I know Toady (armok be with him) has plans for extracts, but I would like to extracts with more use. This came up when I mentioned drinking troll blood and the idea struck me, should drinking troll blood give the imbiber the regenerative abilities of a troll? Not forever, or even for very long, just long enough that a single unit of troll blood could, properly prepared (to give dwarves something to do) grant the drinker a 10 or 20 frame regenerative power, healing damage across the body by a fair amount, continued consumption of extracts might cause ever lengthening durations, until the extract has gained a permanent foothold in the dwarf, similar to a disease (and in some cases, actually a disease).
Below lies a bit of a tightening of the idea.
Rawify it
. Give extract tags for common possible effects and have duration tags, potency tags (does it take 1 or 5 doses to actually take it's first effect?) that sort of thing.
Each creature would have an "alchemical use" possibly this could be done by extracts, or maybe the nature of the thing itself, so creatures might have a tag indicating the requirements for taking the "alchemical parts". Trolls, for example, might have [ALC: BLOOD] indicating that any further alchemical tags are to be associated with the blood. Eating a kosher troll would do nothing, no blood.
Gargoyles: [ALC:MEAT] [ALC_DUR:100][ALC_POT:1][ALC_EFF:ARMOUR_10][FORM:DRINK]
In the gargoyle example ALC stands for Alchemy, DUR is duration, POT is potency, EFF is effect, FORM:DRINK is fairly self explanatory and ARMOUR_(insert number here)] essentially means that the imbiber receives 10 points of armour all over. To sum it all up, eating the flesh of a gargoyle grants 10 points of "global" (all over) armour for 100 frames.
Alchemical skill on the part of your dwarves might increase the duration or effect of the new alchemical substance, so alchemy might actually be useful...
Tags for FORM: would include the basics, like food, drink, smearing (for weapons, yay) or thrown, stuff like that.
Ok, rip it to shreds.