Thus at _Paris_ (176), where the Water of the River _Seine_ is so full of Stony Corpuscles, that even the Pipes through which it is carried, in time are incrusted and stopt up by ’em, The Inhabitants are more Subject to the _Stone_ in the Bladder than in most other Cities. The same I observed in the _Baths_ of _Abano_, a few Miles from _Padua_, to that Degree, that it is necessary very frequently to clear the Wheel of a Mill driven by the Current of these Springs, from the great quantity of _petrify’d_ Matter with which it is from time to time incumbered. In like manner, let the gross Particles with which the _Water_ is saturated be of any other Nature, _Metallick_, _Salts_, &c. these, according to their various Gravity, the Capacity of Canals, and such like Circumstances, will, when they come to circulate in the Animal Body, be by the Laws of Motion deposited in one Part or other. So those Mineral Bodies, and Nitrous Salts, which abound in the Snowy Waters of the _Alps_, do so certainly Stuff and Inlarge the Glands of the Throat in Those who Drink ’em, that scarce any who live there are exempted from this Inconvenience (177). For this Reason, the Choice of _Water_ for Drink among the Ancients was by Weight, the lightest being preferr’d, as, most free from all Heterogeneous Bodies. The Case therefore of _Poisonous Springs_ is, their having Corrosive Corpuscles mixt with their Water, which cannot fail when forsaken in the Canals of the Body of their Vehicle, to do the same mischief as they would if taken by themselves undiluted; only with this difference, that they may in this form be carried sometimes farther into the Animal Œconomy, and so having pass’d the _Primæ Viæ_, discover their Malignity in some of the inmost Recesses. Thus the _Fons Ruber_ in _Æthiopia_, mention’d by _Pliny_ (178), about which abundance of native _Minium_ or _Cinnabar_ was found, shew’d its ill Effects chiefly on the Brain; and therefore _Ovid_ (179) says of it, ――_Si quis Faucibus hausit Aut Furit aut patitur mirum gravitate Soporem._ We shall not need then to inlarge on this Matter, since any of the foremention’d _Mineral Poisons_ may thus impart their deadly quality to Waters; and accordingly there are Instances of _Arsenical_, _Mercurial_, &c. Fountains, of which the Histories may be seen in the Collections of the Learned _Baccius_ (180). And one very remarkable in the _Philosophical Transactions_ (181). But as We before took Notice concerning _Airs_, so it may be worth the while to observe of _Waters_; that there are some Alterations of them, which tho’ not properly _Poisonous_, yet are of so great Consequence in their Effects, that they may very well deserve to be regarded.