I’ve just been reading an article on alchemy which suggests that the Arab alchemists’ development of mineral acids — that is, acids stronger than the vinegar derivatives which were their predecessors — was far more valuable to civilization than if they had succeeded in transmuting base metals to gold.
It made me imagine an alternate world where alchemists did indeed learn the secret of transmutation, and metals are thus completely fungible, but where the strongest acids possible are highly concentrated solutions of acetic acid.
On the one hand, many technological applications would be eased — there would never be shortages of metals — and if transmutation could be applied to finished objects one could fabricate in a soft metal and then transmute to a hard one. On the other, chemical fertilizers and explosives would be impossible. No batteries, and some plastic would be impossible. Come to think of it, certain metals — aluminum, for example — might be unavailable; sure, they could be achieved through transmutation, but if the alchemists don’t know that a metal exists, they may never figure out how to make it.
It seems like an interesting way to kick alternate-historical industry in the rear right up to the beginning of the industrial age, at which point you’re screwed.