Nay, so abundant in some quarters of the globe has vegetable matter been at this period, that there are traces of beds, approximating to coal, entirely composed of it, and the rocks inclosing these beds so charged with bitumen and carbon as to be used as fuel. “The silurian strata of the Scandinavian peninsula and the Island of Bornholm, contain,” says Professor Forchhammer, “in their oldest parts, large beds of aluminous slate, which is used in a great number of manufactories for making alum; and this aluminous slate has the great advantage over those slates of the carboniferous system of Germany and a part of France, that it contains the sufficient quantity of potash which is required to make alum.” It is well known that potash constitutes an ingredient in most vegetable bodies; and that when a plant is burned there remains a skeleton of this substance. Hence, possibly, the origin of the potash in the alum slate. But the argument does not rest upon inference. The same authority relates, that in Bornholm and in Scania, the southernmost part of Sweden, this slate contains a great number of impressions of a fucoidal plant, of which Liebmann has given minute botanical descriptions. Then, pursuing his interesting tale of this first flora of creation, he says,—“According to Professor Keilhau, Professor Bock, and M. Esmark, the same ceramites occurs frequently in the aluminous silurian slate of Southern Norway. Recently M. Hisinger has figured an imperfect specimen of it from Berg, in the province of Ostergothland, in Sweden. Thus this fucus appears to be characteristic of the alum slate of Scandinavia: and I can scarcely doubt that the most characteristic properties of the alum slate, as depending upon its carbon, its sulphur, and its potash, are derived from the great quantity of sea-weed which has been mixed up with the clay, and whose carbonaceous matter so affects the whole rock, that the slate is used as fuel for boiling the aluminous liquor, and burning lime; and in some parts of the province of Westergothland in Sweden, even small courses of true coal occur. There can hardly remain any doubt that this coal is derived from sea-weeds, of which fossil parts have been found, for not the slightest trace of land plants has ever been discovered.”