Yeah... I'm a chemical engineer in the real world. And I work with quicklime. I absolutely have calorific stones lying around in the lab (although, usually powder). It would take me a short while to make enough to boil a bathtub of water if I had to use a lab kiln... but not a season. And I can easily make chromatic flames and vitriol (in much less than a season). Those Reagent formulae aren't semi-mythical at all. Formulae like refrigerant salt and cement as their effects are described are different, but again that's a mix just as with Theriacs where some are clearly experimental and others are clearly mundane.