In a medieval society with minor fantasy elements, a scientifically minded and not-very-ethical character is looking to acquire some strong acid for a "project" of his. He is particularly looking for acids that could burn skin and leave disfiguring scars, such as the concentrated sulfuric or nitric acid used in real-world acid attacks.
However, our "mad chemist" villain lives in a medieval period with Middle Age levels of technology, and that means he has two problems:
- Concentrating the acid into a sufficiently harmful substance. The scientific equipment to safely manufacture and concentrate acids (at least in the way a modern society would do it today) is not readily available at the current technology level. Glassware and common simple tools - such as flasks, medieval-style distillation equipment, and vials - are feasibly available in his lab, but titration equipment, digital measuring equipment and other complex modern tools are not. He could feasibly just boil an acid over a heat source, but the question is whether that would make the acid become strong enough to cause the effects he wants.
- Getting the materials. To acquire a sufficient amount of material for the concentration process, our chemist would need to find some setting-appropriate creature or animal that produces acidic or basic chemicals naturally - or locate some other natural source that would make sense to exist without being too fantastical, such as a geologically accumulated post-volcanic acid lake.
Given the details above, how would this character go about:
- acquiring a source of acid (or the materials to manufacture acid) in a way that is believable for the setting, and
- creating and concentrating a sufficient quantity and strength of acid - to the point where the acid could burn or physically scar a person - using only basic scientific tools and the equipment that would be available to him in the time period?
I am tempted to just handwave this bit of the plot as "he just finds a magical creature that has super strong acid glands and uses that to make the acid," but I want to come up with a clever way of producing it that shows the character's malicious ingenuity and scientific prowess.