stone, composed chiefly of flints, quartzose sandstone, plastic clay, marls, &c. In these are distributed, in nodules, beds and druses, quartz, agates, sulphate of strontian, calcareous spar, selenite, sulphuret and hydro-oxide of iron, sulphuret of zinc, amber, mellite, and petroleum. The fossil remains of vegetables are in number twenty six, many of which are well defined, part being in the state of lignite, part siliceous, and a few in the state of coal. From the list of plants found in the lignite some remarkable facts are evident, which were unknown till within twenty years. It is ascertained that many of the plants belong to families which do not now exist near where the lignites are found; nor are the remains of aquatic plants more abundant than those of any other families. No marine plants have been observed, and there is no reason why they should not have been preserved as well as any others; no ferns, or leaves, or stems of plants of this family have been met with, although they are so common in beds of coal. M. Adolphe Brongniart, in his memoir on the fossil vegetables, asks if this is not attributable to the nature of the buried plants, rather than to the absence of fuci from the surface of the earth, when the lignite formation was deposited. Plants according to him could not have been buried where they are now found, but from two circumstances. Either they grew upon the soil itself, which covered them as fast as the grew; or they have been covered by earthy or stony depositions of a different nature, spread upon the soil by the operation of causes of which we are ignorant. This appears to have been the case with the algo, in the marine. deposites, the ferns in peat bogs and coal-fields, which were neither marine nor fresh-water deposites; this is the case with the canes. nymphoæ, &c. in the deposits from lakes and rivers; now the lignite formations belong to the latter, and the ferns were not aquatic plants, they could thrive at the surface of the earth, while the lignite formation was depositing, without, however, being found in the formation. Or the buried plants did not grow in the formation, in which they are now found in a fossil state; and in this case they appear as if they had been brought from a distance by the wind and currents of water, which left them where they are now found; either in the sea, in which case they were mixed with marine plants, or in lakes and ponds, and here they were mixed with the products of lakes. But had they been dragged along in this manner, they must have been destroyed, or have been torn easily from the soil, or from their stalks, the fuci could not have been affected by these causes from their firm attachment to the soil. According to this hypothesis, the trunks of trees which we find in the lignite formation, ought to have belonged either to trees that grew in watery places, or they are trunks and branches which could have been washed there by the waters. These observations give an idea, of the very different circumstances under which the coal formation and the lignite formation were formed, both composed of an immense accumulation of vegetable matter; this is in accordance with the geological facts. The mass of the first formation is composed of plants that flourished on the dry land, and which are buried in the place where they grew; that of the second is composed of aquatic plants also buried in their native spot. In the first, there are hardly any foreign vegetables. In the second, on the contrary, the mass of foreign vegetables is often more considerable than that of the indigenous plants. There have not, as yet, been found, any vegetables adhering strongly to fresh-water soils, nor leaves attached to the stems; that is to say no aquatic plants, for the reason given above; they may, however, be met with, but the observaproves that it is a very rare occurrence. These considerations, presented for the first time in the memoir just cited, are of great importance in a geological theory, indicating, if they do not show distinctly, the organic differences between the formations of coal and those of lignite. tion The manner in which the vegetable debris presents itself in these deposits of lignite, will contribute to acquaint us with the circumstances under which these deposits were made. The plants are not found in one constant direction, as has been before supposed, but they are in all directions. They are not always in a horizontal position, and we meet with many trunks of trees in a vertical position, in coal-fields. M. Noggerath, who is occupied with this question, noticed at Pützburg, a tree in a vertical position, which is more than three metres in diameter, and on which he counted seven hundred and ninety two concentric rings. M. Brongniart next proceeds to speak of the remains of animals, which are found with the lignites. Among these we find some of the largest of the mammiferes, the remains of crocodiles, and an abundance of fossil shells. Hence, it is inferred, that the lignite soissonnois was deposited from fresh water. The