexes 3d3 picks. (Of course, you have to end up on such a hex when the session ends to get the high rolls - and probably alone, as your friends will most likely prefer to stay in town and blow their money for ale, wenches and XP. So, good luck with random encounters and other wilderness dangers if you want to get to the good spots.)
Some special wilderness hexes (like those containing standing stones or druid's groves) will grant more at GMs discretion, but there will certainly also be some druids, fairies or other self-proclaimed "guardians" who don't enjoy watching how "infidels" rob their "holy" place.


Brewing potions
To create a single potion, an alchemist lab (500GP) and one pick of ingredients per potion are needed. It must also be done during downtime (but can be combined with buying or searching ingredients, as well as ale&wenches if you stayed at the settlement).

Roll for each potion an ACT INT Herbalism Lore DC20, or Occult Lore DC25. This will either get you a functional potion, or it will turn your expensive Zhodabatian naga tooths and that four-leaved clover wrestled from the dead cold hands of the archdruid into horribly tasting drinking water.

A triple 6 means not just success, but means another breakthrough (d3): 1: you find a more ingredient-efficient way to brew the potion, resulting in two instead of one potions immediately and a 50% cost cut in the future; 2: you find an unthought angle to optimize that particular brewing procedure, lowering the DC to find the ingredients and to brew that potion by 5; 3: as with Penicillin, a accidentally wrongly treated waste product of the brewing turns out to be a new potion for you, or an easier creatable version of a potion already known to you, granting you a random extra recipe.

A triple 1 means not only a screwed potion, but also a roll on the Craptastic Chemical Catastrophe Chart (3d6):
3 - Grim Reaper Screwdriver - PAS CON 30, or that sudden cloud of toxic, acidic, mutagenic, carcinogenic, boiling, ignited, radioactive and generally unhealthy fumes leaves only your ash-filled boots of you.
4 - Dottore Chiagglis House Special - Spirit-lifting fumes part all evil from the alchemists soul. Unfortunately, all evil decides to stay and to form an inner demon, which tries once a day at the worst possible moment to possess the character. If he doesn't make a PAS WIS 20, his body, mind and soul transform for 2d6 hours. During that time, he's out of the player's control, and the GM will determine what degenerate and horrible acts he'll perform.
Roll d6 for your particular inner demon: 1-2 - Herr Heide: An ugly brute (CHA-1, INT-1, STR+1, CON+1, neither spells nor alchemy, but melee +3) who's all for beating up orphans, throwing widows from bridges and other ultra-violent ways to make a boring afternoon fun; 3 - He-who-eats: A fat dude (CON+1, DEX-1) who can never get enough, wasting d6*10GP per hour (and not fearing going into debt), wasting an equivalent amout of equipment if there's no way to spend money, and wasting other peoples stuff if his host doesn't have anything left; 4 - Jack the Gipper: Looks and acts exactly like the character, but lies about every question (+10 to lie undetected, resist truth spells etc.) and will also make up wrong claims if there is no question to lie about, preferably so that others get damaged; 5 - Sükkübüs: This seductive female demon sets CHA automatically to +6 and has access to the Nymphs gaze power, as well as Telepathy d6 and Witchcraft 3 as natural spells used with ACT CHA Occult Lore, but no other magic (including the host's). She indulges in kinkyness, adultery and general debauchery just as her name implies, and unlike other inner demons, even after she's gone her host body keeps her shape for another 2d6 hours, without the powers, but with all the caused trouble linked to that pretty face; 6 - Dot the Douchebag: A were-swine who acts like all were-swines do, but extra obnoxious.
5-6 - DIE on organic poison gas! - The potion does not only turn out ugly, it produces toxic fumes, requiring three PAS CON checks DC20 to avoid losing d6 CON each time.
7-8 - He's on fire! - 1d6 damage immediately and each following round, PAS DEX 15 per round to extinguish.
9 - Allergic reaction - Those damn fumes trigger an yet unknown allergy, giving the alchemist a d6 penalty on all rolls that decreases each day by 1 until that dripping nose, itching skin and blains size of a gold piece are gone.
10-11 - Sickness - Sickening fumes give the alchemist a d3 penalty for one day.
12 - Wow, look at those COLORS! - Interesting fumes carry the alchemist's mind directly to the Wonderland of the Bizzaro Shroommaster of Oz, where pink elephants, white mice and speaking polearms dwell. He's Stunned for the first d3 days of the next adventure.
13-14 - Acid - An unexpected splash of alchemist dissolvent does immediately d6 damage and each consecutive round, until a PAS DEX 10 allows you to slip from that clothes and into the next body of water. No matter what, all your non-acid-proof possessions (including armor, weapons, clothes, money) are gone for good.
15-16 - Ogremage Hulksmashs Choking Grip - Foul and breath-taking fumes fill the whole area, forcing you to use the drowning rules for d6*d6 rounds until they perish (and you probably with them).
17 - Wow, I just invented combustioOOOOM! - d6*d6 damage, PAS DEX 25 halves as you jump under that table last minute. Oh, and hope too that this inn room hasn't been THAT expensive...
18 - Wazzat? Wazzat? - That potion has an unexpected smell and look, but it yet seems to be potent. The GM rolls randomly for the effect, but the actual effect can only be found out the hard way.


