nected one above the other in such a way that the first is emptying itself when the second is in distillation.

In the largest arrangement of the kind constructed by MM. Leplay and Co., the three cylinders are each 3-40 meters high and 1.42 in diameter. They contain 12 diaphragms. Each charge of a cylinder contains 2,500 to 2,800 kil. of beets. In twenty-four hours, the distillation and emptying of fourteen cylinders may be done, corresponding to 35,000 to 40,000 kil. of beets. Two such apparatuses, distilling 9 million kilograms of beets have been kept in operation at Douvrin during the last harvest. This method has been put in practice also in other parts of France and in Belgium. We have not room for more details; we add only that the residue or pulp is much sought for by those who raise cattle, and the animals eat it with avidity.

It is apparent that the principal merit in the process is in its not requiring the rasp or the press, and its obtaining the alcohol at the first nearly pure. In this way, too, the viscous, acetic or putrid fermentation is avoided, and consequently a vat charged with beets may be kept for fifteen days without loss or injury, while in the fermentation of the juice an alteration often takes place even in twenty-four hours.

Paris:

Bibliography.- Visite à l'Exposition Universelle de Paris in 1855, par MM. TRESCA, PELIGOT, SILBERMANN, etc., 1 vol. in 12 mo. chez Hachette. We have neither time nor space for describing the Exhibition at Paris; but there is here a book costing only 3 francs, giving an account of each object exhibited, and a history of each invention. The names of the authors guarantee exactness and fidelity in all facts and details.

Precis de Chemie Industrielle, par A. PAYEN, 3d edit., in 1 vol. 8vo., of 1070 pages, with an atlas. Paris: chez Hachette.-Since the publi cation of the first edition of this work, all the technological journals have drawn freely from its pages; for as Professor of Chemistry in the Conservatory of Arts and Trades at Paris, M. Payen is in the way to know better than any one else in France, all that relates to the newest results in industrial chemistry in his own and other countries. Two editions have successively been exhausted within a short time. The third was called for, and the Paris Exhibition has enabled the author to give it greater completeness. It contains special details upon caoutchouc, gutta percha, illuminating gas, manufacture of paper, chemical matches, starch, sugar, artificial soda, the fatty bodies, sulphuric acid, phosphorus, etc. etc.

Des Substances Alimentaires, by M. PAYEN, in 12mo. Paris: price three francs. This work written for the people and for artisans who have little knowledge of chemistry, is especially interesting for the methods which it gives for improving articles of food, preserving them, or detecting adulterations, etc.

Leçons de Chémie générale élémentaire, par M. CAHOURS, 2 vols. in 12mo. Paris: chez Mallet-Bachelier.-These lessons are arranged after the lectures which M. Cahours delivers at the "Ecole Centrale des Arts et Metiers" as successor to Dumas. A clear, simple and methodical style characterises this small work, in which we recognise the able instructions of M. Dumas, worked up by one of the most distinguished of his students.

SCIENTIFIC INTELLIGENCE.

I. CHEMISTRY AND PHYSICS.

1. On the Effect of Chlorine in Coloring the Flame of Burning Bodies; by D. FORBES, F.G.S., F.C.S., A.I.C.E., (L., E. and D. Phil. Mag., xi, 65.)—A considerable time back, while examining some saline minerals for boracic acid, and employing the usual test as to the power of coloring flame green, when treated with sulphuric acid and alcohol, it was found that a green flame presented itself, very similar to that which would be expected in case boracic acid were present in the minerals. On the most careful examination, however, no traces of boracic acid could be detected, and it was evident that the coloration of the flame must have proceeded from some other source.

As chlorine was present in considerable amount in the minerals in question, it became interesting to see whether its presence might have produed the green color; and the experiments made on the subject fully confirmed this view. A number of other experiments on the power possessed by chlorine to color flame, led to the following conclusions, which are stated briefly, as the results themselves sufficiently explain the modus operandi.

Chlorids treated with concentrated sulphuric acid and a very small amount of alcohol produced green flames similar to those eliminated from borates under like treatment. Quantitatively, however, the flames were of less intensity; that is, the same weight of a borate would produce considerably darker green flames than when a chlorid was used.

When chlorids were moistened with sulphuric acid and heated in the blowpipe flame, a faint green coloration was observed, which generally confined itself to the inner flame.

When hydrochloric acid is dropped cautiously on the flame of burning alcohol, a greenish tinge is observable.

