The unstratified, and more crystallized substances, were cast in the bosom of others, which were solid at the time when they were fluid. In all this, therefore, there is no indication of a fluidity prevailing through the whole mass, or even over the whole surface of the earth, and therefore nothing that can explain the spheroidal figure which it has acquired. The supposition, then, of the entire body of the earth, or even of its external crust, having been fluid, though it might account for the compression at the poles, does not connect that fact with the other facts in the natural history of the globe, and fails, therefore, in the point most essential to a theory. It is liable, also, to other objections, whether it be conceived to have proceeded from fire or from water; whether it has happened on the principles of Buffon or of Werner. 431. First, let us suppose that the fluidity of the earth, or of the external crust of it, at least to a certain depth, proceeded from a solution of the whole in the waters of the ocean; and, waving all the objections that have been stated to this hypothesis, on account of the absolute insolubility of many mineral substances in water, let us suppose them all soluble in a certain degree, and let us compute the quantity of the menstruum, which, on the suppositions most favourable to the system, must have been required to this great geologico-chemical operation. The siliceous earth, though not soluble in water _per se_, yet, after being dissolved in that fluid by means of an alkali, was found by Dr Black, in his analysis of the Geyser water, to remain suspended in a quantity of water, between 500 and 1000 times its own weight. This is one of the facts most favourable to the Neptunian theory; and that every advantage may be given to that theory, we shall take the least of the numbers just mentioned, and suppose that siliceous earth may be dissolved or suspended in 500 times its weight of water. Taking this for the extreme degree of insolubility of mineral substances, (though there are many of which the insolubility is absolute, or, to speak in the language of calculation, infinitely great,) we may suppose the insolubility of all the rest, or the quantities of water in which they are dissolved, to be ranged in a descending scale from 500 to 0, the extreme degree of deliquescence. Then, taking the arithmetical mean between these extremes, it will give us 250, as the proportion of water in which mineral substances may at an average be dissolved. But this average is much less than the truth; for the quantity of siliceous earth is great in comparison of any of the rest, and the mineral substances that are extremely soluble in water are but in a small quantity; therefore, when we suppose mineral bodies, at a medium, to be soluble in 250 times their own weight of water, we make a supposition extremely favourable to the Neptunian system.