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VII. [1]The Concretion is, in ſome of theſe Subſtances, owing to Heat; and in others to Cold. There is perhaps nothing to hinder but that the Coaleſcence of ſome Kinds of Stones may be occaſioned by the one, and of others by the other of theſe Cauſes: though that of the Earths of all Kinds ſeems owing only to Heat. From theſe contrary Cauſes, however, may happen the Concretion, or Diſſipation of contrary Subſtances.
- ↑ The Author has here, in his accuſtomed clear and ſuccinct Manner, given his Opinion in regard to the Cauſes of the Concretion of that Matter, the nature of which he had before deſcribed, for the Formation of the Bodies which are to be the Subject of the preſent Treatiſe.
The certain and immediate Cauſe of the Coheſion of theſe Particles, which had before, by their Gravity, been precipitated from among the fluid Matter in which they were at firſt ſuſpended, was that univerſal Property in Matter called Attraction. The Preſſure of the circumambient Atmoſphere may ſerve to account for the Coheſion of large Maſſes of Matter: but the minute Contacts of leſſer Particles of it, which ſometimes cohere with a Force almoſt infinitely greater than the Preſſure upon them can be ſuppoſed to influence, reduce us to a Neceſſity of having Recourſe to this other
Stalactitæ; or at the Bottom, and left in Maſſes called Stalagmitæ, or Dropſtones, is another very frequent one. Many others there alſo are; but the Bodies formed by theſe, as well as thoſe, though not brought together by mere Percolation, or mere Afflux, are however, in general, of the Number of thoſe formed of Particles originally brought together by the one or the other of theſe Means, and therefore very juſtly reducible under them as general Heads. What the Author adds of the various Stones and Earths, thus formed, owing their different Qualities to the Variety and Purity of the conſtituent Matter, and of the Manner of their Concretion, is plain, evident, and inconteſtable.
