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flame has thus been rendered visible, the property, though in a less degree than the revolution of the eye-piece, to the right or heavy glass first tried. Rock-salt and fluorlest, more or less, will cause its extinction; spar give evidence of the power in a slight and the further motion of the eye-piece to degree; Iceland-spar, sulphate of baryta, the one side or other of this position will sulphate of lime, and carbonate of soda, approduce the re-appearance of the light, and pear to be without action on light. Almost that with complementary tints, according if not all liquids, certainly all liquids tried as this further motion is to the right or left by Dr. Faraday, showed ihe effect
. When hand. The direction in which the rotation these bodies possess a rotative power of takes place will, of course, be reversed by their own, as is the case with oil of turpenreversing either the course of the ray, or tine, sugar, tartaric acid, tartrates, &c., the the poles of the magnet. Hence it follows, effect of the magnetic force is to add to or that the polarized ray is made to rotate in subtract from their specific force, according the same direction as the currents of posi- as the natural rotation, and that induced tive electricity are circulating, both in the by the magnetism, is right or lefi-handed. helices composing the electro-magnet, and With regard to air and gaseous bodies, Dr. also as the hypothetical currents, which ac- Faraday has as yet been unable to detect cording to Ampere's theory, circulate in the exercise of this power in any one of the the substance of a steel magnet. The laws substances in this class. A vast number of this action may perhaps be best enunci- of gases as well as air were submitted to exated in the language of the author :- periment, but they all gave negative results.
From the relation which we have pre“ Magnetic lines then, in passing through viously shown exists between the two forces, silicated borate of lead, and a great number of magnetism and electricity, the probability other substances, cause these bodies to act that an electric current would give the upon a polarized ray of light, when the lines
same result of action on light, as a magnet, are parallel to the ray, or in proportion as they are parallel to it; ir ihey he perpendicular to must be apparent to the most casual reader. the ray, they have no action upon it. They This was tried by the discoverer with sucgive the diamagnetic the power of rotating the cess; a quantity of covered copper wire, ray; and the law of this action on light is, that wound in the form of a helix, supplied a if a magnetic line of force be going from a forın of apparatus, in which great lengths north pole, or coming from a south pole, along of diamagnetics, such, for example, as wathe path of a polarized ray, coming to the ob. ter in a long glass tube, and especially of server, it will rotate that ray to the right hand; or, that if such a line of force be coming from such bodies as appeared to be but little afa north pole, or going from a south pole, it will fected between the poles of the magnet, rotate such a ray to the left hand."
could be submitted to examination, and
their effect exalted. The electric current We cannot, within our limits, follow Dr. passed through the helix was in all the exFaraday through all the well-contrived and periments derived from a battery of ten lucidly described experiments by which the pairs of Grove's plates. A tube within the inquiry was pursued. We must content helix being filled with distilled water was ourselves with enunciating the different cir- placed in the line of the polarized ray, so cumstances which affect, limit, and define that by examination through the eye-piece, the extent and nature of this new power of the image of the lamp-flame produced by action on light. In the first place, the ro- the ray could be seen through it. The eyetation appears to be in proportion to the piece being turned so that the image of the extent of the diamagnetic through which the fame could no longer be seen through it, ray and magnetic lines pass. The power and the battery being connected with the of rotating ihe ray of light increases with helix, the image of the flame instantly rethe intensity of the magnetic lines of force. appeared, and continued as long as the elecOther bodies, besides the heavy glass, pos- tric current was passing through it; on sess the same powers of becoming, under stopping the current, the image disappeared. the influence of magnetic force, active on The light does not rise up gradually, as in light; though, if all transparent bodies pos- the case of electro-magnets, but instantly. sess the power of exhibiting the action, In this experiment it cannot be doubled they have it in very different degrees; and that a ray of light is electrified, and the magup to this time there are some that have not netic resultant of the electric forces illushown it at all; glass made of the borate of minated. lead, flint-glass, crown-glass, all exhibit the The law of this action of electricity is as
simple and beautiful as that we have already stance, rendered visible by the light, and this described in reference to the effect of the was what I meant by illumination.” magnet-and for its description we will again quote from the Researches :
But, although the experiments and ex
