charged with the flocky precipitate of which I have just spoken. The fleeces of this precipitate, by reason of their size, are more easily observed than the particles of clay. It happens sometimes that these flocks suspended in water, in place of describing in their movement the ovoïde curves of which I have above spoken, rest near the piece of camphor, and there, at of a millimetre distant from this piece, they present a rapid rotatory movement on themselves, and on a horizontal axis, sometimes in one direction and sometimes in an opposite one. There is here, however, no change in the direction of the rotation; when that is established in one direction it persists in it. There exists then at one or two tenths of a millimetre around the particle of camphor a rotatory moving force, the direction of which is not the same at all points of its periphery; the corpuscles floating in the water, and which are attracted by the camphor, all receiving on arriving near it, this rotating movement on themselves, whilst at the same time they receive the movement of repulsion. They promptly lose this rotating movement on retreating from it, and that by the effect of the resistance which the water subjects them to by reason of their irregularity of form; they would probably retain this rotatory movement during their revolution, if their form was perfectly spherical. As for the rest, it is evident that the rotation of the corpuscles themselves and their revolution in a limited curve, are two modifications of the same phenomenon. In fact, the two moities of the revolution, the first of which is due to attraction and the second to repulsion, are, in relation to each other, just the same as the two moities of the rotation are to each other: of which the first, which is analogous to that moiety of the revolution due to attraction, commences at that part of the turning body actually opposed to the camphor, and finished in regard to the latter; and the second, analogous to that moiety of the revolution due to repulsion, commences with regard to the camphor, and finishes at the opposite place.

17. It results from these observations that the movement of rotation is here a modification of the movement of revolution. The cause of these two movements is the same. Another result, also, is that the attraction and repulsion are here the two opposite directions of the same force, which are exercised according to a limited or closed curve,-a curve whose greater axis corresponds by one of its extremities with the neighbourhood of the body in which is found the origin of this force.

18. Hitherto I have not studied the movements which the camphor impinges on the particles suspended in the water, and that thus it only acts on this liquid upon one of its sides. It was important to observe what happened when the camphor is situated on the surface of the water which environs it circularly. It is not easy to make this observation with the microscope, because the piece of camphor placed on water is generally animated by a progressive movement. But it often happens that this progressive movement, after having lasted for some time, ceases; the piece of camphor may

then rest in its place in the middle of the water, being agitated solely by a slight trembling movement. We may then easily observe by the microscope the effects which it produces. We do not see in this case the two vortices, with opposite directions, which are constantly observed in the movements of light bodies suspended in the water, when the camphor is fixed at the edge of the liquid; we then see these light bodies precipitated equally on all sides on the piece of trembling camphor, and they there receive also the movement of repulsion which always takes place in a different direction to that in which is produced their movement of attraction, in such a manner that in returning incessantly towards the camphor, from which they afterwards retreat, they describe limited and ovoïde curves which are extremely multiplied, and which appear to cross each other in all directions. I have also observed, in this case, the movement of rotation of large flocks situated at a very small distance from the camphor. I put water charged with argillous particles in suspension in a saucer, and at the height of some millimetres, I suffered the argillous particles to be precipitated to the bottom of the water; I then put a piece of camphor on the surface of this liquid, now become limpid. On observing it through a magnifier, I saw the pulverated argillous sediment raised from the bottom of the vessel, especially in those parts where the piece of camphor was transported to, and when the latter remained in one place by turning on itself, the argillous sediment being raised by its attraction turned with it, thus forming a sort of small truncated waterspout whose base is at the bottom of the vessel.

19. On the inspection of these phenomena, no one will doubt that they are due to electricity; but we may be permitted to ask, if these same phenomena are explicable by means of any facts known to science. The attraction and repulsion of light bodies only belongs to static electricity, again they produce this effect in the air only, and not at all in water. Some phenomena of rotation are produced under several circumstances by electro-magnetism; but in the experiments here under consideration, the phenomena of rotation takes place without the intervention of magnetism. I ought, however, to abstain from pronouncing on this question, and I will now pursue my observations.

