"I consider, that as generally as Chymists are wont to appeal to Experience, and as confidently as they use to instance the several substances separated by the Fire from a Mixt Body, as a sufficient proof of their being its component Elements: Yet those differing Substances are many of them farr enough from Elementary simplicity, and may be yet look'd upon as mixt Bodies, most of them also retaining, somewhat... of the Nature of those Concretes whence they were forc'd."