pressions of Faraday have not established, “When the current was sent round the helix or been intended by the author to establish in one direction, the rotation induced upon the the fact, that the lines of magnetic force ray of light was one way; and when the cur- ure luminous, yet this assertion has been rent was changed to the contrary direction, the boldly made by Baron Reichenbach, in the rotation was the other way. In order to express the direction, I will assume, as is usually We are aware that we are treading on dan
“Researches on Magnetism" before us. done, that the current passes through the acid to the platinum in the same cell: if such a gerous ground; we are approaching the current pass under the ray towards the right, confines of the oft-debated and much ridi. upwards on its right side, and over the ray to- culed science of animal magnetism. The wards the left, it will give the left-handed rota- facts detailed in his volume are startling, tion to it; or if the current pass over the ray to and will probably be received in England the right, down on the right side and under it with incredulity; but it must also be retowards the left, it will induce it to rotate to the right hand.' The law, therefore, by which membered, that the name of Reichenbach an electric current acts on a ray of light is is familiar to chemists for many laborious easily expressed. When an electric current researches and important discoveries; and passes round a ray of polarized light in a plane his character as an experimentalist has perpendicular to the ray, it causes the ray to always stood particularly high for minute revolve on its axis as long as it is under the
accuracy and untiring perseverance. These influence of the current, in the same direction researches, moreover, were published in a as that in which the current is passing."
journal standing in the highest rank among All bodies are affected by helices as by Chemie und Pharniacie.'
chemical periodicals, the 'Annalen die
We are, of magnets, and according to laws which show that the causes of the action are identical course, far from vouching for the truth of as well as the effects . And although hith-them generally known, under the hope that
the facts; our object is simply to make erto the magnetic and electric forces appear the experiments may be repeated and tested to exert no power on the ordinary or depo- by those to whom the opportunity may prelarized ray of light, we can hardly doubt but that they have some special influence, the volume, justly remarks, that “in mat
sent itself. Dr. Gregory, the translator of which probably will soon be made apparent iers of observation, especially when new, by experiment'; neither can it be supposed the only question is this, 'It it true ? and otherwise than that the same kind of action
not 'Is it possible ?' or 'Is it absurd ?' should take place on the other forms of
We cannot say what is possible, and no radiant agents, as heat and chemical force.
facts can be absurd.” A few words are necessary ere we quit
Reichenbach, then, asserts that from nuthis part of the subject, relative to the title of the paper under consideration, or rather merous experiments he has discovered, that to the latter portion of it—we mean the ex. at the poles and sides of powerful magnets pression, “Illumination of lines of the
there is an appearance of light, visible only magnetic force.” Many persons anticipa- from the work will explain what he means
to the sensitive. The following quotation ted, and it has even been boldly asserted, by the sensitive :that they have been rendered luminous. Such a meaning was never intended by the
“Diseased sensitive subjects experience difauthor; and in an explanatory note, ap- ferent sensations (when a magnet is drawn pended to the paper, he says that :
down the body), often disagreeable, and occa
sionally giving rise to fainting, to attacks of “He intended to express that the line of catalepsy, or to spasms so violent that they magnetic force was illuminated, as the earth might possibly endanger life. In such cases, is illuminated by the sun, or the spider's web which generally include somnambulists, there illuminated by the astromomer's lamp. Em- occurs an acuteness of the senses: smell and ploying a ray of light, we can tell
, by the eye, taste, for example, become astonishingly delithe direction of the magnetic lines through a cate and acute; many kinds of food become body; and by the alteration of the ray, and its intolerable, and the perfunies, most agreeable optical effect on the eye, can see the course of at other times, become offensive. The patients the lines just as we can see the course of a hear and understand what is spoken three or thread of glass, or any other transparent sub- four rooms off, and their vision is often so irri
table, that, on the one hand, they cannot en-la lens, and the inverted image accurately dure the sun's light or that of a fire ; while, on described, and its position pointed out by the other, they are able in a dark room to dis- the sensitive patients. tinguish not only the outlines, but also the colors of objects, where healthy people can
The question naturally arises, how is it not distinguish any thing at all. Up to this that the magnetic light and flame are ordipoint, however strange the phenomena, there marily invisible. It is thus answered by the is nothing which cannot easily be conceived, author :since animals and men differ very much in the acuteness of the senses, as is daily experi
