# Alchemy
 By combining different potions appropriately, common potions of speed, healing and extra healing can be converted to the much more useful full healing and gain ability.
In NetHack, alchemy is the process of dipping one potion into another potion to mix the two into a new uncursed, diluted potion. For those who are not spoiled, alchemy is difficult to learn - there is no in-game indication of which potions are meant to be compatible with each other. While mixing potions at random is generally dangerous and unwise, there are a set of recipes that can be used to produce fairly consistent results.
Despite its name, the alchemy smock has no effect on alchemy.

Contents

1 Description

1.1 Alchemic blasts
1.2 Random alchemy results

2 Stacking
3 List of recipes

3.1 Simple recipes
3.2 Difficult recipes
3.3 Multiple-step recipes

4 History

4.1 Gain level recipe

5 Variants

5.1 SLASH'EM
5.2 Color alchemy
5.3 Blood potions
5.4 Gem alchemy

6 References

Description
The mixtype function describes the alchemy recipes and governs which mixtures of potions produce certain results, as well as how often. Any potion made via alchemy will always be diluted, regardless of whether the input potions were; for recipes, the order of the potions involved does not matter.
The following actions do not constitute alchemy:

Dipping any potion(s) into an uncursed potion of water will simply dilute it; dipping into blessed or cursed water will bless or curse the potion.
Using a potion of polymorph will polymorph the other potion, breaking polypileless conduct.
Alchemic blasts
Dipping a potion of acid or a cursed potion into any other potion, or else 1⁄10 of the time when mixing any other potions, will result in an alchemic blast: The mixture explodes, dealing d10 damage, abusing strength and generating vapors from the potion that was being.[1] This does not occur if you dip into a cursed potion, however.
If an alchemy attempt results in an explosion, only the number of potions actually being dipped will be used up, as opposed to the entire stack.

Random alchemy results
Mixing a pair of non-acidic potions that does not have a recipe (all of which are helpfully listed below) will give a random result:

Your stack may turn into potions of water. (1⁄8 chance, or always if dipping a diluted potion into another potion)
Your stack may turn into potions of sickness. (1⁄4 chance)
Your stack may turn into a random potion type, with the usual probabilities that apply to random potions found in the dungeon. (1⁄8 chance)
All of your potions may evaporate; the one potion dipped into will also be used up. (1⁄2 chance)
Stacking
Dipping one set of stackable potions into another will alchemize multiple potions in the stack being dipped, while consuming only one potion of the one being dipped into:

If the resulting potion (or, for random alchemy, any of the two ingredients) is magical, 3–8 of dipped potions will be alchemized (but no more than the size of the stack).[2]
If the resulting potion is non-magical, or you are performing random alchemy with non-magic potions, at least 7 potions (up to the entire stack) will be alchemized.
Dipping potions into water is not considered alchemy. If you dip a stack of potions into water, all of them will be affected.
As such, some players tend to wait until they have a stack of at least eight potions to dip before performing alchemy, to get the greatest return out of the dipped-into potion; this includes identifying their beatitude and accounting for any diluted potions. Make sure to examine your potions between each dip, to avoid accidentally turning a diluted potion into water; splitting stacks to avoid accidents is unnecessary due to how dipped stacks of potions are treated (as described above).
There are multiple methods to dilute potions: You can dip them into a fountain, or simply dip them in a moat while flying or wearing water walking boots. If neither are available, you can also drop your iron items, scrolls, spellbooks, and other potions, then walk into water - make sure your encumbrance is less than Stressed and that your Luck is not too high, as this reduces the chances of potions diluting.
An altar will identify the beatitude of your potions. If following the atheist conduct, you can bless the potions with holy water; seeing the glow will identify the beatitude. If nothing happens when you dip into holy water, the potions are already blessed; use unholy water to unbless them instead.

List of recipes
Below is a set of tables with a listed pair of ingredient potions and the result that mixing them produces; multiple recipes can yield the same result. Knowing the identity of the potions you are mixing is necessary regardless of which recipes you are attempting; it is also common to informally identify potions by using the output from these recipes.

Simple recipes
These recipes have the greatest likelihood of succeeding (9⁄10, with a 1⁄10 chance of explosion):

Ingredients

Result

potion of healing + potion of speed or
potion of healing + potion of gain level or
potion of healing + potion of gain energy

potion of extra healing

potion of extra healing + potion of gain level or
potion of extra healing + potion of gain energy

potion of full healing

potion of full healing + potion of gain level or
potion of full healing + potion of gain energy

potion of gain ability

potion of fruit juice + potion of gain level or
potion of fruit juice + potion of gain energy

potion of see invisible

potion of fruit juice + potion of enlightenment or
potion of fruit juice + potion of speed

potion of booze

potion of booze + potion of enlightenment

potion of confusion

potion of booze + potion of gain level or
potion of booze + potion of gain energy

potion of hallucination

potion of fruit juice + potion of sickness

potion of sickness

(potion of healing, extra healing, or full healing) + potion of hallucination, blindness, or confusion

potion of water

(potion of healing, extra healing, or full healing) + potion of sickness

potion of fruit juice

Potions of extra healing and full healing are useful to have throughout the game, because quaffing them while fully healed is a common way to increase max hit points. Potions of gain ability are a good way to increase attributes early in the game, but are of little use late in the game when most or all your attributes are already at maximum.
The other recipes are usually not as useful to produce via alchemy, though they may have some use cases:

It is not usually necessary to manufacture potions of see invisible via alchemy; in addition to using gain level or gain energy potions that better serve the previously-mentioned recipes, potions of see invisible are relatively common, and a single blessed potion will convey the see invisible intrinsic permanently.
Potions of sickness can be manufactured without using up other potions that are usually considered more valuable: Fruit juice can be made from amethyst-dipping into booze and cancelling potions of see invisible (typically once you have permanently gained the intrinsic from a blessed potion), and non-lawful players may want a stack of potions for keeping their projectiles poisoned. However, poison resistance on monsters becomes much more common in the late game, although it still has its uses (e.g. against non-resistant nasties such as most of the dragons).
Foodless conduct players in particular can gain a lot from alchemizing diluted fruit juice into booze; both potions give the same nutrition when not diluted (dependent on their beatitude), but a diluted potion of fruit juice only gives half that nutrition.
Difficult recipes
These recipes do not always produce the same result:

Ingredients

Results

potion of confusion + potion of gain level or
potion of confusion + potion of gain energy

potion of booze (6⁄10 chance)
potion of enlightenment (3⁄10 chance)
alchemical blast (1⁄10 chance)

potion of enlightenment + potion of levitation

potion of gain level (6⁄10 chance)
random alchemy result (3⁄10 chance)
alchemical blast (1⁄10 chance)

The potion of enlightenment formula is almost never worth attempting because the probability of success is so low. Potions of gain level are much more worthwhile in comparison due to their multitude of uses, including making full healing potions, and the chance of success is higher than with enlightenment.

Multiple-step recipes
It is possible to use the above recipes in tandem with each other, provided you are careful about the use of diluted potions.
One example is making blessed potions of full healing and gain ability from all those healing and extra healing potions you've collected. You will need to re-stack your potions at all intermediate stages: bless stacks so all will have the same identified BUC status, and dilute concentrated potions so they will stack with the newly-alchemized ones. Follow the route:

healing → extra healing → full healing → gain ability
Only the first step can be done using a potion of speed; the rest need gain energy or gain level (see image at the beginning of the page). Leave over enough full healing, and bless all the end results.

History
In NetHack 3.4.3 and earlier versions, including some variants derived from these versions, alchemy always acts on the entire stack.
Starting in NetHack 3.6.0, alchemizing a stack works differently from 3.4.3 and from later versions of vanilla NetHack:

If you dip 10 or more potions, 2–9 of them will be alchemized.
If you dip 2–9 potions into a non-magical potion, all of them will be alchemized. The following potions are nonmagic: water, oil, acid, fruit juice, booze, and potion of sickness.
If you dip 2–9 potions into a magical potion, at least 2 will be alchemized, up to the number of potions dipped.
In versions prior to NetHack 3.6.3, the case for dipping healing potions fell through to the unicorn horn case due to a missing break statement, causing the combination of healing and sickness to alchemize to fruit juice, and the combination of healing and hallucination, blindness, or confusion to alchemize to water.[3][4] This behavior was made explicit and intentional in NetHack 3.6.3 via commit c6b75407.

Gain level recipe
A very complicated recipe is used in 3.4.3 for making lots of potions of gain level:

 Stack of water → sickness → fruit juice → booze → confusion → enlightenment → gain level
Gather lots of potions, turn them into water, and dip the stack of water (blessed or uncursed) into some potion.
This counts as random alchemy; 25% of the time you will get potions of sickness. The other times you may lose one potion of water, or get some other random result. In those cases, just dip again unless you get something good from the random result.
Cancel the sickness or dip a unicorn horn to turn it into juice, then dip juice into speed for booze.
Dip booze into enlightenment for confusion, and dip that into gain level or gain energy for a 1⁄3 chance of enlightenment (the other 2⁄3 they become booze, which moves you back a bit.
Dip into levitation for a 2⁄3 chance of gain level; the other 1⁄3 gives a random result, and probably means you have to start the whole thing over again.
In 3.4.3, this recipe uses up an expected 23.67 potions, including all the trackbacks and alchemic explosions; to conserve resources, you can dip the water into otherwise useless potion of acid, and use a unicorn horn or cancellation spell to convert sickness to juice rather than a wand of cancellation; 3.6.1 makes this recipe much less profitable. Firstly, producing sickness through random alchemy incurs a 50% chance per dip of the entire water stack disappearing, which makes it significantly more risky (and costly on average). Secondly, both confusion and enlightenment are magical potions, so making them in decent amounts under the new stacking rules is significantly harder. Assuming a large potion supply (at least 8 for each dip) and accounting both for dipped-in enlightenment and byproduct booze, each potion of enlightenment on average requires 5.1 potions of booze and 1.9 potions of gain level or gain energy to make, which actually makes using gain level counterproductive. In a more realistic scenario of limited potion supply, you have a very real possibility of using up all of your gain energy potions and ending up with fewer enlightenment potions than your initial supply.

