The acquisition of another kind of power by water under such conditions was exemplified by the conversion of pine-wood into a bright and hard black substance resembling anthracite, and consisting simply of carbon associated with small quantities of volatile substances. It was shown, by its granulation in small globules, to have passed, in the water, through a kind of fusion. The reactions from which these products resulted are all the more interesting because they were obtained with a very small quantity of water, hardly equal to a third of the weight of the metamorphosed glass. Furthermore, the new products crystallized at a temperature considerably lower than their point of fusion. It is thus proved that water highly superheated acquires an energy that was unknown to belong to it. It destroys combinations that were reputed to be stable, and in the presence of which it was regarded as inert; and it composes others, among which are the anhydrous silicates. The production of these silicates in the crust of the earth escapes our observation, because it requires a temperature greatly superior to that of boiling water. But it must be going on in the depths of the rocks, where there is no lack of imprisoned water, nor of temperatures and pressures incomparably higher than those of our most potent experiments. It is hardly necessary to say more concerning the application of these synthetic results to questions concerning the metamorphic transformation of entire regions.
Other facts in nature are explained in these experiments. First, they teach us the origin of quartz in the crust of the earth, where it appears everywhere and in the most diverse bearings. Have not the veinlets of this mineral, for example, which traverse quartzites and phyllads in every direction, probably separated themselves at the expense of the incasing rock, and in the presence of water and heat, just as the quartz was extracted from glass? An action of the same kind is recognizable in the metalliferous veins. Sometimes the temperature there is high enough for the silicates also to be generated. The veins in which the green emeralds of Peru are found associated with crystallized quartz, calcite, and pyrites are evidently of aqueous formation.
Thus, by going back to ancient periods, we have seen how numerous species of minerals are produced concerning whose origin the observation of facts occurring to-day can not inform us. These numerous minerals, whether metalliferous or stony, occurring in various formations, are the final result of the work of water, which is found in some way stereotyped in them. We have thus succeeded in discovering the intimate operations of that liquid in laboratories which it abandoned long ago, in fissures of greater or less magnitude, and in blisters or the simple pores of the rocks. We are instructed concerning the manner in
