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sition might be effected according to the same law, and by a similar mode of operation. This hint was thrown out in the same paper. I have, however, found, that the results of all experiments of this kind, are modified by the strength of the metallic solutions. But the fact that all the metals (which constitute about one-half of the known simple bodies) being determined at the negative polar terminal, when liberated from their combinations with other bodies by electric currents, is strongly in favour of the views I have taken on this topic.
407. The term electric current has become so exceedingly familiar and convenient, that it is employed without hesitancy by almost every writer on the subject, though the universal taciturnity on the mode of propagation, leaves a sad blank in every hypothesis hitherto made public.* The principles I have already embodied in this memoir, although perfectly explanatory of the preliminary conditions essential to the production of a voltaic electric current, as far as electro-distribution and polarization are concerned, would leave the associated group of metals and water in a perfect electrostatical repose. But it bas been shown (402) that such an equilibrium is not stable with such an arrangement of these materials, and that the first consequence is a decomposition of a portion of the water, which, once accomplished, motion is again produced in the electric fluid; and, so long as any part of the water is suffering a change from its constituents being torn asunder by the assailing electric forces, no stable equilibrium can be maintained, and the electric fluid, as a matter of course, is kept in a continual state of commotion. Hence it is, that, although the decomposition itself is the primary effect of the combined electric forces of the metals and the water, it is not only the first step in the production of a current, but absolutely essential to its existence and propagation.
408. Volta, whose theory of the pile was similar to that I have explained, with the exception of the view I have taken respecting the propagation of the current (407), considered that the water was a mere conductor between the metals; but it is easily demonstrated that no electric current, nor electro-circulation, can possibly be produced independently of motion in some of the other elements employed in the arrangement. I have shown, some years ago, in the Phil. Mag., and I think in the Annals also, that, in the production of thermo-electric currents, where the calorific matter is the motiveagent, and in the production of magnetic-electric currents, where the magnetic matter is the motive agent, a disturbance of those agents is an essential preliminary to the existence of these currents, and an indispensable circumstance in their propagation. And it is equally demonstrable that, with whatever degree of force the electric fluid might be disposed to expand, and move in any one direction more than
In a small work on Electro-gilding, &c, lately published, and occawionally in other places, I have attempted to show by what means voltaic electric currents are propagated.
another, it would speedily equilibrate amongst such bodies as would not yield to its powers, and again assume a determinate statical repose. Hence, under such circumstances, no propagation of acurrent could possibly take place.
409. By some writers on this subject, the existence, even of a current has been questioned; but these are few in number, and those few have advanced nothing to the contrary but mere sceptical surmise ; probably, more with a view of appearing singular, than from any train of reasoning they have bestowed on the subject. That a current does exist no experienced man can doubt; but, uutortunately for their readers, few writers are experienced men. We have some beautiful analogies in mechanical and voltaic electricity, and some peculiar phenomena exhibited in the latter branch, from whose direct inferences there seems to be no appeal.
410. If a series of pointed metallic wires were to be arranged, as in Fig. 9, and one of the extreme points placed near to the conductor of
an electric machine in good action, a luminous star would tip every point in the series that is directed towards the prime conductor; and those points of the wires which are presented in the opposite direction, or from the conductor, would exhibit a beautiful brush of electrical light. Now, since it is admitted that the star and brush are, respectively, indicative of a receiving and a delivering extremity in each wire, it follows, that an electric current is passing through the whole series, and also through the interposed plates of air. Moreover, it must be borne in mind, that a delivering surface must be positive to that which receives the electric fluid from it. Hence, we are led to understand that each wire and each plate of air is electro-polar, and that this polarity is essential to the existence of the current; and vice versa, the current is a consequence of the polarized state of the wires and interposed plates of air.
