principle of Fresnel on the composition of two systems of undulations of the same length, which differ in position by any quantity. 3. On the direction of all the rays in the focus of mirrors, and simple or achromatic lenses. 4. The calculation of the fringes produced in the focus of a cylindric glass by the image of a luminous line. The integral which gives here the intensity of the light in each point of the focus is constructed geometrically, and verified by experiment. 15. Theory of Equations.-M. Abel, one of the most promising mathematicians of the rising generation, having investigated, has found the conditions necessary for an equation to admit of an algebraic solution; from which it results, that every equation beyond the fourth degree cannot be solved algebraically. Analysts have suspected this truth, but were not agreed respecting it. In the opinion of M. Legendre the question is now set at rest definitively. 16. A tanner, named Rapedius, of Bern Castel, on the Moselle, has discovered a new species of tan proper for dressing leather. It is the plant known by the name of Bilberry or Whortleberry (Vaccinium Myrtilus or Myrtillis), which should be gathered in spring, because at this season it dries more readily, and is more easily ground. Three pounds and a half of this tan suffice for dressing a pound of leather, while six pounds are required from the oak to produce the same effect. By this new process, tanners can gain four months out of the time required for preparing strong leather. A commission having been appointed at Treves to examine the leather so prepared, reported, that they had never seen any as good, and that every pair of shoes made therefrom lasts two months more than what are manufactured from common leather; that the skin of the neck, which it is difficult to work, becomes strong and elastic like that of the other parts. The shrub should not be pulled up, but cut with a bill, to obtain the reproduction of the plant the following year. When cut, damp does not deteriorate it, which is not the case with oak-bark, which loses ten per cent. of its value by being wetted.-Bulletin des Sci. Tech. Jan. 1829. 17. M. J. C. Leuchs has found in animal charcoal a method of preserving the must of grapes. With one pint of the juice 100 grains of animal charcoal, and more if the former contain much fermentable matter, are to be mixed. When it has lost its colour, and is clear, the charcoal is separated from it, and it is preserved in bottles and casks closely stopped. It does not ferment even in open vessels, because the charcoal has absorbed the principle of fermentation; this, however, has not become inactive from its combination with the first for if the charcoal be left in the must, this begins to ferment, but not throughout, like ordinary must in which the principle of fermentation is diffused, but only at the bottom of the vessel where the animal charcoal containing it is precipitated. -Bull. des Sciences Agricoles, Jan. 1829. 18. Græco-Egyptian Papyri.-Signor Giovanni Pelvettini, of Corfu, having translated a Greek papyrus brought from Egypt, though from what precise part is unknown, found it to be a supplication addressed to Serapis and the gods who sit with him, by Artemisia, daughter of Damasis, who intreats them to render efficacious the imprecations she utters against her father. 19. Roman Antiquities-At Sainte-Colombes-Vienne, department of the Rhone, some very perfect remains of Roman baths have been discovered, together with the mutilated remains of what must have been fine marble statues. 20. Archæology.-The Imperial Academy of Sciences at Petersburg has resolved to have undertaken at its expense a journey for the purpose of antiquarian researches throughout Russia. This interesting enterprise is intrusted to the honorary counsellor of state, M. Stroef. 21. A fine marble monument, consisting of a rectangular pedes. tal in grey marble, with a Latin inscription, has been discovered at Bordeaux. It belonged to a votive monument erected to Tutela, a mysterious goddess of the ancient city. The inscription, which is well preserved, is useful to prove the second consulship of Julianus in 224, which, although mentioned in the Capitoline marbles, has been doubted by some antiquarians. The face opposite to the inscription is decorated with a crown of oak. II. CHEMICAL SCIENCE. 1. Crystallization of Ice.-During the winter of 1821-2, Dr. Hessell observed at Lahn, near Marbourg, perfectly-formed crystals of ice, which were regular six-sided prisms, short, but with wellformed planes. This occurrence confirmed his opinion, that the crystals of ice belonged to the hexagonal or rhomboidal system; but as they did not present any planes on the borders or angles of the base, the dimensions of the prism still remain undetermined. Several of these hexagonal tables, placed one upon another, presented a grouping analogous to that assumed by the tabular calcareous spar from the Hartz. M. Hessel also had the opportunity of remarking the crystallization of ice on his window, in 1826. The layer of ice was a quarter of an inch thick: it covered the lead as well as the glass, and instead of presenting the usual vegetative appearance, it was composed of a multitude of crystals, more or less perfect; many thousands of which exhibited the form of a hexaedral prism without any modifying faces. The axis of these crystals were perpendicular to the glass on which they were fixed. In some parts they were so grouped as to assume the hopper-like form so frequently taken by, common salt.-Kastner's Archives, Bull. Univ. B. xv. 76. 2. On the Evaporation of Ice, by M. Schuebler.