MAGNETISM.

5. Effect of Magnetism on the Balance of Chronometers.— It appears from a curious paper by Mr Fisher, on the Errors in Longitude, as determined by chronometers at sea, that a sudden alteration takes place in the rates of chronometers, when taken on board of ships, an effect which has been generally ascribed to the motion of the vessels. He ascribes the acceleration which takes place to the "magnetic action exerted by the iron in the ship, on the inner rim of the balance, which is made of steel;" and in proof of this, he found, that analogous effects took place in chronometers when under the influence of magnets placed in different positions with respect to their balances. "Upon the whole, says Mr Fisher, it appears that chronometers will be generally accelerated (particularly if their balances have not received polarity by the too near approach of any thing magnetical) on ship-board. It appears probable, likewise, that the force of the balance-springs is affected in the same way, since it is well known that chronometers having gold balance-springs, although more difficult to adjust, yet keep better rates at sea than others."-Phil. Trans. 1820, p. 207.

6. Diurnal Variation of the Needle, &c.-The following interesting results are given by M. Hansteen of Christiania. 1. The magnetic intensity of the earth is subject to a diurnal variation, decreasing from day-break till 10h or 11h A. M., when it reaches its minimum, and from thence it increases till 4h or 5h P. M. It then decreases, and afterwards appears to reach a maximum about 3h A. M. 2. Two or three days after the moon crosses the equator, the magnetic intensity seems to be weakened. The same happens during an aurora borealis. 3. The magnetic intensity is also subject to an annual variation, being greater in the winter than it is during the summer. 4. Every object, of whatever materials it consists, when suspended in a vertical position, has a magnetic north pole at its lower end, and a south pole at its upper end.

ELECTRICITY.

7. Experiment in favour of one Fluid.-M. Van Marum, in » Memoir, lately read at the Royal Institution of the Sciences of

Amsterdam, has given various interesting historical details respecting the adoption of the theory of two fluids by the French mathematicians. He considers that the discovery which he made in 1784, with the great Teylerian machine, of the ramified form of the spark, which passed from the first conductor to the receiving conductor opposite, affords an experimentum crucis in favour of the Franklinian theory of a single fluid. All the common electrical machines had produced only sparks that were conducted and not ramified, and hence it might have been supposed that the spark was a combination of two sparks moving in opposite directions; but it is not easy to admit such a supposition, when the spark is known to have the form of a branch, with the twigs all pointing to one of the conductors. A translation of Van Marum's paper is published in the Annals of Philosophy for December 1820, p. 140,

8. Experiment in favour of two Fluids.M. Moll has lately performed an experiment, which has been considered as equally decisive in favour of two fluids. He places ver tically a very thin leaf of tin between two insulated horizontal rods of brass, terminated by a button, and at the distance of one or two inches. The discharge of a strong electrical battery is then made to pass from the one to the other, and the plate of tin is found to be perforated with two holes, with the burrs or ragged edges in opposite directions. Journal de Physique, Mai 1820, p. 396,

METEOROLOGY.

9. Meteorological Committee for procuring Meteorological Journals.-The great importance of meteorological observations, (particularly of thermometrical ones made twice a day, at 10 A. M. and 10 P. M.), not only in reference to the operations of agriculture and gardening, but in reference to various branches of general science, has induced the Royal Society of Edinburgh to appoint a committee of their number, not only for the purpose of establishing meteorological observations in various parts of the coast of Scotland, and along its principal valleys, but also to collect meteorological tables from all parts of the world. The following gentlemen have been named as the Committee:

We trust that the members of the Royal Society, and lovers of science in every part of the world, will second the endeavours of this committee, to obtain information so useful to their country, and to the general progress of knowledge.

10. On the Cause of Regular Figures formed by HoarFrost on Windows.-This curious phenomenon was ascribed by M. Mairan to the pre-existence in the glass of certain regular figures and lines generated during its formation, and he supposes that the particles of hoarfrost deposit themselves according to these figures. M. Carena, in a memoir Sur le Givre figurée, published in the Mémoires de Turin for 1813 and 1814, p. 56.-79. has overturned this hypothesis, and shews that the following are among the principal causes of the phenomenon. 1. The natural force of crystallization, 2, The necessity of the hoar-frost extending itself along a plane surface, which restrains the quaquaversus tendency of crystallization, 3. The numerous and varied resistances presented by the surface of the glass, 4. The imperfect and irregular conducting power of the glass, which is apt to produce in the vapours curvilineal motions at the instant preceding their congelation. M. Carena placed a small copper disc on the outside of one of the panes of glass, and found that the 'corresponding part of the glass was always free from hoar-frost.