411. The counterpart of the last described phenomena, is beautifully displayed in voltaic electricity. Let a series of metallic wires be arranged in a glass tube holding acidulated water, as represented in Fig. 10,
and the two outer ends of the extreme wires in connection with the two poles of a voltaic battery. Every wire in the series becomes electro-polar, liberating hydrogen at those extremities which point towards the positive pole, and oxygen at those which point in the opposite direction. If the tube contain a blue neutral solution of
acid and alkaline matter, and the wires be platinum or gold, the well known characteristic red and green colours will shortly appear. Now since there is an electric current produced in the former case, (410) the analogy is sufficiently striking and complete to inser that a current is also in existence in the latter : indeed no other satisfactory conclusion can be arrived at, and since a series of wires similarly arranged within the liquid in a battery, display phenomena as decidedly as a series without it, in the glass tube, for instance, there can be no reason to doubt the existence of a current throughout the whole system.
412. The direct effects of an electric current are strikingly manifested by the different appearances of charcoal points, after deflagration; the delivering piece being pointed, and the receiving piece being rendered concave.
413. It is well known that I have, for many years, advocated the non-identity of the electric fluid, and the calorific Auid (First Memmoir, 28);* and I know of no fact that supports these views more completely than that which I discovered in the autumn of 1838, with a battery of one hundred and sixty pairs of copper and zinc.f In that remarkable phenomenon, I can see no other mode of explanation than that which I have already given in my letter to Professor Silliman : I viz., that the electric Auid, which is an exceedingly active agent, was enabled by its volant powers, to spring from wire to wire, through the intermediate stratum of air; whilst the comparatively sluggish calorific fluid, being unable to traverse the aerial space with the same degree of velocity, was thrust out of the electric path, and forcibly compressed into the remotest extremity of the positive wire, and entirely exterior to the electric circuit.
414. But the same phenomenon, which is so happily applicable to the support of those views (413), is also demonstrative of the existence of a current; and perfectly conclusive of the direction in which it flows through the conducting wires, for reasons already given. || Moreover, the direction of the current in a voltaic circuit, is demonstrable by its magnetic effects, from the analogies which they exhibit with those mauifested by the discharge of a Leyden jar. Since, therefore, the existence of electric currents in a voltaic circuit, are so strikingly manifested by the display of so many indubitable facts, those currents necessarily emanate from a primary cause; which, as I have already stated, (408), is not to be found in any group of unyielding and unalterable bodies; and, as the metals suffer no alteration prior to the decomposition of the water, this latter is the primary effect of the electro-polarization, and is essential to the production and propagation of the current.
(To be continued.) • Annals of Electricity, &c., vol. ii, p. 416.
† The particulars of this battery, and of the experiments in question, will be found in the Annals of Electricity. vol. v, p. 365: also in Silliman's American Journal. In one of my lectures, at this Institution, in the present month, May, I produced the same phenomenon by fifty pairs of Groves' battery.
Ibid. l! Ibid.
Experiments on Bichlorure of Sulphur and certain Carbures of
Hydrogen, made in the laboratory of Jefferson College (Louisiana). By Prof. F. CHEVET.*
A CURRENT of bicarbure of hydrogen being brought to bear on some bichlorure of sulphur, under the influence of the solar rays, the gas was absorbed in considerable quantities with a great throwing off of heat. The liquid, at first of a very deep pomegranate red, gradually became orange coloured, then of a yellow orange colour. The light refracted by the ball containing the bichlorure, assumed the finest violet hue, like that produced by vapour of iodine. This colour lasted a very long time.
Among the vapours thrown off at first, the writer thought he remarked chlorohydric ether and sulphohydric ether. These vapours made the water through which they passed milky, but this effect soon ceased. Towards the end of the operation, the gases evolved burned with a very fuliginous flame, like bicarbure of hydrogen, pure; however they by no means had the same smell. There appearing to be no absorption, the liquid was gradually heated to bring about absorption, by producing an atmosphere of vapours; suddenly the yellow liquid assumed a raspberry red colour, but no marked absorption was effected. Its bulk was very viscous, like a thick syrup; its smell was penetrating and very enduring, similar to that of blackberries or raspberries; its flavour was at first sweet, then very pungent.