A jet of chlorine or of hydrochloric acid gas directed upon the flame of a spirit-lamp or of coal-gas. produces a jet of green flame; this was also found to be the case when (by means of a convenient burner) chlorine gas was passed into the centre of a flame of burning coal-gas, or of vapor of alcohol.

When burning alcohol was injected into a globe filled with chlorine gas, the alcohol vapor continued burning at the mouth of the globe with a very flickering but often brilliant green flame.

From the above experiments, it will be seen that chlorine has in itself a decided coloring action on the flames of burning bodies, which may consequently in some cases lead to its being confounded with boron, as the green color imparted to flame has hitherto been regarded as a most characteristic test of the latter element. When, as often happens, chlorine and boron occur together, this test consequently becomes nearly valueless.

2. On some points of Magnetic Philosophy; by Prof. FARADAY, D.C.L., F.R.S., (Proc. Roy. Inst. of Great Britain, Jan. 1855, p. 6.)—The magnetic and electric forms of power being dual in their character, and

also able to act at a distance, will probably aid greatly in the development of the nature of physical force generally and if (as I believe) the dualities are essential to the forces, are always equal and equivalent to each other, and are so mutually dependent, that one cannot ap. pear, or even exist, without the other, the proof of the truth of such conditions would lead to many consequences of the highest importance to the philosophy of force generally. A few brief experiments with the electric power quickly place the dual cases before the contempla. tive mind. Thus, if a metallic vessel, as an ice-pail, be insulated and connected with a delicate gold leaf electrometer, or other like instrument, and then an insulated metallic globe, half the diameter of the ice-pail, be charged with positive electricity and placed in the middle of the pail, the latter being for the moment uninsulated by a touch outside, and then left insulated again, the whole system will show no signs of electricity externally, nor will the electrometer be affected: but a carrier applied to the ball within the vessel will bring away from it positive electricity, showing its particular state of charge; or being ap plied to the lower inside surface of the vessel will bring away negative electricity, proving that it has the contrary state: or the duality may be proved by withdrawing the ball, when the vessel will show itself negative by the electrometer, and the ball will be found positive. That these dualities are equal, is further shown by replacing the ball within the vessel, observing the electrometer, bringing the ball and vessel in contact, and again observing the electrometer, which will remain unchanged; and finally withdrawing the ball, which comes away perfectly discharged, and leaves the vessel externally in its unchanged and previous state. So the electric dualities are equal, equivalent, and mutually sustained. To show that one cannot exist alone, insulate the metallic vessel, charge it strongly by contact with the machine or a Leyden jar, and then dip the insulated ball into it; and after touching the bottom of the vessel with the ball, remove it, without touching the sides it will be found absolutely free from charge, whatever its previous state may have been; for none but a single state can exist at the bottom of such a metallic vessel; and a single state, i. e., in an unrelated duality, cannot exist alone.

The correspondent dualities, i. e., the northness and the southness of the magnetic force are well known. For the purpose of insulating, if possible one of these, and separating it in any degree from the other, numerous experiments have been made. Thus six equal electro-magnets, formed of square bars, were put together in the direction of three lines perpendicular to each other, so that their inner ends, being all alike in polarity, might inclose a cubical space and produce an experi mental chamber. When excited, these magnets were very powerful in the outer direction, as was found by nails, filings, spirals, and nee. dles; but within the chamber, walled in on every side by intense north poles, there was no power of any kind: filings were not arranged; small needles not affected, except as they by their own inducing powers caused arrangement of the force within; revolving wire helices produced no currents: the chamber was a place of no magnetic action. Ordinary magnetic poles of like nature produced corresponding results. A single pole presented its usual character, attracting iron, repelling

bismuth; a like pole, at right angles to it, formed a re-entering angle, and there a weak pole of magnetic action was caused; iron was attracted from it to the prominent corners; bismuth moved up into it; and a third like pole on the opposite side made the place of weak force still weaker and larger; another pole or two made it very weak; six poles brought it to the condition above described. Even four poles, put with their longer edges together, produced a lengthened chamber with two entrances; and a little needle being carried in at either entrance passed rapidly through spaces of weaker and weaker force, and found a part in the middle where magnetic action was not sensible.