Alchemy "Spell List" and it's role
The Alchemy "spell list" is typically known to Rogue-Wizards, who either work as apothecarians, doctors or support personal for wizard's colleges in cities, who travel as snake oil salesmen through the civilized realms, or who serve druidic or tribal communities in remote areas as herbalists or healers.
Fullblown Wizards use it more rarely, although some enterprising (or coward) wands-for-hire use it to expand their palette of magical services with effects that are also useful out of town (or in a way in which the wizard can stay out of harm's way with the gold safely banked away).
Finally, Warrior-Wizards are the most rare to find use for such a kind of lawn-chair magic, although in tribal societies there are berserkers, who boost their own combat prowess and brutality with herbs and drugs. Occassionally, there's also the pragmatic druidic ranger who finds turning nature's gifts into tangible benefits more useful than talking to them, or the smart city thug who uses a stolen grimoire, lab und drugs to bring his brute force on par with fully trained warriors.


Ice-Elvish cuisine (campaign-specific)
The Ice Elves[1] from the polar north of the Kopikala world use Alchemy in an unique way. Rather then mixing stomach-revolting oddities into drinks tasting like cod-liver oil, they use rare delicatessen to bake cakes and pastries with special properties.
This makes them not just more useful allies to the northland traveller and more desirable gift bearers to the northland dweller - it has also the unfortunate effect that Ice Elves are much sought-after slaves, who can at the same time serve as slave girls and boost the power of their owner.

Ice Elves with the Alchemy "Spell List" need only a cooking kit instead of an alchemy lab, and use ACT CHA Craft: Cooking to create their "potions" (applying their racial Craft bonus for nice but useless knickknack and candy).
Ice Elves with the power of "Festtagsessen"[2] may use it in lieu of wilderness search to create ingredients; a successful use of PAS CHA Perform: Jingle Bell[3] DC25 creates d6 viable ingredients per downtime. The DC reduction for break-throughs applies here as well, as the Elve learns what taste to look for for which effect and how to create it, so lowering the number of mundane bakery duds per magical real deal.

[1] Basically reindeer-riding ice dryads who dress like Santa's Little Hookers, travel south during winter solstices to mate with humans and have the nature powers you'd expect (using mistletoes to calm foes, flying with sleighs etc.)
Yes, they're a viable PC race, and no, I game neither for escapism nor for gonzo fun, solely for the artistic value deeply hidden in the description above.

[2] "Feast", the power to fill empty boots with candy and tropical fruits.

[3] To work magic and/or natural powers, elves in my campaign world use performances with appropriate musical instruments (instead of occult lore), and likewise CHA supplants WIS for this purpose.

Very interesting.  I could see halflings having the "ice-elf" variant instead, in other campaigns.

RPGPundit

Yes, that bakery/cooking option could easily be used for other groups of alchemists as halflings, witches, druids etc., depending on the campaign frame, similar to the way that bards and druids are a bit separated from regular spellcasters in RAW FtA! by their different prime attribute.

Other relatively useless skills might work as well, as Nature Lore in a more renaissance setting where Alchemy is an actual protoscience, in contrast to less rational "regular" magic.

On the other hand, Herbalism Lore as the default skill might easily be replaced by Occult Lore in games where alchemy should just be another expression of "regular" magic, without any separation.

(I think this is generally one of the points where FtA! shows the greatest and most elegant adaptability to reflect special campaign frames.
Just by replacing (mental stat) for (mental stat) either as prime attribute, quick-casting attribute and/or actual casting attribute, and/or by replacing (relatively useless skill) for (relatively useless skill), certain magic schools can be more separated and flavoured, to a differing degree.
It reminds me a lot of the way that SR4 and SW separate different magic styles, although this is probably just a parallel development. Especially as the seeds could be tracked back to D&D's cleric with his Wis for Int.)