You carefully fill the bottle with enough of the cauldron's ichors for what you consider to be suitably sized sample.
We know that each cauldron employs a different mix of reagents to generate its plague-inducing toxin; likewise, we know that we will need to develop a counter agent that is unique for each cauldron. Your sample from Dalson's Tears will be the key to figure out that cauldron's distinct reagent requirement.
Ah, there is plenty in here for study. Well done, <name>!
For now, the next step is in our hands. We'll need to produce a list of reagents that, when combined with what is already in the cauldron, will act as its counter.
The only way we will be able to introduce this is by placing the reagents into the cauldron directly. Alchemist Arbington will have more information on that, so be sure to speak with him at your earliest convenience.