The next day, a deposit was found of a number of small needleshaped crystals of a deep brown.
Neither water, alcohol, nor ether, appears to dissolve these crytals to any decided amount; however alcohol discolours them, whilst it colours itself and leaves a drop of red liquid by evaporation. Water casts off from the alcoholic solution a white powdery deposit, and leaves a red drop at the bottom of the vessel. Nitric acid, cold, appears not to act, but warm, it dissolves the crystals and gives a yellow sediment of sulphur.
The crystals, having been several times washed with alcohol, assumed a light chocolate colour; after being strained through pieces of blotting paper they were discoloured, leaving on the paper a very volatile oil which rapidly disappeared, but there remained a red stain on the paper, which shows that the volatile oil is distinct from that species of colouring matter. The crystals strained through paper, were placed in the pneumatic vacuum in the presence of sul-phuric acid, and moist fragments of potash; the surface of the acid became of a decidedly roseate hue, and bespriukled with small oily drops ; the potash had absorbed some of the chlorine. These crystals were then pretty white, and burned in a very lively manner, bubbling up and emitting a flame which betokened the presence both of sulphur and of a resinous matter. Sulphuric acid appears
• Silliman's American Journal of Science.
powerless on these crystals, unless it be that it discolours them. Another part of the crystals having undergone a potash solution, gave a solid and very gluey deposit of a dirty yellow; the solution became yellowish; the sides of the vessel in which the operation was performed, became very greasy; the deposits, as well as the potash solution, had a very strong and decided smell of cucumber.
The red liquor, in the midst of which was the mass of crystals, slightly smoked in the open air, though its point of ebullition was pretty higb; its density is greater than that of sulphuric acid, but a part floats even above the water, which betokens a complex liquid; it is insoluble in water and in ether, but rather soluble in alcohol; however, the alcoholic solution having evaporated, appears to leave the liquor untouched; water brings about a powdery deposit of a currant red.
This liquid, on distillation, gives a yellowish oil of a flavour acrid, pungent, and very enduring; it reddens the blue
doubtless by free chlorohydric acid.
The writer further made bichlorure of sulphur, prepared cold, react on two other carbures of hydrogen, oil of naphtha, and essence of turpentine, both as highly rectified as possible. With the oil of naphtha, the action is lively, and accompanied by a marked ebullition; the temperature rises rapidly, and a considerable quantity of chlorohydric acid is thrown off. A black deposit of a very glutinous nature was obtained; the liquid assumed a very brown red colour. The whole, being distilled, gave a yellowish liquid, which, being washed with water, furnished a yellowish and glutinous mass, floating on the liquid; it was sulphur impregnated with a very volatile oil, rapidly disappearing from the paper used for straining, and without any sediment. This mass undergoing a warm preparation with alcohol, considerably diminished in bulk, and, after cooling, oily drops gathered on the surface. Ether dissolves this species of oil better than alcohol ; what remained undissolved by the ether, still betokened, on being burned, the presence of a resinous matter; it was then subjected to the influence of boiling nitric acid, which left a globule of sulphur. The washings of the distilled liquid contained much chlorohydric acid, and also some sulphuric acid.
The deposit left in the cucurbite became blacker and more plentiful; it burned like resin, and did not appear to contain sulphur; it is soluble in nitric acid, warm, and after a suitable evaporation, it deposits very long needle-shaped crystals of perfect whiteness; these crystals are of a slightly bitter favour, and have no feature of acidity.
With the essence of turpentine, the reaction is extremely tumultuous. The vessel in which the operation was made was sunk in cold water, and yet the matter boiled up considerably; the mass became very viscous, but it remained homogeneous. Distillation was performed; a great quantity of chlorohydric vapours were thrown off by the draught tube ; a pomegranate-red liquid condensed in the recipient; this liquid exhaled a stinking smell, pretty similar to that