lower part of the deposite at Epernay presents in a striking manner, an abundance of fresh-water fossils, while the upper portion contains a mixture of the same, with those of marine animals. As regards the formation of which lignite is à subordinate member, it is first met with in the oldest coal formation with remains of ferns, to this would belong the lignite of South Hadley, in Massachusetts. The greatest depth at which it has been found, is in the calcareous marl below the oolite, and above the alpine limestone, the lias of the English geologists, the muschelkalk of the Germans. A very remarkable fact in the geological history of the lignites, is their occurrence in the rock salt of Wieliczka. It is sometimes in the state of jet, sometimes fibrous and bituminous; in the last case it gives out a strong odour analogous to that of truffles, or certain decaying marine animals. The sandy deposites which cover this salt formation, contain also lignite with mellite. These circumstances furnished M. Beudant with one of the arguments which led him to refer the saline formation, at the foot of the Carpathian mountains to the tertiary. The lignite which occurs above the lignite soissonnois, is described as a distinct diluvian deposit; and M. Brongniart has attempted to establish four formations of this substance; viz. 1. Lignite of the lias. 2. Lignite of the island of Aix. 3. Lignite of Soissons. 4. Upper lignite. The analogy between the minerals and rocks of these, and those of the coal formations, notwithstanding the difference in age and position of the formations, is remarkable. The memoir closes with a description of the localities of lignite at considerable length, among which the author notices the well known localities of Gay-Head, Martha's Vineyard, and South-Hadley, in this state. ART. XIV.-Chemical Analysis of the Sea-Water of Boston Harbor. By J. W. WEBSTER, M. D. A QUANTITY of the water from this harbor was taken up after a continuance of dry weather, and at such a distance from the land, that no error was to be apprehended from an unusual admixture of fresh-water; circumstances which have perhaps not been always sufficiently attended to in the analysis of saline waters. After a number of preliminary experiments, in which the presence of no other substances than what are usually met with, in waters of this class, was detected, the method of analysis recommended by the late Dr Murray, was resorted to. 1. One pint of the water was slowly evaporated to a sufficient degree, and a saturated solution of muriate of barytes was added as long as any precipitation took place; care being taken to avoid any excess. The precipitate was collected and dried at a moderate red heat; it weighed 47.5 grains, and was sulphate of barytes, indicating 16.1 sulphuric acid. By a preliminary experiment, it was ascertained that this precipitate did not effervesce with muriatic acid. 2. A solution of oxalate of ammonia was added to the clear liquor, as long as any appearance of precipitation took place. The precipitate was washed, dried, and converted into a sulphate by sulphuric acid; it was then exposed to a red heat, and weighed six grains, indicating 2.4 of lime. 3. The clear liquor was heated, and solutions of carbonate of ammonia, and phosphoric acid, were added, the former in excess, as long as any precipitation was produced. This precipitate, washed and dried, was converted into phosphate of magnesia by exposure to a red heat during one hour; it weighed thirty-four grains, equivalent to 13.6 of magnesia. 4. The remaining liquor was evaporated to dryness, and the dry mass, after exposue to heat until no more vapours escaped from it, was finally heated to redness. The result was 96.8 for the real quantity of muriatic acid. General Entelligence. Elements of the Comet of 1823, '24.-In our last we gave the elements of this comet, as computed by Mr Colburn. The following is from the Philosophical Magazine for April. 1. The first are by Mr J. Taylor of the Royal Observatory, Greenwich. 2. The second are by Professor Nicolai Schumacher, Astr. N. N. 48. B. 3: giving the greatest error in A. R. + 18", in decl. + 11". 3. The third by Mr Hansen, A. M. 48. B. 3. 4. The fourth by Carline. 5. The fifth by Dr Brinkley. 6. The sixth by Mr Richardson of Greenwich. 1. 1823, Dec. 9.3697 D. Greenwich Semi-decussation of the Optic Nerves.-At a late meeting of the Royal Society, a paper was read, "On the Semi-decussation of the Optic Nerves, by W. H. Wollaston, M. D. V. P. R. S." It has been generally concluded by anatomists, and they support the conclusion from the observation of the arrangement of the optic nerves, as distinctly seen in certain kinds of fishes, that in the human eye, the optic nerves, after passing from the thalami nervorum opticorum, meet, and then proceed apparently in union, though in reality still separate; so that the right eye is believed to be entirely supplied with these nerves from the left thalamus, and the left eye from the right thalamus; and this arrangement is called the decussation |