-The resultsobtained in numerous experiments being tabulated, gave the following general conclusions, The first column contains, the periods during which the evaporation was observed; the second, the evaporation in twenty-four hours, estimated by the height in lines from a square foot of surface, either of ice or water; the third, the mean temperature for the period during which each experiment continued; the fourth, the mean of the hygrometer (the kind of instrument not mentioned); the fifth, the mean height of the barometer at 10° of Reaumur, or 55° F. From these observations it appears that the evaporation of ice is far more considerable than has been supposed; and that in certain natural circumstances, it may surpass even that of water. During the dry cold weather of January 9th, the evaporation from ice in 24 hours was twice as great as from an equal surface of water in the middle of February, during mild cloudy weather. The gradual disappearance of snow and ice is well known; and evidently, from the above experiment, may become very rapid in very dry weather.Naturwessenchaftl. Bull Univ. A. x. 301. 3. Conduction of Heat by Wood.-In some experiments on this subject made by MM. Delarive and Candolle, bars of wood were used, each 13 centimeters* long, 4 wide, and 2.7 thick; 5 holes were made in each bar, two centimeters apart, and the first, 3 centimeters from the end. Each hole proceeded half way through the thickness of the wood, was 0.7 of a centimeter in diameter, and A centimeter is 0.3937 of an inch. being filled with mercury, had the bulb of a small thermometer placed in it. One extremity of each bar was fixed in a socket of tinned iron 2.5 centimeters long, beneath which a spirit lamp with a chimney was placed, the flame being prevented from coming into contact with the wood by screens of glass. The following table shews the temperature by the centigrade scale in each hole, when the degrees of heat had become stationary; and indicate, therefore, the conducting power. Walnut, longitudinal 80.13 43.0 19.63 9.19 5.13 Fir, ditto 7.2 3.7 8.5 3.7 Poplar, ditto Walnut, transversal 13.8 4.5 2.5 From these results it appears, that the conductibility of wood is less transversely across the fibres than in their direction; an effect which will assist in explaining how it is that trees retain a temperature approaching to that of the soil. But at the same time it should be remarked, that surfaces equal in radiating power were not given to the specimens experimented with. Mem. de Geneve, iv. 70. 4. Chemical Action of Light.-The following are some effects quoted by M. Fischer, as proper to be added to those which demonstrate the chemical action of light upon inorganic matter. If a solution of ferro-prussiate of potash be precipitated by, alcohol, the precipitate collected and rapidly dissolved in water, and the solution exposed to light, the yellow colour soon passes to green, and ultimately Prussian blue is deposited. The solution at the same time becomes alkaline; and if the experiment be made in a close vessel, the odour of hydrocyanic acid may also be observed when the liquid is examined. The salt, in fact, is in part decomposed by the action. Prussian blue, sometimes with excess of oxide of iron, is formed and deposited, and a hydrocyanate of potash left in solution. The same changes take place with the ordinary solution of the ferro-prussiate, but more slowly. They do not take place without light. The same salt crystallizes in large quadrangular plates in an obscure situation; but in bright light it gradually loses the power of yielding this form, and becomes dendritical and pulverulent. The action of light upon solutions of gold and silver is very much increased by the presence of organic matters, as gum, starch, sugar, alcohol, &c. This effect, however, has been long known, and sometimes rendered available in experiments made upon the solar rays. Kastner's Archives, ix. 345. 5. Ignition of Wire by Voltaic Electricity.When the poles of a voltaic battery are connected by a short fine platina wire, the middle of the wire becomes red hot. This effect has generally been explained by supposing that the temperature of the wire would have been the same throughout, but for the cooling effect produced at the extremities by the contact of the masses of metal constituting the poles, in consequence of which the middle part acquired the highest temperature. M. Becquerel endeavoured to ascertain whether this was the true explanation, and therefore used a wire of such length, and placed in such circumstances, that the effect of cooling at the extremities should not interfere. It is said, that the result of this experiment shewed that the temperature continues to increase from each end to the middle of the wire; and that consequently the cause which creates an electric current, of which the intensity is constant in each point of the wire, acts as an accelerating force in the developement of heat.-M. Mag. vii. 94. 6. Electricity of Woollen Cloth.-M. Muret de Bore, a manufacturer of woollen cloth at Chateauroux, has observed that, when the pieces are dried out in the air, they frequently become powerfully electric, especially when exposed to sun-light. That which is most electric is the black cloth: slight friction upon it is sufficient to produce long electric sparks: white and sky-blue cloth do not become at all electrical; deep blue and deep green weakly so; the reds produced by cochineal and madder more so.-Annales de l'Industrie, ii. 319. 7. Price of Bromine.-Bromine has now become so abundant, that M. Quesneville, of Paris, is able to sell it for M. Balard, the discoverer, at the price of fifteen francs per ounce. 8. Peculiar production of Ammonia.-M. Hollunder mixed liver of sulphur and pure iron filings together, put them into a covered crucible, and exposed them to a high temperature. When the double sulphuret thus obtained was moistened with a little water, it disengaged abundant vapours of ammonia, and continued to do so, as long as it continued hot. Kastner's Archives, Bull. Univ. A. x. 312. 9. Cyanide of Sulphur.-This compound has been formed by M. Lassaigne, by putting pulverised cyanide of mercury into a small glass globe, adding half its weight of bi-chloride of sulphur, closing the vessel, and leaving it for twelve or fifteen days in common day-light. Small crystals, amounting in weight to about one twenty-fourth part of the mixture, sublimed to the top of the globe, which, being collected, mixed with a little carbonate of lime, and re-sublimed, were pure cyanide of sulphur This substance crys➡ tallizes in fine rhomboidal plates, resembling those of chlorate of 9 |