We have a striking example of the operation of time and the influences of the atmosphere, in wasting the surface of the rocks, and forming soil upon the earth; this is the kaolin of the Chinese, or the true porcelain earth, which is the produce of granite countries. The feldspar of the granite rock exposed to the atmosphere is corroded very slowly indeed, by the effects of air and moisture, and in having the soluble earth or calcareous part of its composition dissolved; the surface of this stone, thus, in a long course of time, becomes opaque in having the white siliceous earth exposed to view, and thus appears like a calcined substance. The snows and rain detaches from this surface of the rock the white earth, which being deposited in the plain below, forms a stratum of kaolin more or less pure, according to the circumstance of the place. As this operation of the atmosphere upon the surface of granite is so extremely slow as to be altogether unmeasurable to man; and as there are in many places of the earth inexhaustible quantities of this kaolin, notwithstanding a small portion only of the ablution of the rock had been retained upon the surface and deposited by itself, it must appear that much time had been required for amassing those beds of kaolin, and that these operations, which in the age of a continent is nothing, or only as a day, are, with regard to the experience of man, unmeasurable. For approbation of this theory, it is not necessary to show, that wherever there is granite found, there should be also kaolin observed; but it is necessary that wherever kaolin is found, there should be also granite or feldspar to explain its origin; and to this proof the theory is most willingly submitted. The following are the places which have come to my knowledge. First Loch Dune in the shire of Ayr; this lake receives its water from the granite hills which are at its head. Secondly, some small lakes which receive the washings of the granite mountain, Crifle, in East Galloway. Thirdly, Cornwall, a county in which I have not been, but which is sufficiently known as possessing kaolin and granite. Another example from a very distant country we have both from M. Pallas, in the Oural mountains, and from M. Patrin, who has given a mineralogical _notice_ of the Douari, _Journal de physique, Mars_ 1791. Here we find the following observation. «Parmi les chose intéressantes qu'offrent les rives de Chilea, on remarque au dessous de la fonderie, des collines de petunt-fé blanc comme la neige, parsemé de mica argentin de la plus grande ténuité. Dans le voisinage de ce petunt-fé est une argile micacée, qui en est peut-être une décomposition: on essaya en ma présence d'en faire de la poterie qui avoit tous les caractères du meilleurs biscuit de porcelaine.»