Other very interesting results were obtained by making chambers in the polar extremities of electro-magnets. A cylinder magnet, whose core was 1.5 inches in diameter, had a concentric cylindrical chamber formed in the end, 0·7 in diameter, and 1.3 inches deep. When iron filings were brought near this excited pole, they clung around the outside, but none entered the cavity, except a very few near the outer edge. When they were purposely placed inside on a card they were quite indifferent to the excited pole, except that those near the mouth of the chamber moved out and were attracted to the outer edges. A piece of soft iron at the end of a copper wire was strongly attracted by the outer parts of the pole, but unaffected within. When the chamber was filled with iron filings and inverted, the magnet being excited, all those from the bottom and interior of the chamber fell out; many, however, being caught up by the outer parts of the pole. If pieces of iron, successively increasing from the size of a filing to a nail, a spike, and so on to a long bar, were brought into contact with the same point at the bottom of the inverted chamber, though the filing could not be held by attraction, nor the smaller pieces of iron, yet as soon as those were employed which reached to the level of the chamber mouth, or beyond it, attraction manifested itself; and with the larger pieces it rose so high that a bar of some pounds. weight could be held against the very spot that was not sufficient to retain an iron filing.

These and many other results prove experimentally, that the mag. netic dualities cannot appear alone; and that when they are developed they are in equal proportions and essentially connected. For if not essentially connected, how could a magnet exist alone? Its power, evident when other magnets, or iron, or bismuth is near it, must, upon their removal, then take up some other form, or exist without action : the first has never been shown or even suspected; the second is an impossibility, being inconsistent with the observation of force. But if the dualities of a single magnet are thrown upon each other, and so become mutually related, is that in right lines through the magnet, or in curved lines through the space around? That it is not in right lines through the magnet (it being a straight bar or sphere) is shown by this, that the proper means as a helix round the magnet, shows that the internal disposition of the force (coercitive or other) is not affected when the magnet is exerting its power on other magnets, or when left to itself (Experimental Researches, 3119, 3121, 3215, &c.); and like means show that the external disposition of the force is so affected: so that the force in right lines through the magnet does not change under the circumstances, whilst the force in external (and necessarily) curved lines does.

The polarity of bismuth or phosphorus in the magnetic field is one point amongst many others essentially dependent upon, and highly illustrative of the nature of, the magnetic force. The assumption that they have a polarity the reverse of that of paramagnetic bodies involves the consequence, that northness does not always repel northness or attract southness; or else leads to the assumption that there are two northnesses and two southnesses, and that these sometimes associate in pairs one way, and at other times in the contrary way. But leaving the assumptions and reverting to experiment, it was hoped that a forcible imitation of the imagined state of bismuth in the magnetic field, might illustrate its real state, and, for this purpose, recourse was had to the indications given by a moving conductor. Four spheres of copper, iron, bismuth, and hard steel have been prepared, and rotated upon an axis coincident with the magnetic axis of a powerful horse-shoe magnet; each sphere has a ring of copper fixed on it as an equator, and the ends of a galvanometer wire were brought into contact with the axis and the equator of the revolving globe. Under these circumstances, the electric current produced in the moving globe was conveyed to the galvanometer, and became the indicator of the magnetic polarity of the spheres; the direction of rotation, and the poles of the magnet, being in all cases the same. When the copper sphere, as a standard, was revolved, deflection at the galvanometer occurred in a certain direction. When the iron sphere replaced the copper and was revolved, the deflection at the galvanometer was the same. When the bismuth sphere was employed, the deflection was still the same-and it still remained the same when the steel sphere was rotated in the magnetic field. Hence, by this effect, which I believe to be a truthful and unvarying indication of polarity, the state of all the spheres was the same, aud therefore the polarity of the magnetic force in the iron, copper, and bismuth, in every case alike (Exp. Res. 3164, &c.). The steel sphere was then magnetized in the direction of its axis, and was found to be so hard as to retain its own magnetic state when in a reverse direction between the poles of the dominant magnet, for upon its removal its magnetism remained unchanged. Experiments were then made in a selected position, where the dominant magnet force was not too strong -(a magnet able to lift 430 lbs. was used)-and it was found that when the steel magnet was placed in accordance, i. e., with its north pole opposite the south pole of the dominant magnet, the deflection was in the same direction as with the bismuth sphere: but when it was changed so as to be in the magnetic condition assigned by some to bismuth (i. e. with reversed polarities), it then differed from bismuth, producing the contrary deflection.

It is, probably, of great importance that our thoughts should be stirred up at this time to a reconsideration of the general nature of physical force, and especially to those forms of it which are concerned in actions at a distance. These are, by the dual powers, connected very intimately with those which occur at insensible distances; and it is to be expected that the progress which physical science has made in latter times will enable us to approach this deep and difficult subject with far more advantage than any possessed by philosophers at former periods. SECOND SERIES, Vol. XXI, No. 62.-March, 1856.

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