This, however, is far from being the case; for while, in some parts, the vascular structure is preserved entire, it is also evident, that, in general, the woody structure is variously broken and dissolved by the fusion and crystallization of the flint. There are so many and such various convincing examples of this, that, to attempt to describe them, would be to exceed the bounds prescribed for this dissertation; but such specimens are in my possession, ready for the inspection of any person who may desire to study the subject. We may now proceed to consider sulphureous substances, with regard to their solubility in water, and to the part which these bodies have acted in consolidating the strata of the globe. The sulphureous substances here meant to be considered, are substances not soluble in, water, so far as we know, but fusible by heat, and inflammable or combustible by means of heat and vital air. These substances are of two kinds; the one more simple, the other more compound. The most simple kind is composed of two different substances, viz. phlogiston, with certain specific substances; from which result, on the one hand, sulphur, and, on the other, proper coal and metals. The more compound sort, again, is oily matter, produced by vegetables, and forming bituminous bodies. The _first_ of these is found naturally combined with almost all metallic substances, which are then said to be mineralised with sulphur. Now, it is well known, that this mineralising operation is performed by means of heat or fusion; and there is no person skilled in chemistry that will pretend to say, this may be done by aqueous solution. The combination of iron and sulphur, for example, may easily be performed by fusion; but, by aqueous solution, this particular combination is again resolved, and forms an acido-metallic, that is, a vitriolic substance, after the phlogiston (by means of which it is insoluble in water) has been separated from the composition, by the assistance of vital air. The variety of these sulphureo-metallic substances, in point of composition, is almost indefinite; but, unless they were all soluble in water, this could not have happened by the action of that solvent. If we shall allow any one of those bodies to have been formed by the fluidity of heat, they must all have been formed in the same manner; for there is such a chain of connection among those bodies in the mineral regions, that they must all have been composed, either, on the one hand, by aqueous solution, or, on the other, by means of heat and fusion.