II. CHEMISTRY.

11. Carbonic Acid, &c. found in Sea-Water.-M. Vogel has remarked, that Dr Murray and Dr Marcet have regarded seawater as more simple than it really is; and that he has evidence, that the waters of the Mediterranean and the ocean contain carbonic acid and also carbonates of lime and magnesia. Journ. de Pharmacie, tom vi. p. 378.

12. Muriate of Potash in Rock-Salt.-M. Vogel has discovered muriate of potash in the rock-salt of Berchtesgaden, in Upper Bavaria, and in that of Hallein in Salzburg. When dissolved in water, and freed, by evaporation, of the greater

part of the sca-salt which it contains, it precipitated the muriate of platinum. The precipitate, when calcined with oil, and heated with nitric acid, gave crystals of nitrate of potash. The water of the Saline of Rosenheim in Bavaria, when evaporated, likewise precipitated the muriate of Platinum. See Vol. ii. p.325. of this Journal.

In

13. Apparatus for the Combustion of the Diamond, by Mr John Murray, Lecturer on Chemistry." In the Quarterly Journal of Science and the Arts, No. 18. p. 264, 265, Mr Brande has described an apparatus for the combustion of the diamond, which is both complicated and expensive. Plate III. Fig. 10. is delineated the apparatus which I employ for this purpose. Its simplicity may be considered its chief recommendation. It represents a glass globe filled with oxygen, obtained from oxymuriate of potassa over mercury. A portion of the stem of a tobacco pipe, attached to the curved end of a wire fastened to the cork above, carries the diamond, fixed in a nidus prepared for it. The diamond is kindled by the oxyhydrogen blowpipe, or a stream of oxygen urged over the flame of a spirit of wine lamp, and then immersed into the globe. When the combustion of the diamond ceases, lime-water is passed up into the recipient, and the weight of the carbonate of lime formed and precipitated, indicates the quantity of diamond consumed."

14. On the Alloys of Platinum.-Mr Murray has favoured us with the following observations on the alloys of platinum. "While operating on antimony, I had placed a small button of that metal in a platinum spoon, and introduced it into the flame of a spirit lamp. The antimony had scarcely attained fusion, when the platinum spoon, together with it, ran into an uniform brittle mass, and fell in vivid combustion on the glass lamp, which was consequently fractured. The effect in question is prettily exhibited by wrapping up a bit of antimony in platinum foil, and holding it by a pair of forceps in the alcoholic flame, when a beautiful ignition shortly commences, and the glowing mass falls to the ground. Fragments of grained tin, arsenic, lead, bismuth, &c. folded up in platinum-foil, exhibited at the instant of fusion and combination, very brilliant and

beautiful phænomena; but the finest effect certainly was that of zinc and platinum-foil, when the fused mass emitted an intense light of a blue colour. Alloys of tin and arsenic, bismuth and lead, &c. were in like manner subjected to experiment. Laminated gold, silver and copper, proto-carburet, and per-carburet of iron, pinchbeck, &c. were rolled up in platinum-foil, and introduced into the flame, but without any particular result. Remarkable and beautiful, however, were the phænomena which appeared, when some metallic wires were brought in contact with platinum wire at a white heat in this flame. Gold, silver, and copper wires were those used. They fused in the flame, and, when brought in contact with the platinum wire, severally produced minute adhering balls, which, repeated with narrow intervals between, appeared ultimately like little glowing beads threaded on a string. These united with the platinum, and burned with very delicate scintillation; and when the wire was inclined, the beads ran along the metallic string, combining with successive films of the wire, until the latter became as fine as the almost airy thread of the gossamer. The gold, silver, and copper wires, per se, entered into tranquil fusion, and did not scintillate. When zinc is carried along the platinum wire, the ends or streams of a fine blue flame ascend from it, and when the bead rather exceeds in size, jets of a similar coloured flame issue, accompanied sometimes with slight explosion."

15. Fulminating Silver.-" In preparing some fulminating silver," says Dr Gilby, "I observed an occurrence which I have not seen any where noticed. I had placed on the table a small portion of it, to shew its detonation, and it happened, from a hole in the paper, that several other small heaps were scattered on the table; in touching one of them with sulphuric acid, I was surprised to find that they all detonated spontaneously. It is easy to imagine several reasons for the circumstance, but I am not certain as to the true one. I have frequently repeated the experiment, and always with the same result *.”

16. Iodine in the Crab and Lobster.-M. Chevreul has dis

• See this Journal, vol. I. p. 417