Is it a paradox to say that a book titled The Secrets of Alchemy is open and brisk? Treatments of alchemy to this point have been either rationalist dismissals of the practice and all it represented, or dense historical works that get as lost in the details as the alchemists themselves did. In this book, Lawrence M. Principe lays out a targeted and clear (at least, as much as is possible!) history of the subject. He actually tried to carry out the described experiments, and when he encountered frustration, he persevered (sounds like normal lab work) and eventually it worked like they said in many cases. Not Philsopher's Stone cases ... but he did make a "Philsopher's Tree", which is quite wondrous in itself. If you want to really know about alchemy and what it was, read this book. I can't recommend it highly enough for answering that question.
Because the alchemists were always not quite trusted, and because they did much work in the sixteenth through eighteenth centuries as the Enlightenment was emerging and drawing its lines, they have been caught on the wrong side of those lines for a long time. Some deservedly so, but Principe's experiments show that there was some surprisingly sophisticated experimental chemistry going on.
Principe bridges the gap between modern and premodern worlds expertly, and in doing so says some things that align with Owen Barfield about how people literally see differently now than they used to. My favorite part about how premodern or early modern eyes can benefit the scientist comes from this passage about the chymist Paracelsus -- imagine this, the chemist as a co-redeemer, a high calling indeed:
p.128 -129“Paracelsus endeavored to generate an entire world system, embracing the whole of theology and natural philosophy … For him, chymical processes provided the fundamental model for explaining natural processes in the physical universe as well as within the human body. For example, the cycle of rain through sea, air, and land was for Paracelsus the great cosmic distillation. [Long list] were for him inherently chymical processes. God Himself is the Master Chymist; his creation of an ordered world out of primordial chaos was akin to the chymist’s extraction, purification, and elaboration of common materials into chymical products, and His final judgment of the world by fire like the chymist using fire to purge impurities from precious metals. Paracelsus’s system has been called a ‘chemical worldview’ … “"Some Paracelsians even held that all poison and toxicity entered the world only with original sin. Therefore, by using chymistry to purify now-poisonous substances into medicines, the chymist returned them to their wholesome, pristine, prelapsarian state as they were created by God in the beginning. In effect, the chymical process was thus redemptive, and the chymist participated as a co-redeemer of a fallen world.”