Sir Humphry. This eminent philosopher was born on the 17th of December 1778, in the small town of Penzance, in Cornwall, of very respectable parents, in the humbler walks of life. In that place he received the elements of his education, until 1793, when he was removed to the grammar-school of Truro, then under the direction of the Rev. Dr Cardeew. There is scarcely anything worthy of record in the early years of Davy, except the facility with which he appears to have gleaned the substance of any book that happened to engage his attention, and his early predilection for poetry.

No biography of Davy should omit the disinterested friendship of Mr Tonkin, a respectable medical practitioner of Penzance. This amiable man had adopted the mother of Davy and her sisters, under circumstances of deep distress; and his kindness was extended to all her children, particularly Humphry, whose intended professional career was probably influenced by that of his friend and patron.

In 1794 Davy lost his father, and his mother found herself under the necessity of becoming a milliner in Penzance, whilst young Davy was, in 1795, apprenticed to Mr Borlase, then practising as a surgeon-aphothecary, but who afterwards became a physician in that place.

While yet very young, our philosopher had exhibited traces of an ardent, inquisitive mind, an inclination for devising experiments, and for examining the productions of nature. On entering the service of Mr Borlase, his attention was turned to chemical investigations, which he pursued with a characteristic enthusiasm, to the neglect of the humbler art of compounding medicines. His chief laboratory at that time was the garret of his friend Mr Tonkin, who was occasionally alarmed and annoyed by unexpected explosions. His defective apparatus was supplied by the fertile resources of his own ingenuity. It was during this period that he attempted to investigate the nature of the air contained in the vesicles of sea-weed; and his ingenuity in supplying his want of more perfect instruments is well illustrated in the facility with which he contrived to supply the place of an air-pump, by an old French injecting syringe, which accident put into his hands. With this he made several experiments, and actually employed it as an air-pump, in his first original paper on the Nature of Heat and Light.

Davy was not of a temperament or cast of mind to remain long in obscurity. The panting after scientific renown had early taken possession of his soul; and while still the apothecary's apprentice, and regarding medicine as his future means of support, he felt aspirations after distinction in the paths of philosophical discovery; but he was in some degree indebted for an earlier emergence from the obscurity of his native place, to the accidental notice of Mr Davies Giddy Gilbert. The attention of that gentleman had been arrested by the strange contortions of countenance of an ungainly boy, whom he observed hanging over the hatch-gate of Mr Borlase's house; and on being informed that the boy was "a son of Davy the carver, and very fond of making chemical experiments," he sought the acquaintance of young Davy, and was ever afterwards his steady friend.

Another accidental acquaintance was not without its influence on the fortunes of Davy. The late Mr Gregory Watt, long an invalid, had been recommended by his physicians to try the mild air of Cornwall, and took up his lodgings in the house of Mrs Davy. Their first intercourse was not cordial. Watt was taciturn and reserved; and young Davy, with that want of tact which is not uncommon at his age, instead of endeavouring to recommend himself by showing his knowledge of any branch of experimental or natural philosophy which he had studied, sought to make an impression on the valetudinarian inmate of his mother's house by crude and flippant metaphysical speculations. Watt was disgusted, and retired within himself, until an incidental remark of Davy on the imperfection of the French theory of combustion and calcination arrested the attention of the former. They then began to discuss questions congenial to the minds of both, and soon became attached friends.

It was through these two gentlemen that the subject of our memoir was introduced to Dr Beddoes, who had visited Cornwall on a geological tour, in company with his friend and philosophical opponent Professor Hallstone of Cambridge. The abilities of Davy were favourably shown during the friendly contentions of these rival geologists; and their judgment being advantageously impressed by the encomiums of Gilbert and Watt, Davy was soon afterwards engaged by Dr Beddoes to superintend a pneumatic medical institution, which that able but eccentric man had just then established at Bristol, for the treatment of diseases.

After some negotiation, Davy, much to his own satisfaction, received the appointment of superintendent, and repaired to Bristol in 1798, before he had completed his twentieth year. Mr Borlase readily gave up Davy's indenture; but this removal was a severe disappointment to Mr Tonkin, who had placed his fondest hopes on seeing his young friend settled as a practitioner in Penzance.