Variants
SLASH'EM
In SLASH'EM, dipping into a cursed potion will cause an explosion.
Dipping a potion of water into another potion is the same as dipping that potion into water; thus it is not possible to use potions of water in random alchemy, as it will always dilute the other potion rather than creating a random alchemic result. This can be circumvented by taking the potions of water and dipping them into the castle moat, turning them into potions of amnesia. These potions can then be used for random alchemy, but the vapors caused by an explosion will cause you to forget spells, items and levels, unless you are polymorphed into a form that is eyeless and have breathlessness from any source, including your polymorphed form.

Color alchemy
The Color Alchemy Patch, notably incorporated in UnNetHack 3.5.2, changes the rules of alchemy to be based on artistic color mapping. It makes use of the primary colors red, blue and yellow, the secondary colors orange, green and purple, and the tertiary color brown, as well as black and white. All primary, secondary, and tertiary colors have a light and dark variant:

Color
Light
Dark

Red
pink potion
ruby potion

Blue
sky blue potion
indigo potion

Yellow
yellow potion
golden potion

Orange
orange potion
amber potion

Green
emerald potion
dark green potion

Purple
puce potion
magenta potion

Brown
ochre potion
brown potion

Mixing potions together gets the following results:

Ingredients
Result

red + yellow
orange

red + blue
purple

yellow + blue
green

any two secondaries
brown

any dark potion + white
corresponding light potion

any light potion + black
corresponding dark portion

black + white
gray

any other combination
random alchemy result

Mixing two light potions will create the light version of the result, and the same goes with dark. Mixing a light and a dark potion will create either result at random unless one of the original potions is diluted, in which case the result will have the same light/dark level as the undiluted potion.
These potions are considered colorless:

bubbly        icy           smoky
cloudy        luminescent   soapy
dark          milky         sparkling
effervescent  muddy         squishy
gooey         murky         steamy
greasy        silver        swirly
fizzy         slimy         viscous

The patch also changes three potion names: purple-red, brilliant blue, and cyan are replaced with amber, indigo, and viscous.
Because there are 12 more possible potion colors than types of potions in the game, some colors will probably not exist, rendering some formulas unavailable for certain games.
If the desired color is not a color used in the game, both potions will be wasted. For example, if you mix an orange potion with an emerald potion, but brown potions are not used in your game, then you will both potions disappear, leaving you with nothing: "The mixture glows brightly and evaporates."
Finally, a potion of polymorph, regardless of its color, will simply polymorph anything it is mixed with.

Blood potions
Potions of blood and vampire blood, introduced in SLASH'EM and UnNetHack, are also subject to alchemy:

Ingredients

Result

potion of fruit juice + potion of blood

potion of blood

potion of fruit juice + potion of vampire blood

potion of vampire blood

In UnNetHack, these are the only potion-mixing recipes outside of the color alchemy system.

Gem alchemy
In SLASH'EM and dNetHack, dipping a valuable gem into a potion of acid will generate another type of potion. The potion you get is defined by its randomized description, not by its identified description. For example, if you dip a ruby into acid, you will always get a ruby potion whether ruby potions are full healing or hallucination in your game.
There's a chance that dipping will cause an explosion, using up the potion and gem and dealing some damage. If the potion of acid is cursed, it always explodes, like with normal alchemy. You will need one potion of acid per potion produced; stacks of gems will be melted one gem at a time.

Dipped gem

Resulting potion appearance

dilithium crystal

(always explodes)

opal

cloudy potion

ruby

ruby potion

garnet

pink potion

jasper

purple-red potion

jacinth

orange potion

agate

swirly potion

citrine

yellow potion

chrysoberyl

golden potion

amber

brown potion

topaz

murky potion

emerald

emerald potion

turquoise

sky blue potion

aquamarine

cyan potion

jade

dark green potion

sapphire

brilliant blue potion

amethyst

magenta potion

fluorite

white potion

black opal

black potion

jet

dark potion

obsidian 

effervescent potion

worthless glass

(no effect)

There are no gems that produce milky, smoky, muddy, fizzy, luminescent, puce, bubbly, icy, blood-red, or clear potions.
As in vanilla NetHack, dipping an amethyst into a potion of booze turns it into a potion of fruit juice.

References

↑ potion.c in NetHack 3.6.0, line 1887

↑ potion.c in NetHack 3.6.1, line 1963

↑ src/potion.c in NetHack 3.6.2, line 1766: Note the lack of breaks in the cases down to the unicorn horn case

↑ src/potion.c in NetHack 3.6.3, line 1795: Newly added fall-throughs are marked via comments

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