20. The actions of attraction and repulsion which camphor exercises on light bodies floating in water, are here the indices that these same actions are exercised on the water itself; they are, then, the principal causes of movement which are presented by camphor; it attracts and repulses alternately the water which surrounds it; it ought to be moved then, at the same time as the water, and even more than it, since it is more moveable. It is from the rapid and continual succession of these two opposite actions that the trembling movement presented by camphor results; its turning ought to be attributed according to my observations, to the fact that the piece of camphor, when turning, possesses a lateral point, on which the ele ctric repulsive effluvia especially operates; and which, by reaction

makes the piece of camphor turn on itself by the same mechanism which causes the rotary movement in a pyrotechnic sunflower. The sudden and jerking, and I may say too, almost capricious movement which the piece of camphor presents on the water, in all sorts of directions, is the result sometimes of reciprocal repulsion which exists between it and the water, and sometimes of their reciprocal attractions, according to the accidental predomination of one or the other of these two actions. To this cause of movement is joined the effect of recoil which results from the repulsion which the piece of camphor exercises on the superficial solution, as it has been already explained in this paper. I have shown how this superficial solution is repulsed by the piece of camphor; likewise, that all the solutions are repelled by the soluble bodies from which they emanate. Now, as it is proved here that the piece of camphor possesses an electric state, a source of attractions and repulsions, it ought no longer to appear doubtful that the repulsion which it exercises on its superficial solution is due to electricity; besides this, it is this electricity which is the cause of the more rapid evaporation of camphor when it is placed in water than when it is placed on another body, as Benedict Prévost and Venture have shown by experiment. This electricity, and the effects which are derived from it, are observed when even in contact with all the oily, greasy, or resinous bodies, when these bodies can undergo a solution, whether penetrating or superficial on this liquid. Thus, the particles of soap brought into contact with water charged with argillous particles in suspension, and placed under the microscope, present exactly the same electric phenomenon, and even with much more intensity; for the effects of attraction and repulsion on the argillous particles are extended much farther in the interior of the water; the field of the most feeble microscope cannot then show, in all their extent, the vortices or whirlpools which are produced under these circumstances. It is remarkable, that the rapid and concentric afflux of the water, and the argillous particles which it holds in suspension, towards the piece of soap, commences at the instant even of the contact of the latter with the water; the phenomenon of repulsion succeeds to the phenomenon of attraction and is thus only secondary. I have observed these same electric phenomena of attraction and repulsion to be successive, and forming thus whirlpools in the water, by bringing into contact with this liquid pieces of cork soaked in essential oil of turpentine or alcohol; but these phenomena had only a very short duration, in consequence of the rapidity with which the solution was then accomplished. Also, all the oily bodies, or more generally, all combustible bodies, susceptible of being united with water by penetrating or superficial solution, take, from the time of their contact with water, an electrical state which is the cause of the repulsion which they exercise on their own solutions, which thus possesses the same electricity, or is in the same electrical state as themselves. It is by virtue of this same state of electricity that combustible bodies exercise on the water and on the solid particles which it holds in

cc

suspension, those attractions and repulsions which, by their succession, form whirlpools or vortices.