Davy was now placed in a sphere where his genius could expand; he associated with men engaged in similar pursuits; he was provided with suitable apparatus; and he speedily entered upon that brilliant career of discovery which has rendered his name illustrious among philosophers. It was not his original intention to abandon the study of medicine; but after his engagement with Dr Beddoes had terminated, he had intended to prosecute his medical studies at Edinburgh; a plan which he was induced to abandon by the all-engrossing interest of his chemical discoveries.

Soon after his removal to Bristol, his speculations on Heat, Light, and Respiration, appeared in Beddoes's "West-Country Contributions." In that essay, written before he left Cornwall, he endeavoured to prove the immateriality of heat, by showing its generation from the friction of two pieces of ice under the exhausted receiver; but his reasoning on this point was inconclusive, and his mode of insulating the ice very imperfect; whilst it is well known that heat will radiate through the most perfect vacuum. His speculations on Light and Respiration are extravagant, and savour little of the spirit of philosophical induction. It was unfortunate for Davy that he had not a more judicious adviser than Beddoes, a man singularly devoid of philosophical caution, and easily led astray by the loosest analogies.

Davy's first scientific discovery was the detection of siliceous earth in the epidermis of the cane, reeds, and grasses. Though the chain of induction be simple, yet the steps give a favourable specimen of his method of investigating phenomena. A child had accidentally discovered, that on rubbing together two pieces of bonnet-cane, a faint light was emitted; on examining the fact, he found, that on striking them together, vivid sparks were produced, like those emitted by the collision of flint and steel. On stripping off the epidermis the luminous property was lost, and analysis showed that the epidermis contained silex. The shining appearance of the stems of reeds, corn, and grasses, induced him to examine them also, and he found that they all yielded silex, even in larger quantity than the cane.

About the same period he made his first gaseous discovery, the respirability of nitrous oxide. The first intimation of its intoxicating qualities is given in a letter to his friend Mr Gilbert, dated April 16, 1799. Soon after, he examined its proprieties more accurately, administered it to various individuals, and published an account of his discoveries in a volume entitled *Researches Chemical and Philosophical, chiefly concerning Nitrous Oxide and its Respiration*. This essay breathes a very different spirit from his first. It exhibits good models of cautious induction from ingeniously contrived experiments, and shows a happy talent for analyzing the different circumstances which influence the chemical changes observed.

Fortunately for Mr Davy, while the impression from this publication was still fresh on the public mind, the establishment of the Royal Institution in London, under the auspices of Count Rumford, had taken place; and a lecturer of talent was wanting to fill the chemical chair. Dr Hope of Edinburgh has the merit of thus early discovering the high talents of Davy, and of introducing him to the notice of the count; and he was, in the beginning of 1801, chosen lecturer to the institution, and director of the laboratory.

It has been said, that on his first appearance in London, his ungainly exterior had prejudiced Rumford and some other directors against him; but when he began to lecture, he won the approbation of all. His lectures became a fashionable lounge; his ingenuity and happy facility of illustration gained him a high reputation; his company was courted by the choicest society of the metropolis; and soon his presence was regarded as an indispensable requisite in the brilliant soirees of the gay and fashionable world. Adulation paid to talent became fashionable; and at the early age of twenty-two Davy had triumphed over considerable personal defects, and found himself the idol of an admiring capital.

Those who had enjoyed an opportunity of observing him at Bristol, had remarked the simplicity of his mind and manner at that period; and they had noticed his talent for discussing difficult questions, even where his information was exceedingly defective. That the extravagant adulation of the metropolis, so soon after his appearance there, should have been injurious to his native simplicity of manner, is far less surprising, than that it did not entirely destroy that ardour in research which conducted him to fame.

Davy's style of lecturing was well adapted to command the attention of his audience; it was animated, clear, and impressive, notwithstanding the naturally unharmonious tones of his voice; whilst the ingenuity of his happily devised experiments, and the neatness of their execution, were calculated to fix the attention of his hearers. How much these circumstances are calculated to affect the usefulness and popularity of a teacher, is well illustrated by the different impression made on nearly the same audience by the no less original but more profound lectures of Dr Thomas Young, which were discontinued by the committee of the Royal Institution two years after the appearance of Davy.

