But it was destined for the writers of our days to explain and support, by numerous examples, the advantage of proper rotations. M. Yvart, one of those who has paid most attention to the subject, has the merit of drawing all his from the soil of France itself. His instances are very numerous. He has given them for all climates, for all exposures, for all varieties of soil. He has shown that we may every where suppress the fallows, and introduce in their place a rotation of crops much more productive, and capable of retaining all the fertility of the soil. M. Hassenfratz, divisionary inspector of mines, charged by government to publish a treatise on metallurgy, has submitted to the Class the first part of it, entirely devoted to the extraction of iron from its ores, on account of the importance of this metal for the arts, and the numerous works required by the different modifications of which it is susceptible. It has been found that the facts contained in this work are arranged in a natural order; that all the processes are explained with clearness; and that it may be considered as a general collection of every thing known respecting iron, either from books, from workmen, or ironmasters. This first part has been recently published. ARTICLE XIV. SCIENTIFIC INTELLIGENCE; AND NOTICES OF SUBJECTS I. Ulmin. Notwithstanding the various observations and experiments which I have had an opportunity of making on ulmin, it is only lately that I have been so fortunate as to meet with it in a state of purity, so as to be able to ascertain its real properties, and to assign it a true place among vegetable substances. I received some time ago from Dr. Leach a specimen of a black matter which he had collected on an oak in the neighbourhood of Plymouth. It turned out, on examination, to be ulmin quite free from potash, a substance which had constituted a part of all the specimens formerly examined either by Mr. Smithson or myself. It was in small lumps, mostly attached to each other by vegetable fibres. Its colour was a very dark brown, almost black It had little or no taste. It was considerably firmer than the ulmin mixed with potash, and of a greater specific gravity. I found its properties as follows: 1. Nearly tasteless. 2. Dissolves very slowly, and in small quantity, both in water and alcohol. The solution is pale brown, and tasteless. 3. The aqueous solution is not precipitated by sulphate of iron, sulphate of copper, sulphate of zinc, or nitrate of silver. 4. Nitrate of mercury, and superacetate of lead, occasion brown flocky precipitates; but both of these salts were precipitated white by distilled water. 5. The acids occasion no precipitation in the aqueous solution. 6. The alcohol solution was precipitated dark brown by sulphate of iron and sulphate of copper. 7. When a weak solution of carbonate of potash is poured upon this ulmin, a dark brown solution is immediately effected, which possesses all the properties formerly described in my paper on ulmin, in the first Number of the Annals of Philosophy. I burned five grains of this ulmin in a platinum crucible. A white ash remained, weighing 0.27 grain. It contained no perceptible portion of alkali, but dissolved with effervescence in nitric acid, and was wholly carbonate of lime. The most striking property of ulmin is its affinity for carbonate of potash. It is by means of carbonate of potash that it is usually so soluble in water. The acids throw it down, merely by depriving it of its potash. The metalline salts throw it down from its alkaline solution by a double decomposition. II. Ulmin from the Horse-Chesnut. Mr. Sowerby was so obliging as to send me a specimen of a black matter which he collected from a horse-chesnut (Esculus hippocampus) growing in a garden in Southgate. In appearance and taste it resembled former specimens of ulmin very closely; but it was so much mixed with portions of the bark of the tree, that I could hardly obtain any quantity in a state of perfect purity. Ten grains of it (not free from bark) being burnt in a platinum crucible, left 144 grain of a white ash. This consisted chiefly of carbonate of potash mixed with a little carbonate of lime, and with a portion of silica, which I could not weigh, but estimated at about 0 04 grain. It was dissolved in nitric acid, and shot into small crystals of saltpetre. It appears, then, that this ulmin contains less potash than the ulmin from the elm. Five grains of it being treated with water, formed a dark brown solution, and left behind a portion of black looking matter, which I found to be bark. This solution was not precipitated by acids, nor by sulphate of zinc, nor muriate of tin. Sulphate of iron threw down a grey precipitate; sulphate of copper, a green; nitrate of silver, a white; and acetate of lead, a yellow, These differences from the ulmin of the elm seem to depend upon the smaller quantity of potash present, which prevents water from dissolving so great a quantity as to be precipitated by acids. III. Fall of Stones from the Almosphere, near Chester. 