I'm going to quote two somewhat dissimilar posts..please bear with me a moment:
raphfrk wrote:The process for manufacture of the saltpeter would get him some pretty weird reactions.
Basically, it is often made from urine and/or manure mixed with straw and left to ferment for a few months. The resulting decomposed mass (which contains lots of nitrates) is washed out with water. The water is passed through a filter containing the ashes left after burning wood (which converts the various nitrates into potassium nitrate). The resulting nitrate rich water is then left to evaporate, and the saltpeter is left as a residue.
Anton Gaist wrote:Thing is, researching technology is an expensive and slow process. In a world were magic is readily available, I don't see much need for someone to spend turns and schmuckers building, say, a turbine to generate electricity, when a spell can do the same. Now if magic was scarce or simply unavailable, that's be a whole other story.
I think one direction that the story could go is to have Parson introduce Industry to Erfworld. So far, the only industry we've seen is mining. (edit: Just remembered we've heard of farming, as well)
Fireworks leading to gunpowder would be an interesting test case. It's complicated enough to have fun with, and to show some similarities and differences between Earthworld and Erfworld. For instance, the only decay we've seen to date is the uncroaked. Everything else just depops. Perhaps gunpowder cannot be produced in the manner described above - I would expect that manure does not decay, and if 'unclaimed' by a dirtamancer simply depops. I would expect wood ash to depop as waste, in the same manner. On the other hand, if fireworks exist, perhaps they just pop...pay for them with shmuckers, and they pop with gunpowder inside of them. Parson would have to learn what can be harvested and what raw materials must be 'ordered.'
The purpose, of course, would be to artificially raise your side's production cap. Sure, magic is readily available, but a caster can only do so much in a given turn. If you're running at full capacity, that will happen every turn...but if you're not at war yet, what is your enormous standing army doing? Nothing.
What Parson would need to do is to figure out how to make the army's contribution multiplicative, not additive. Likely, the army's contribution will be relatively small compared to the magic contribution to whatever project he has in mind. The key will be coming up with something for the army to do that will ease the caster's burden in the next turn.
Then, the economics of the project come into play - the process of making improvised weapons for the troops must be less expensive than just ordering more expensive troops in the first place! I think that's an interesting aspect, but I doubt it'd make good reading.