6 That it is invisible to ordinary eyes is not enced.”
wonderful, when we reflect that the sun's light,
according to Wollaston, is 5,560 times, accordIt was with six such sensitive patients ing to Leslie, even 12,000 times as poweriul as that the experiments were made: to one the light of a candle; that many flames, as and all of them, there appeared in the dark, those of alcohol or pure hydrogen, are invisia luminosity like a moving flame at the poles ble not only in the sun's light, but in strong and around powerful magnets : the vivid- daylight. Froin these latter to entire invisiness of the luminosity varied in all the bility to ordinary, eyes, even in the dark, is a cases, according to the degree of sensitive step easily conceived." ness and the diseased state of the body.
It has been a well-known scientific fact, This phenomenon was only apparent when that the magnetic needle suffers a very great the armature of the magnet was removed, disturbance both before and on the appearand ceased when it was replaced. A bar, ance of the aurora borealis; and on some horse-shoe, and electro-magnet all presented occasions even a deviation of 8° has been the same appearances; in the last, however, observed. Arago has noticed that at Paris, it was the most distinct, in the first it was the needle was affected by auroræ that most faint. The phenomenon in all these
were seen in Scotland; and so striking is cases presented the appearance of a flame, the connexion between the two classes of with a play of colors shooting out rays as facts, that the existence of the aurora could large as the magnet, and a general weaker be inferred from the derangements of the light over the whole surface, at the junction needle. The real nature of the aurora has of the plates of which the magnet itself was never been clearly determined, although it composed. To test still further the pheno- is generally conceived to be dependent on menon, recourse was had to the following electricity. Reichenbach, however, conexperiment. A very sensitive daguerreo-ceives, from the result of the experiments type plate was placed opposite to a magnet we have narrated, that they are visible in a closed box, surrounded with thick bed
magnetic lights. clothes, so that no ordinary light could enter. After sixty-four hours' exposure, the - The similarity of the light,” he observes, plate, when held over mercurial vapor, as seen by Mademoiselle Reichel (one of his was found fully affected, as by light, over sensitive patients), to the aurora is striking, the whole surface. To this experiment, and it must be borne in mind that the aurora, however, there are, to our minds, two strong affects the needle very strongly; just as the
or the magnetism of the earth producing it, objections. The first of these is, that heat, magnet used by the author and giving out electricity, galvanism, produce impressions light, visible to sensitive persons, did also.” analogous to those of the sun's rays, and, therefore, the effect of magnetism on the He is far from considering their identity prepared plate may be entirely independent as proved, because between light which is of this pretended luminosity. Again, the visible to healthy eyes and that which is incolor of the luminous flame of magnets is visible there is a gap not easily filled up. described as red. Now it is well known by But at least the analogy is so great, that all who have practised the photographic their identity acquires a high degree of proart, that the red rays of the spectrum are bability. inert on chemical compounds, the rays at We now turn to the consideration of the the opposite end of the spectrum being the second part of the researches of Faraday, only agents in the production of daguerreo contained in the 20th and 21st series of the type effects. This fact appears to us most Experimental Researches in Electricity,' strongly to militate against this experiment under the title of New Magnetic Actions as a proof of the luminosity. Another ex- and the Magnetic Condition of Matter.' periment is stated to have been made, in The phenomena which we shall now have which the magnetic light was condensed by to describe are altogether different in their nature from those we have previously (netic force which the body when reduced benoticed; they prove not only a magnetic neath it could acquire. In this view, iron and condition of the substances referred io, un nickel were not considered as exceptions from known, and even unsuspected before, but he metals generally with regard to magnetalso many others, including a vast number ered as an exception from this class of bodies
ism, any more than mercury could be considof opaque and metallic bodies, and perhaps as to liquefaction.” all except the magnetic metals and their compounds.
