To this _Hypothesis_, is subjoin'd an Examination of the _Scholastick_ opinion of _Substantial Forms_; where the Author, _first_, States the Controversie; _next_, gives the Principal reasons, that move him to oppose that Opinion; _then_, answers the Main arguments employed to evince it; _further_, assigns both the _First_ Cause of Forms (_God_;) and the Grand _Second_ Cause thereof (_Local Motion_:) and _lastly_, proves the _Mechanical_ Production of _Forms_; grounding his proof, _partly_ upon the Manner, by which such a _Convention of Accidents_, as deserve to pass for a _Form_, may be _produced_; as that the Curious Shapes of _Salts_ (believed to be the admirablest Effects and strongest Proofs of _Substantial Forms_) may be the Results of _Texture_; _Art_ being able to produce Vitriol, as well as _Nature_: _partly_, upon the possibility of _Reproducing_ Bodies by skill, that have been deprived of their reputed _Substantial Forms_: Where he alledges the _Redintegration of Saltpetre_, successfully performed by himself; though his Attempts, made upon the dissipation and re-union of _Amber_, _Allum_, _Sea-Salt_, and _Vitriol_, proved (by reason of _accidental_ hindrances rather, than of any impossibility in the Nature of the Thing) less successful. In the _Second_ and _Historical_ Part, the Author, appealing to the Testimony of Nature, to verifie his Doctrine, sets down, _both_ some _Observations_, of what Nature does without being over-ruled by the power and skill of man; and some _Experiments_, wherein Nature is guided, and as it were, mastered by Art. The _Observations_ are four. 1. The _First_ is taken from what happens in the _Hatching of_ {194} _an Egge_; out of the _White_ whereof, which is a substance Similar, insipid, soft, diaphanous, colourless, and readily dissoluble in cold water, there is by the _New_ and _Various_ contrivement of its small parts, caused by the Incubation of the Hen, an Animal produced, some of whose parts are opacous, some red, some yellow, some white, some fluid, some consistent, some solid and frangible, others tough and flexible, some well, some ill-tasted, some with springs, some without springs, &c. 2. The _Second_ is fetcht from _Water_, which being fluid, tastless, inodorous, diaphanous, colourless, volatile, &c. may by a _Differing Texture_ of its parts, be brought to constitute Bodies, having qualities very distant from these, as _Vegetables_, that have firmeness, opacity, odors, tasts, colours, Medicinal vertues; yielding also a true _Oyle_, that refuses to mingle with _Water_, &c.