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of science; but his energies had washed asbestos. Thus then was not slumbered; he had been enga- every source of fallacy connected: ged in experiments of the most ar. with the apparatus removed; but duous and complicated description; still the same production of saline and in presenting their results, he matter appeared. What could be unfolded the mysteries of Voltaic its origin? He repeated the expe. action. This grand display of sci. riments in cups of gold, and exam. entific light burst upon Europe like ined the purity of his water by a meteor, throwing its radiance in. evaporation in vessels of silver. to the darkest recesses, and open At length he succeeded in recog ing to the view of the philosopher nising the source of this matter; it new and unexpected regions. The was of foreign origin, partly deri. memoir in which these discoveries ved from the contents of the water, were announced constituted the and partly from new combinations Bakerian lecture; and was read of gaseous matter. This was cu. before the Royal Society on the rious, but, after all, a discovery in 20th November, 1806. We shall itself of insignificant value, when endeavour to offer as popular a re. compared with those which imme. view of its contents as the abstruse diately flowed from it. The acid nature of the subject will allow. It and alkaline matter then produced, had been observed, during some of it has been already stated, collectthe earliest chemical experiments ed in the water round opposite poles, with the Voltaic pile, that when the the former always appearing at the purest water was submitted to the positively electrified, the latter at action of a current of electricity, the negatively electrified surface, acid and alkaline matter were se.
Was this a universal law ? was parated at the opposite electrified necessary to decide this question surfaces. A fact so extraordinary by more extended inquiries. The necessarily excited various con. first series of experiments which he jectures; and many believed that instituted for this purpose, embra, the bodies were actually generated ced the decomposition of solid bus by the action of the pile. Davy, dies, insoluble, or difficultly soluble however, soon negatived so unphi. in water. From the effects of the losophical a conclusion, and show. electrical agency on glass, already ed that they merely arose from the mentioned, he very reasonably exdecomposition of the materials em. pected that various earthy com. ployed: he found, for instance, that pounds mnight thus undergo changes the glass vessel, at its point of con under similar circumstances : and tact with the wire, was corroded; his conclusion was just. From sul. a fact which sufficiently explained phate of lime he obtained sulphuric the source of the alkali; while the acid in the positive, and a solution animal or vegetable materials, em. of lime in the negative cup. These ployed as conductors, might be rea. experiments were extended to a dily supposed to furnish the acid. great variety of other compounds, He accordingly proceeded to work such as sulphate of strontia, fluate with cups of agate; and, at the of lime, sulphate of baryta, &c., suggestion of Dr. Wollaston, who and with parallel results. Having again acted as a Mentor, he form. thus far established the general ed the connecting parts of well. law, he proceeded to inquire into
the mode and circumstances under ing positive, others negative.-
attraction invariably subsists be.' tion; a violent effervescence com. tween oxygen and the positive pole, menced at the upper or positive and inflammable matter and the surface, while at the lower or ne. negative pole ; thus, in the decom. gative, instead of any liberation of position of water, its oxygen was electric matter, which must have constantly transferred to the for. happened had hydrogen been pre. mer, and its hydrogen to the latter. sent, small globules having the apFurnished with such data, Davy pearance of quicksilver were dis. proceeded to submit a fixed alkali engaged, some of which were no to the most intense action of the sooner formed than they burnt with Galvanic pile; believing that if it explosion and bright flame. The contained any hydrogen, or other gaseous matter developed at the inflammable basis, it would be se. positive pole, was soon identified parated at its negative extremity, as oxygen; but to collect the me. and if any oxygen, that it would tallic matter at the opposite exappear at the opposite end. His tremity, in a sufficient quantity for first attempts were made on solu. a satisfactory examination, was not tions of the alkalies; but, notwith so easy; for such was its attrac. standing the intensity of the elec- tion for oxygen, that it speedily re. tric action, the water alone was de verted to the state of alkali by re. composed, oxygen and hydrogen combining with it. After various being disengaged with violent ef. trials, Davy found that recently. fervescence, and transferred to distilled naphtha presented a me. their respective poles. The pre. dium in which it might be preserved, sence of water thus appearing to by covering the metal with a thin prevent the desired decomposition, transparent film of Auid, which de. potass, in a state of igneous fusion, fended it from the action of the air, was submitted to experiment; and at the same time allowed an when it was immediately evident accurate examination of its physithat combustible matter of some cal qualities. Thus provided, he kind, burning with a vivid light, was proceeded to investigate the progiven off at the negative wire. Af. perties of the body; giving to it ter various trials, during the pro. the name of potassium, and which gress of which the numerous diffi. may be described as follows. It culties which successively arose is a white metal, instantly tarnishwere as immediately combated by ing by exposure to air; at the temingenious manipulation, a small perature of 70° Fahrenheit, it expiece of potass, sufficiently mois. ists in small globules, which pos. tened by the breath to impart to it sess the metallic lustre, opacity, a conducting power, was placed on and general appearance of mercu. an insulated disc of platina, and ry ; so that when a globule of mer. connected with the negative side cury is placed near one of the po. of the battery in a state of intense tassium, the eye cannot discover activity, and a platina wire commu any difference between them. At nicating with the positive side, was this temperature, however, the me. at the same instant brought into tal is only imperfectly fluid; but contact with the upper surface of when gradually heated, it becomes the alkali. The potass began to more and more fluid ; and at 1500, fuse at both its points of electriza. its fluidity is so perfect, that seve.