And they also present us In consequence of this opinion, he made with the means of undertaking the corre- experiments on the point. The metals tried Jation of magnetic phenomena, and perhaps were arsenic, antimony, bismuth, cadmium, the construction of a theory of general cobalt, chromium, copper, gold, lead, mermagnetic action founded on simple funda- cury, palladium, platinum, silver, tin, zinc, mental principles.
as also plumbago; they were all exceed. We have already said that since the ingly reduced in temperature, but in none period of Coulomb's experiments previ- of these cases could he obtain the least inously referred to, a general impression has dication of magnetism. His present reprevailed amongst philosophers that all sub- searches have now revealed to us the cause stances were acted on by magnets, in the of failure. same manner as iron, nickel, &c., though But though this opinion was so prevathis influence was very different in degree. lent, facts were not wanting to cast over it Coulomb's experiments were carried on in a shade of doubt; Coulomb himself ob1802, and in that year he announced as an served that a needle of wood, under certain incontrovertible fact, that all substances conditions, pointed across the magnetic whatever, when formed into small needles, curves ; and it is also mentioned by turned themselves in the direction of the Becquerel, that a needle of wood placed poles of the magnets, and after a few oscil itself parallel to the wires of a galvanomelations, finally settled in that position. ter. These effects, however, were referred Gold, silver, brass, wood, and all other sub- by the latter philosopher to a degree of stances, whether organic or inorganic, ac- magnetism less than that of the tritoxide of cording to him, in this way obeyed the iron, but the same in character, for he power of magnets. In the present state of makes the following remarks :our knowledge, we can only explain the experiments, by supposing that all the bodies 6 This difference of effect, which established which he tried, and which he deemed sus- a line of demarcation between these two speceptible of magnetism, were impure, and cies of phenomena, is due to this, that the contained, either minute quantities of iron, of iron, wood, &c., ive may neglect the reac
magnetism being very feeble in the tritoxide or other magnetic metals, which gave them tion of the body on itself, and therefore the their susceptibility. So universal was the direct action of the bar ought to overrule it." reliance placed upon these experiments of Coulomb, that even the author whose re- In 1829, M. le Bailiff, of Paris, showed cent discoveries have disproved this long that both bismuth and antimony repelled prevailing belief entertained the same opin- the magnetic needle, and even long before ion. In the London and Edinburgh Philo- this, in the year 1778, the repulsion of bissophical Magazine, for March, 1836, the muth by a magnet was observed by Brugfollowing remarkable passage is from a It is an astonishing fact that this paper by Dr. Faraday :
experiment should have so long remained “General views have long since led me to dent that it must have been considered as a
unnoticed, and without results. It is evian opinion, which is probably also entertained by others, that all the metals are magnetic in peculiar and isolated fact, and not the conthe same manner as iron, though not at com-sequence of a general property which is mon temperatures, or under ordinary circum- now shown to belong to all matter. stances. I do not refer to a feeble magnetism, With these preliminary remarks, which, uncertain in its existence and source, but to a however, were necessary for the appreciadistinct and decided power, such as that pos- tion of the novelty and merit of the present sessed by iron and nickel; and my impression discovery, we proceed at once to its enunhas been that there was a certain temperature ciation. All matter is subject to the magfor each body beneath which it was magnetic, but above which it lost that power; and fur- netic force, as universally as it is to the ther, that there was some relation between this gravitating, the electric, the cohesive, and point of temperature and the intensity of mag-| the chemical forces; but this influence is
not in all cases, as was formerly believed, mutton, beef, blood, leather, apple, bread, of the same character as that exerted upon nay, if a man could be suspended with iron; on the contrary, different bodies are sufficient delicacy and placed in the magacted upon by the magnetic forces in two netic field, he would be repelled and point different and opposite ways; and they may equatorially; for all substances of which he accordingly be conveniently divided into is composed, including the blood, possess two classes.
