Alkahest, or Alchemical Solvent, called by the vulgar simply, 'acid.'
A combination of corrosive juices are gathered together, some from animals
(cattle are preferred, for their large and multiple stomachs, but they must
be concentrated and rendered more potent, and some prefer to use the digestive
juices of carnivores, which requires much less fluid volume and preparation)
and some from rare swamp-dwelling plant life (so-called 'carnivorous' plants,
such as the pitcher plant, are required, while many other plants produce caustic
or corrosive materials, the use of these will actually *negate* the other ingredients
efficacy and ruin the preparation!). These various acidic solutions are boiled
and refined down to a paste, while, in a separate container, hundreds of ants
(or termites, I have heard, although I have not attempted to use them myself)
are ground up into a sticky gruel. Finally, the residual pastes from the three
separate sources are combined together in a ceramic container, and mixed with
powdered sulfur. The whole then steeps for a day, under gentle agitation (spinning
the container, instead of shaking it, is advised, as the too much agitation
can have explosive results), until the resultant concoction is a pale yellow
oil with two fingers-width of brownish sediment coating the bottom of the container.
At this point it is ready for use, and when agitated, forms into a bubbling
bright green fluid for a few moments, before settling back down into the yellow
oil / brown sediment state. Used as a flung weapon, it is traditionally shaken
once (to agitate the mixture) and then flung at it's target. (This step is not
strictly necessary, as the process of throwing it, and it's impact should be
adequate to sufficiently agitate the fluid...)
A note, from a former apprentice's point of view. Under some, less than kind,
tutors, apprentices and lowly workers are assigned to render down these various
corrosive compounds in sealed rooms, where the fumes of these substances damage
both their lungs and permanantly scar their eyesight. When they are too blind
to work, or begin coughing up blood, they are put out onto the street and replaced
by a next generation of unfortunates. In a disreputable place, one might see
them on the side of the street, holding their cups and begging for coin, looking
up with white acid-scarred eyes, scarves around their necks flecked with blood,
old dried blood and fresh red blood from their constant hacking coughs. A more
humane master alchemist will provide breathing scarves to cover their apprentices
mouth and nose when they render down these substances (often smeared with the
same sort of caustic plant substances that cancel out the acidic nature of the
other ingredients, if added to the process, which can be unpleasant and lead
to chapped lips and a sore nose, but will at least mitigate the worst of the
lung scarring). The eyes must also be protected, and lenses of glass, contained
within wooden 'frames' and the whole held on the face by a set of soft leather
straps that seal tight against the face, will protect the eyes perfectly from
such damage. Ideally, the preparation chamber should be aired out between uses,
to prevent harmful side-effects for those who visit the room later.