Ashmole was interested in Alchemy but this does not automatically means that ancient Masonry practiced Alchemy. However I think that Alchemy was one of their interests but for reasons that are too long to explain. The problem is that nowadays Alchemy is considered simply from its esoteric aspects. However Alchemy was not only chemistry but was a general name that covered al lot of different disciplines, some esoteric and some not like medicine and metallurgy. Already much before the modern scientific method there were scholars who considered those who looked for stuffs like the "gold fabrication" or the "creation of philosopher's stone" as crazy guys, while the methods to improve steel quality were regarded as serious, even if theye were really fanciful. The absence of a scientific method was a big limit, but in this regards Alchemy was not different from Architecture where many concepts and design method had not a scientific base and caused a lot of failures and collapses, also of buidings that we regards nowadays as masterpieces.