15th of September, containing the following information, which the writer says was first communicated to the public in a provincial newspaper. He does not give the date; but merely quotes the following passage from the newspaper, in the words of the anonymous writer of that article. "Last week, having occasion to go to Malpas (a village 15 miles from Chester), I witnessed a very singular phenomenon. About one o'clock in the day, from the great heat and the calmness of the air, I apprehended a thunder-storm, and supposed my apprehensions were going to be realised, when I beheld a bright cloud, out of which fell some large stones, which were soft and intensely hot at first, but afterwards acquired considerable hardness." I am not aware that any of the stones in question have been brought to London. These phenomena have been of rare occurrence in Great Britain of late; but five or six examples of similar falls on the Continent, during the years 1811 and 1812, have been recorded, and the stones subjected to chemical analysis, As some of the results of analysis are curious, I have been intending to lay them before the readers of the Annals of Philosophy, but have hitherto been prevented by want of room. IV. Swedish Agriculture. I take this opportunity of correcting a very important mistake which occurs in my Travels in Sweden, relative to the quantity of grain produced annually in the kingdom. In page 426 of that work I have given an official table exhibiting the quantity of ground in tillage, and the annual produce in spanns; and I say, below the table, that the Swedish spann contains 28 kanns, or 44 English wine pints. This statement I took from a Swedish dictionary, published at Stockholm in 1807. But I have received a letter from a Swedish gentleman in London, stating the following to be the real amount of the Swedish measures, from his own personal knowledge, which I have no reason to call in question. 1. The Swedish tunn consists of two spanns heaped as much as can be laid on the top, and is the only lawful measure of the country. It amounts to French cubic English cubic inches. .9438.8 .... 149.9 Now a Winchester bushel is 2150-42 cubic inches: therefore the Swedish tunn, according to the preceding statement, is 4.3893 Winchester bushels, and the Swedish spann is 2.19465 Winchester bushels; so that these measures are above 40 fold greater than I made them. This removes the extraordinary barrenness, which appeared so very striking according to my original estimate; so that the tunnland (1+ acre) produces I annually rather more than eight Winchester bushels of corn. thought it right to make this error known as soon as possible, to prevent any erroneous inferences from being drawn from the table in question. V. Sulphate of Soda. Want of room obliges me to defer for the present the continuation of the table of the constitution of the salts: but I think it necessary to point out a mistake in that part of the table which was inserted in the last Number of the Annals of Philosophy. Sulphate of soda (p. 294) is said to be composed of I integrant particle of sulphuric acid + 2 integrant particles of soda. From the note it will easily be seen that the reverse is the case. It is composed of 2 s. a. + 1 soda, and its weight, of upon it in page course, is 10-7882. Hence the remarks made 300, as an exception to Berzelius's rule, are erroneous. not yet met with any exception to his rule, except among the nitrates. These exceptions he admits, and endeavours to obviate by the ingenious theory published in this and the preceding Number of the Annals of Philosophy. VI. Electrical Oxides. I have The beautiful figures produced on paper by the oxidation of various metals with an electrical battery, cannot be effectually represented by engravings. Mr. Singer proposes to illustrate a few copies of his Elements of Electricity (now in the Press) with some real oxides, produced by his powerful apparatus. Those who desire such copies may secure them by an early transmission of their names to Mr. Singer. VII. Practical Chemistry. Dr. Thomson proposes next winter to give a Practical Course of Chemistry to a very limited number of young Gentlemen, who will reside in his house during its continuance. The Course will begin on the 1st of January, 1814. ARTICLE XV. Scientific Books in hand, or in the Press. Mr. Kerrison is preparing for the Press An Inquiry into the Establishment and Progress of the Medical Profession in England, as it regards the Physician, Surgeon, Apothecary, General Practitioner, and Chemist and Druggist; with a Compendious Analysis of all the Charters granted to Physicians, Surgeons, and Apothecaries, tending to illustrate the Merits of the Bill about to be submitted to Parliament by the Associated Surgeon-Apothecaries of England and Wales. Mr. W. Henley is about to publish a Series of Chemical Tables, intended to exhibit the Properties of all the present known Bodies, the Result of their Union, &c.; forming a Complete Abstract of the Science of Chemistry. ARTICLE XVI. METEOROLOGICAL JOURNAL. 1813. Wind. Max. | Min. Med. Max. Min. Med. Evap. Rain. E30.22 30 1130.165 72 56 64.0 58.0 43 57.5 20N E 29.90 29.89 29.895| 66 45 55.5 70 50 48 58.0 The observations in each line of the table apply to a period of twenty-four hours, beginning at 9 A. M. on the day indicated in the first column. A dash denotes, that the result is included in the next following observation, O |