ral globules may easily be made to in other words, a body composed run into one. By reducing its tem. of oxygen, and a metal of the most perature, it becoines at 500 a soft singular description, so light as to and malleable solid, which has the swim upon water, and so inflam. lustre of polished silver; it is soft mable as to catch fire by contact enough, indeed, to be moulded like with ice! vax. At about the freezing point From these observations it will of water, it becomes hard and brit. be immediately perceived, that the tle, and exhibits when broken a decomposition of the fixed alkali crystallized texture of perfect placed in the hands of the experi. whiteness and high metallic splen- mentalist a new instrument of an. dour. It is also a perfect conduct. alysis, scarcely less energetic or or of both electricity and heat. of less universal application than Thus far, then, it fulfils every con. the power from which the discove. dition of a metal; but we have now ry emanated. So strong is the af. to mention a quality which has been finity of potassium for oxygen, that as invariably associated with the it discovers and decomposes the idea of a metal as lustre ; and its small quantities of water contained absence, therefore, in potassium, in alcohol and ether. But, perhaps, has given rise to a question whe. the most beautiful illustration of its ther, after all, it can with proprie. deoxidizing power, is shown in its ty be classed under this denomina- action on fixed air, or carbonic tion ;-we allude to great specific acid; when heated in contact with gravity. Instead of possessing that that gas, it catches fire, and by ponderosity which we should have uniting with its oxygen becomes expected in a body otherwise me. potass, while the liberated carbon tallic, it is so light as to swim, not is deposited in the form of charonly upon the surface of water, but coal. upon that of naphtha, by far the Upon submitting soda to the elec. lightest fluid in nature. Thrown tric battery, under circumstances upon water, it instantly decomposes such as those we have already de. the fluid, and an explosion is pro- scribed, a bright metal was obtain. duced with a vehement flame; an ed similar in its general character experiment which is rendered more to potassium, but possessing dis. striking if, for water, ice be substi. tinctive peculiarities which it is tuted. In this latter case it in. not necessary to detail : to this stantly burns with a bright flame, substance Davy gave the name of and a deep hole is made in the ice, sodium. filled with a fluid, which is found to These important discoveries were be a solution of potass. It is followed up by an investigation in. scarcely necessary to state that this to the nature of the earths; and phenomenon depends upon the ve. the results were communicated in ry powerful affinity which the me. a paper, read before the Royal Sotal possesses for oxygen, enabling ciety on the 30th of June in the it even to separate it from its most same year. It appears that this subtle combinations. The evidence investigation required still more re. afforded of the nature of the fixed fined and complicated processes alkali, potass, is thus rendered com. than those which had succeeded plete. It is a metallic oxide, or, with the fixed alkalies, owing to
the infusible nature of the earths ; H. Davy charged himself with the the strong affinity of their bases for inquiry; and presented its results oxygen made it unavailing to act in a paper, which was read before upon them in solution in water; the society on the 22d of January, and the only methods that proved 1824, and which was continued in successful, were those of operating another communication dated 17th upon them by electricity in some of June, 18:24, and concluded in a of the combinations, or of combin. third, read 9th of June, 1825. ing them at the moment of their We shall endeavour briefly to decomposition by electricity, in state the principal facts elicited metallic alloys, so as to obtain evi. by this inquiry. We have already dences of their nature and proper. stated, that Davy had advanced the ties. It is impossible to follow the hypothesis, that chemical and elec., philosopher through all the intri. trical changes were identical, or cate paths of this investigation : dependant upon the same property suffice it to say, that, although he of matter; and that he had shown was unable to produce the metallic that chemical attractions may be bases of the earths in the same un. exalted, modified, or destroyed, by equivocal form as he produced changes in the electrical states of those of the alkalies, he furnished bodies; that substances will only sufficient evidence of their being combine when they are in differ. metallic oxides.
ent electrical states ; and that, by Sir Humphrey Davy's Bakerian bringing a body, naturally positive, Lecture of 1808, entitled, "An Ac. artificially into a negative state, its count of some new Analytical Re. usual powers of combination are searches on the Nature of certain altogether destroyed : it was, in Bodies, particularly the Alkalies, short, by an application of this ve. Phosphorus, Sulphur, Carbona. ry principle that he decomposed ceous Matter, and the Acids hith. the alkalies; and it was from the erto undecomposed; with some same energetic instrumentality that general Observations on CHEMICAL he now sought a remedy for the ra. THEORY,” abounds in elaborate ex. pid corrosion of copper sheathing. periments with the Voltaic
When a piece of polished copper is tus, made with the hope of extend. suffered to remain in sea-water, the ing our knowledge of the principles first effects are, a yellow tarnish of bodies, by the new powers and upon the surface, and a cloudiness methods arising from the applica. in the water, which take place in tion of electricity.
two or three hours: the hue of the Shortly after the close of the war, cloudiness is at first white, and it the commissioners of the navy, gradually becomes green. In less fully impressed with the evil ari. than a day a bluish-green precipitate sing from the destructive influence appears in the bottom of the vessel, of sea-water upon the copper which constantly accumulates; this sheathing of his majesty's ships of green matter appears principally war, applied to the council of the to consist of an insoluble compound Royal Society, in the hope that some of copper (a sub-muriate) and hy. plan might be suggested for arrest. drate of magnesia. Reasoning up. ing, if not for preventing, the de. on these phenomena, Davy arrived cay of so expensive an article. Sir at the conclusion that copper could