The first thing to note about this book is that the title is somewhat misleading. It would be more accurate to call it a history of alchemy. I was nearly put off buying it because of its title, but in retrospect I'm glad I wasn't, because it's a very interesting book.
What the author sets out to do is to restore an understanding alchemy within its historical and cultural framework. I think he succeeds in this aim. There is in Western society a tendency to think of alchemy as being something vaguely to do with magic - but nothing could be further from the truth. The work of most alchemists would be recognized today as experimentally rigorous, and based on the best theories of the nature of matter that existed at the time.
Take, for instance, the search for the legendary Philosopher's Stone, the secret of turning lead into gold. We know that's not possible to do chemically today. Why do we know that? Because we know that lead and gold are elements. The elements are defined by the number of protons in their nucleus. Chemical reactions only work on the electrons in atoms, and you can't change the make up of an atomic nucleus by fiddling with its electrons.
But we didn't find this out until about a hundred years ago. In the golden age of alchemy, which roughly coincides with the Scientific Revolution (1500-1700), the belief was that matter was a compound, and the properties of any given piece of matter were determined by the proportions of more fundamental substances. Theoretically, if this were the case it should have been possible to change, for instance, lead into gold by altering those proportions in lead until they matched the proportions that defined gold. It was this theoretical view that drove the search for a substance that alter these proportions. (This is a simplified view the book explains in much more detail.)
The book covers the history of alchemy from it's beginnings in the third century AD through to its effective demise at the end of the 19th Century. Along the way it it discusses many other aspects of alchemy, including its impact on early medicine, laboratory work, and chemistry. It also looks in more depth at some of the work of famous alchemists, including the attempts of the author to recreate their work in the lab - with interesting results.
Well worth a read if you have any interest in the history of science.