The first class is that of this property. which iron is the type; the bodies belonging to it, which are somewhat limited, are “Having arrived at this point,” observes called MAGNETICS; when suspended be- Mr. Faraday, “I may observe that we can tween the poles of an electro-magnet so as
now have no difficulty in admitting that the to swing freely, they are attracted by the of a magnetic property in matter, new to our
phenomena abundantly establish the existence pole to which they may happen to be near, knowledge. Not the least interesting of the est, and if allowed to oscillate, they will consequences that flow from it is the manner ultimately take up a position coincident in which it disposes of the assertion that all with the direction of the magnetic forces, bodies are magnetic. Those who hold this or in other words, in a straight line between view mean, that all bodies are magnetic as the poles of the magnet; this direction the iron is, and say that they point between the author calls the arial position. To this roles. The new facts give not a mere nega
iive to this statement, but something beyond, class belong all those metals which have namely, an affirmative as to the existence of hitherto been termed the magnetic metals, forces in all ordinary bodies directly the oppoas iron, nickel, cobalt, as well as many site of those existing in magnetic bodies, for other bodies hithertu regarded as unmag- whereas those practically produce attraction, netic, as for example, peroxide of iron, these produce repulsion; those set a body in paper, sealing-wax, China ink, Berlin por- an equatorial position: and the facts, with re
the axial direction, but these make it take up celain, plumbago, tourmaline, charcoal, gard to bodies generally, are exactly the re&c. In addition to the metals already verse of those which the view quoted indiknown to be magnetic, the following have cales.” by these experiments been also proved to be so; titanium, manganese, cerium, chromi- There are some other circumstances in um, platinum, palladium. The second reference to these two actions of magnets great class of bodies are found, in direct on all substances which are extremely inopposition to the former, to arrange them- teresting, and consequently must not be. selves in right angles to the magnetic passed over in silence. To whichever class poles, and consequently to the magnetic a substance belongs, its compounds and lines of force, a position in which they re- salıs also belong. Thus iron is magnetic; main, as long as the power of the magnet is so are its salts and native compounds.
This position the author calls the Green bowie-glass and crown-glass are both equatorial direction. All these bodies, too, magnetic, from the iron they contain. Flintare repelled from either pole of the mag. glass and the heary glass already named net, the law in this respect being, that all are diamagnetic, for they contain no iron. such substances are repelled from the Bismuth is diamagnetic; its salts and com. stronger to the weaker points of action. pounds are likewise so. But we may adTo this class the title of DIAMAGNETICS is vance a little further : not only are the salts given, and of it bismuth may be considered of substances acted on in the same way as the type. The bodies belonging to it are their base, but the solutions of these salts exceedingly numerous: of the meals the even obey the same mysterious power.
A following have been found to be diamag- tube, for example, filled with a clear solunetic: lead, bismuth, arsenic, iridium, urani- tion of proto or persulphate of iron, is um, tungsten, silver, antimony, sodium, attracted by the poles, and points well in an magnesium, calcium, strontium, barium, axial direction. The magnetic properties potassium, gold, copper, cadmium, mer- of compound bodies depend on those of cury, tin, zinc. To this class also belong their elements; and the bodies are rensubstances so widely differing in properties dered either magnetic or diamagnetic acas those contained in the following list. cording to the predominance of one or Glass, crystalline bodies, whether belong other of these conditions among their coning to the single or double refracting class, stituent parts. In one respect, the diaphosphorus, sulphur, water, alcohol, ether, magnetic action presents a remarkable conoils, caoutchouc, sugar, starch, wood, ivory, trast to the magnetic, and the difference is Včl. IX. No. I.