21. It remains for us to know for a certainty whether the alkalies, the acids, and the salts, which also possess the property of moving on water, because they repel their solutions, also present the whirlpools resulting from successive attractions and repulsions exercised on the surrounding water, and on the light bodies which they hold in suspension. As the alkalies present in a far higher degree than the acids and salts the property of moving on the water, it will be on them that I shall here found my observations. I have already explained above, the experiment that showed me the fact, that a small fragment of caustic soda immersed, under the microscope, in water charged with argillous particles, presents the centrifugal movement of its solution, which flies from it on every side. I have made this experiment with spring water. Now, on the solution of soda in this water, there was a large number of bubbles of gas disengaged, which, like the solution, obeyed the centrifugal movement, and which were an obstacle to the distinct vision of that which was taking place around the small fragment of soda in course of being dissolved. In order to avoid this inconvenience, I made use of water which had been deprived of air and carbonic acid by ebullition. I put into it the argillous particles in suspension. A small fragment of caustic soda was placed in this water, under the microscope, with a magnifier of ten times its diameter. I then discovered, by means of the absence of the bubbles of gas, another phenomenon besides that of the centrifugal movement of the solution, which was the only one I had perceived previous to that. I saw all around the small fragment of soda whirlpools, indicated by the alternate movements of attraction and repulsion of the argillous particles, which thus moved in short curves, apparently circular, and whose diameter did not exceed three-tenths of a millimeter. This was the same phenomenon, but about three times smaller, as that which camphor on the surface of water had presented to me (15); and likewise the progressive movements which an alkali presented at the surface of water, when it is held in suspension by pieces of cork, are due exactly to the same causes as those which produce the movements of camphor: namely, the repulsion exercised by the bodies which are dissolved on the aqueous solution, and the alternate actions of attraction and repulsion exercised by this same body on the water which surrounds it. We cannot doubt but that the feeble movements which certain acids and salts ▾ present, when held in suspension on the surface of water, are due to the same causes. I may say the same of the movements presented in the same circumstances by small fragments of aloes succotrine, opium, &c. In all cases, it is the action of the solution which gives birth to these electrical phenomena, and which manifest themselves by attractions and repulsions on the surrounding liquid, and the effect of which reaction puts in movement these soluble bodies where they are floating.

22. The vigorous movement of progression which potassium pre

sents when burning on the surface of water, is a phenomenon due, like the preceding ones, to an electric action, and not to the rapid disengagement of hydrogen gas, as we have already admitted. To be assured of this fact, it is not necessary to have pure potassium to submit here to observation, its combustion and its effects on water are too rapid; it is necessary to observe it alloyed with antimony, made after the method described by Serullas. This alloy, reduced into small fragments, moves with rapidity, whether it is floating on the surface of the water, or whether it is entirely immersed in this liquid. The potassium, thus alloyed with antimony, does not decompose the water with great rapidity, as pure potassium does; in this case, the action is not very brisk, and endures sufficiently long to enable us to study its effects. I have placed under the microscope, and with the feeble magnifying power of ten times the diameter, a small fragment of the alloy of potassium and antimony, placed on a plate of glass, at the side of a small sheet of water which held argillous particles in suspension. At the moment of contact of this fragment of alloy with the water, there was produced a disengagement of bubbles of hydrogen gas, directed like a rapid jet towards the interior of the small sheet of water. The direction of this jet was always the same, though the fragment of alloy was agitated and returned in different directions by the effect of recoil or of reaction. On arriving at five or six millimetres distance from the fragment of alloy, the jet of hydrogen gas disappeared; because the small bubbles which composed it issued from the water and spread themselves in the air. But the jet itself was not discontinued at any time, it went farther on, formed only then by the, water, rendered visible by means of the argillous particles which it held in suspension. Soon, however, this jet became divided into two parts, turning towards the right and left, and I saw the argillous particles return, on accomplishing a revolution, towards the fragment of alloy, in order to enter anew into the jet, which was thus evidently at the time composed of water and bubbles of hydrogen gas. But the production of this gas soon ceased to be either so rapid or so abundant, the bubbles were disengaged slowly, and no longer quitted the sides of the small fragment of alloy. However, this jet continued to be evolved, though ouly indicated by the movement of the argillous particles; which afterwards returned, by parting towards the right and left near the fragment of alloy, thus forming two eddies or whirlpools. There was here, then, evidently alternate actions of repulsion and attraction of the water, like that which was observed from the contact of oily or resinous bodies with water; and there can be no doubt, but that these actions are the same, and that they are electrical. The jet here in question is the result of repulsion, which, being very active at first, acts at the same time on the water, or rather on the solution of potash in the water, and on the bubbles of hydrogen gas, which are abundantly disengaged. This gas being afterwards only slowly disengaged, and the repulsion becoming less active, it no longer acts on the water, or on the solution of potash