PREFACE.

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A S all the arts, by which matter is diverfiy modifiedand accommodated to human uses, have a necessarydependence upon the properties or qualities of thebodies on which they are exercised; enquiries into the pro-perties of different bodies, and the effects resulting fromvarious applications of them to one another, become ap-parently of primary importance, as well for the illustrationand improvement of the present arts and the discovery ofnew ones, as for the advancement of useful knowledge.

The properties of bodies make the object of two sciences,natural philosophy and chemistry ; which, though in manycafes so closely interwoven, and so nearly allied, that per-haps no boundaries can be established between them, ap-pear in others to have essential and important differences.In the introduction to a work, of which enquiries into theproperties and relations of bodies make a principal part,the necessary precision, in regard to matters of fact, as wellas of science, requires that we should endeavour to distin-guish them.

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Natur-aæ.