Those distinct substances, which concretes generally either afford, or are made up of, may, without very much inconvenience, be called the elements o… - Robert Boyle

Since a great part of those Learned Men, especially Physicians who have discerned the defects of the vulgar Philosophy, but are not yet come to understand and relish the Corpuscularian, have slid into the Doctrine of the Chymists; and since the Spagyrists are wont to pretend to make out all the Qualities of bodies from the Predominancy of some one of their three Hypostatical Principles, I suppose it may both keep my opinion from appearing too presumptuous, and (which is far more considerable) may make way for the fairer Reception of the Mechanical Hypothesis about Qualities, if I here intimate (though but briefly and in general) some of those defects, that I have observed in Chymists Explications of Qualities.

Among Latin writers, the acceptations of the word nature are so many, that I remember, one author reckons up no less than fourteen or fifteen. Hence we see how easy 'tis for the generality of men, without excepting those who write of natural things, to impose upon others and themselves, in the use of a word so apt to be mis-employ'd. ..the very great ambiguity of this term, and the promiscuous use made of it, without sufficiently attending to its different significations, render many of the expressions wherein 'tis employ'd either unintelligible, improper, or false.

It is somewhat strange to me, that neither the Spagyrists themselves, nor yet their Adversaries, should have taken notice that Chymists have rather supposed than evinced, that the Analysis of bodies by fire, or even that at least some Analysis is the onely instrument of investigating what Ingredients mixt bodies are made up of, since in divers cases That may be discovered by Composition as well as by Resolution; as it may appear, that consists of metalline parts (whether Martial, or Venereal, or both) associated by Coagulation with ones, one may, I say, discover this as well by making true Vitriol with Spirit (improperly called Oil) of Sulphur, or that of Salt, as by distilling or Resolving Vitriol by the fire.