Alchemy

If you #dip one potion into another potion, and neither potion is a potion of water or potion of polymorph, then you are performing alchemy. If it goes well, the two potions will mix into one new potion. For those who are not spoiled, alchemy is difficult to learn.

Though most of the effects of alchemy are dangerous or unpredictable, a few specific recipes are worth it: you can use potions of gain energy to upgrade your potions of healing and extra healing. You can also use potions of gain level for those upgrades, if you need not gain levels.

Danger of alchemic blasts
Even if you are following the recipes, there is a 1/10 chance of an alchemic blast. Further, if you dip a potion of acid or a cursed potion into another potion, you will always cause an alchemic blast. The mixture will explode, the blast will take 1 to 10 HP from you, and it will generate acid fumes (whether or not acid was an ingredient). The acid fumes will abuse your constitution.

Recipes
The potion.c function decrees the alchemy recipes in this game. Each recipe requires you to mix two potions. The order of potions does not matter: whether you dip a potion of healing into a potion of speed, or dip a potion of speed into a potion of healing, you will make a potion of extra healing (with the 1/10 chance of an alchemic blast instead).

In the below tables, the result is on the left and the ingredients are on the right; sometimes there is a numbered list of multiple recipes. Try skimming the left column for the potion that you want to make. All potions in the tables do link to their articles.

Simple recipes
These recipes have the greatest likelihood of succeeding. 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 your attributes are already at maximum.

It is not usually necessary to manufacture potions of see invisible via alchemy, because potions of see invisible are relatively common anyway, and a single blessed potion of see invisible will convey the intrinsic permanently.

Difficult recipes
Some recipes do not always produce the same result. The chances below add to 9/10 because there is also a 1/10 chance of alchemic blast. The potion of enlightenment formula is almost never worth attempting because the probability of success is so low. Potions of gain level, however, are often worth obtaining via alchemy, because they are more useful than the potions used to make them, and the chance of success is higher than with enlightenment.

Mostly-useless recipes
Only in rare cases would you ever use these recipes, since you're using up some good potions to make bad ones. For example, maybe you really need a potion of booze to confuse yourself, or potions of hallucination are smoky potions in your game. Most players, however, would find these recipes useless:

Random alchemy results
If you perform alchemy on two potions that do not have an otherwise defined result, and you did not dip into a potion of acid, then NetHack will give you some random result:


 * You might make a potion of water. (1/8 chance, but 1/1 chance if dipping a diluted potion into another potion)
 * You might make a potion of sickness. (1/4 chance)
 * You might make a random potion, with the usual probabilities that apply to random potions found in the dungeon. (1/8 chance)
 * You might evaporate and waste both potions. (1/2 chance)

Do not

 * Do not involve any potion of acid in alchemy.
 * Do not dip a cursed potion into anything; it will cause an alchemic blast! (Dipping into a cursed potion, however, is no different from dipping into an uncursed potion, and in fact is a good way to use up a cursed potion.)
 * Do not involve any unidentified potions in alchemy; you need to know the identity of both potions to use the recipes. Identifying input potions through alchemy is not feasible because of the high chance of random effects. (Identifying output potions, on the other hand, is quite common and often useful.)