How many weapons can I coat with the 1/2 ounce of basic poison from an alchemy jug?

Question

One of the the liquids than an alchemy jug can produce is 1/2 ounce of basic poison. However, there is no indication in the item's description of how much you can do with this amount of poison. In the description for a poison vial, it says you can coat 1 weapon or 3 pieces of ammunition with the poison from one vial, but it doesn't say how much poison comes in a vial. So, is the half ounce of poison from an alchemy jug intended to be equivalent to one vial? If not, how many weapons or pieces of ammunition can be coated using the half ounce of poison?

Answer 1

There are no numbers given for how much poison is contained in a vial of basic poison, how big that vial is, or how much a single "dose" of poison is so it's hard to say with 100% certainty and ultimately comes down to DM ruling.

Option 1

A vial from the equipment list can hold up to 4 ounces of liquid (PHB, pg. 153).

Assuming a vial of basic poison contains a full 4 ounces of poison, then this gives us 25% weapon coverage per ounce of poison (or 12.5% per half-ounce), and 75% coverage on 1 piece of ammunition per ounce (or 37.5% cover on 1 piece of ammunition per half-ounce).

In short, you wouldn't be able to cover even one piece of ammunition, let alone one weapon, with the half-ounce of poison the alchemy jug produces and it would take you at least 8 days to produce enough poison to fill a vial.

Option 2

However, page 139 of the DMG states that:

Most potions consist of one ounce of liquid.

Basic poison isn't a magic item or a potion but it is clear that a 4 ounce vial isn't the standard liquid container.

If a vial of basic poison is only one ounce then you could cover half a weapon or 1.5 pieces of ammunition and would only take 2 days to gain enough poison for full coverage.

Option 3

Option 3 is to keep it simple. Don't get bogged down with unnecessary levels of finicky detail trying to figure out how many ounces are in a single dose of poison; the designers sure didn't in this instance.

If we keep things simple then the half-ounce of poison produced by an alchemy jug is equivalent to and follows the same rules as the vial of basic poison.

Answer 2

I think your first instinct is the correct one: the half-ounce of poison is a single dose, suitable for the standard one weapon or three pieces of ammunition.

How many ounces are there in a vial of poison? While "a vial" is an intentionally vague amount that could range from several ounces to just a bit of fluid, we can use weight to put some limits on it.

In the Player's Handbook, there are a small number of items with listed weight under a pound, which is of course 16 ounces. The smallest is the piton, at 1/4 pound, or 4 ounces.

Since a vial of poison has negligible weight, at most it must be somewhat less than 4 ounces in total -- and that includes the glass, stopper, and fluid together.

I don't think it's possible to narrow it down much more than that from weight.

But, logically, a vial of poison really can't contain multiple ounces of fluid, or it would be able to coat much more than three arrowheads (or one blade). Even accounting for waste, half an ounce seems like a reasonable amount of viscous fluid to smear on a handheld object without dumping it all over the place or having a lot of poison left over.

Answer 3

You are making this way too complicated. A basic poison does a minimal effect, most creatures are resistant or immune to it.

You can use the poison in this vial to coat one slashing or piercing weapon or up to three pieces of ammunition. Applying the poison takes an action. A creature hit by the poisoned weapon or ammunition must make a DC 10 Constitution saving throw or take 1d4 poison damage. Once applied, the poison retains potency for 1 minute before drying

The players can harvest this once per day. Let them build up an army of the stuff, if they take their action to apply the poison in the middle of a battle, then that is one less attack against a monster. It will be balanced out or potentially hurt them.

Answer 4

Poison, especially with regards to the Alchemy Jug, is a hold over from first edition. There really haven't been any significant updates to it since then, unfortunately.

In first edition, poison was largely restricted to evil characters and somewhat discouraged for players (see page 107 for the 1e PHB). And in the sections of the 1e DMG guide for "blade venom", an insinuative poison (1e edition had different types of poisons for assassins to choose from), there is no mention of the volume necessary to coat a weapon. The only reference to volume was specific to "grenades" of poisons (see page 64 of 1e DMG), listed as 4oz, and meant for splash damage. Blade venom, in 1e, was more potent and dangerous than it was in 5e, causing more damage and lasting longer on the blade (up to 3 days iirc) but was also restricted to high level assassins for manufacture (see pg 20 of 1e DMG)

The alchemy jug itself comes from 1e (see page 137 of 1e DMG) and has mostly carried over, almost verbatim, to 5e including the volumes and types of liquids it can output (chlorine is strangely missing in the modern version).

Poison, as a mechanic for players to use, is more discouraged for players now than it was then. There is less discussion about the morality of using poison, but it is, basically, removed and forgotten as a mechanic.

I take all this to mean that the Alchemy Jug was likely intended, in 1e, to provide one dose of blade venom or equivalent and that grenades of poison meant for splash damage were expected to hold 4oz which is what we have as our basic (4oz) poison in 5e.

As a DM, after researching this, I would rule that for a vial of poison to be an effective improvised thrown weapon, it must be a full 4oz but it would contain 8 doses of "blade venom" for poison a weapon or ammunition.

Edit:

Realistically, it doesn't matter, if your players have a single dose of poison they can apply precombat, you're talking one hit with a single, saveable, 1d4 damage otherwise they sacrifice action economy (without the poisoner feat) and lose out on a whole lot more damage. Even with the feat and an unlimited amount of poison for all combats, they'll be pushing less damage than other feats (like PAM, etc.) Basic poison just isn't very good in 5e. The poison made with the poisoner feat is much more potent (2d8 DC14 vs 1d4 DC10 and gives the poisoned condition)

The second concern would be selling the poison they pour day over day. But even then it isn't very worrisome as it equates to 6.25g per day assuming they can find someone to sell it to. If your player is out for a few weeks, gathering poison, and you feel that the hundred or so gold is going to be game breaking, have him arrested for selling an illegal substance. The abuse of the item creates its own content.