stylistic:tone
Robert Boyle

In 1661, in The Sceptical Chymist, Robert Boyle proposed his theory of corpuscularism which favoured the analysis of matter as constituted of irreducible units of matter (atoms); and, choosing to side with neither Aristotle's view of the four elements nor Paracelsus ' view of three fundamental elements, left open the question of the number of elements. Boyle argued against a pre-determined number of elements—directly against Paracelsus' three principles (sulfur, mercury, and salt), indirectly against the "Aristotelian" elements (earth, water, air, and fire), for Boyle felt that the arguments against the former were at least as valid against the latter.

Much of what I am to deliver... may be indifferently apply'd to the four Peripatetick Elements, and the three Chymical Principles... the Chymical Hypothesis seeming to be much more countenanc'd by Experience then the other, it will be expedient to insist chiefly upon the disproving of that; especially since most of the Arguments that are imploy'd against it, may, by a little variation, be made... at least as strongly against the less plausible, Aristotelian Doctrine.

Then Boyle stated his own view in four propositions. In the first and second, he suggests that matter consists of particles, but that these particles may be difficult to separate. Boyle used the concept of "corpuscles"—or "atomes", as he also called them—to explain how a limited number of elements could combine into a vast number of compounds.

Propos. I.... At the first Production of mixt Bodies, the Universal Matter whereof they... consisted, was actually divided into little Particles.... The Generation... and wasting of Bodies... and... the Chymical Resolutions of mixt Bodies, and... Operations of... Fires upon them... manifest their consisting of parts very minute... Epicurus... as you well know, supposes... all... Bodies... to be produc'd by... Atomes, moving themselves to and fro... in the... Infinite Vacuum.... Propos. II.... These minute Particles... were... associated into minute... Clusters... not easily dissipable into such Particles as compos'd them.... If we assigne to the Corpuscles, whereof each Element consists, a peculiar size and shape... such... Corpuscles may be mingled in such various Proportions, and... connected so many... wayes, that an almost incredible number of... Concretes may be compos'd of them.

Boyle explained that gold reacts with aqua regia, and mercury with nitric acid, sulfuric acid, and sulfur to produce various "compounds", and that they could be recovered from those compounds, just as would be expected of elements. Yet, Boyle did not consider gold, mercury, or lead elements, but rather—together with wine —"perfectly mixt bodies".

Quicksilver... with Aqua fortis will be brought into a... white Powder... with Sulphur it will compose a blood-red... Cinaber. And yet out of all these exotick Compounds, we may recover the very same running Mercury.... Propos. III.... From most of such mixt Bodies... there may by the Help of the Fire, be actually obtain'd a determinate number (whether Three, Four or Five, or fewer or more) of Substances... The Chymists are wont to call the Ingredients of mixt Bodies, Principles, as the Aristotelians name them Elements.... Principles... as not being compounded of any more primary Bodies: and Elements, in regard that all mix'd Bodies are compounded of them.

Even though Boyle is largely regarded as the first modern chemist, The Sceptical Chymist still contains old ideas about the elements, alien to a modern viewpoint. Sulfur, for example, is not only the familiar yellow non-metal, but also an inflammable "spirit".