The young chemist was fortunate in the time of his commencing his metropolitan career. Experimental chemistry was beginning to be the fashion of the day, and it was a very general topic of conversation among the upper circles. Voltaic electricity had just been found to possess the most extraordinary powers of effecting decompositions of chemical compounds; and innumerable experimental chemists, aware of the field of discovery which this powerful instrument promised to open to these researches, were most anxious to possess a powerful galvanic battery. The liberality of the committee of the Royal Institution supplied what few private individuals could afford; and early in his first course as professor of chemistry, Davy was put in possession of a battery of four hundred five-inch plates, and one of forty plates a foot in diameter. With these his early and most brilliant investigations were conducted; and their liberality and his ingenuity were rewarded by the discovery of the metallic bases of the alkalies.

The first communication of Davy to the Royal Society was "an account of some galvanic combinations formed by an arrangement of single metallic plates and fluids," which was read in June 1801. This paper is the first of that series of electro-chemical investigations which have immortalized his name. In all hitherto constructed piles, the series had consisted of not less than two metals, or of one plate of metal, another of charcoal, and some interposed fluid. He showed in this paper, that the usual galvanic phenomena might be energetically exhibited by a single metallic plate and two strata of different fluids, or that a battery might be constructed of one metal and two fluids, provided one of the fluids was capable of causing oxidation on one of the surfaces of the metal. Between this communication and his next paper on galvanic phenomena five years elapsed; a period during which many interesting discoveries were made by other philosophers; but Davy had not been idle. In 1802 he was appointed professor to the board of agriculture; and, in addition to the duties of his situation in the Royal Institution, to which that of joint editor of the Journal had been added, he gave a course of lectures on the connection between agriculture and chemistry, which was annually continued for ten successive years. In 1803 he was admitted a member of the Royal Society, of which he became first the secretary, and ultimately the president; and he continued to enrich the transactions with numerous memoirs on different branches of experimental philosophy for twenty-five years. Indeed his most valuable productions are contained in the Philosophical Transactions; and it is on these detached papers that his claims to celebrity almost entirely rest. Of his other publications, the Elements of Chemical Philosophy was a signal failure, and only the first volume ever saw the light. His Elements of Agricultural Chemistry had some popularity, though they have scarcely added any thing to our previous stock of knowledge; but there is scarcely one of his communications to the Royal Society which does not announce some new and important fact, or does not elucidate some general principle of experimental philosophy.

He had undertaken to deliver some lectures on the principles of the art of tanning, and had been furnished with the means of obtaining practical and experimental knowledge on the subject. In the course of his preparation for these lectures he discovered some new facts, which were first noticed in the journals of the institution, and afterwards embodied in an elaborate communication to the Royal Society, entitled *An account of some experiments and observations on the constituent parts of certain astrigent vegetables, and their operation in tanning*, read in February 1803.

In 1805 he read two papers to the Royal Society. The first was *An account of some analytic experiments* on the Wavelite, which he affirmed to consist of alumine and water. In this analysis he overlooked the presence of fluorate of alumine, which was detected in it by the Rev. William Gregor; and still more unaccountably did both the British chemists fail to detect in the mineral phosphate of alumine, which was found afterwards by Berzelius to constitute one third of it. The second paper of Davy, *On the method of analysing stones containing a fixed alkali, by boracic acid*, is really an important addition to analytic chemistry. His method is founded on the strong affinity of that acid for different earths at the point of incandescence, and on the ease with which these borates are decomposed by the mineral acids. We now approach the period of Davy's great discoveries.

The power of the pile to effect decompositions was shown in 1800 by Nicholson and Carlisle, and immediately extended by Cruickshank. The appearance of alkalies and acids at opposite poles of the battery had been noticed by different philosophers, but it was reserved for Davy to connect these discoveries by one general law, and to illustrate his theory of Voltaic action by some most happily devised experiments, in the Bakerian lecture, read to the Royal Society in November 1806. It will be sufficient to state, that he satisfactorily showed that the liberation of acid at the positive pole, and of alkali at the negative pole, proceeded entirely either from the decomposition of the vessels used in the experiment, the impurity of the water subjected to analysis, or from the elements of the atmosphere uniting with the hydrogen or oxygen of the water to form ammonia or nitric acid. By a series of very elegantly conducted experiments, he showed that in all Voltaic decompositions the tendency of the electric action was to collect the acid of the compound at the positive wire, and its bases, whether alkaline, earthy, or metallic, at the other pole. He proved that such transfers were not confined to the immediate neighbourhood of the poles, but extended through the whole galvanic circuit which connected them; and that even an acid might be conveyed from one wire to the other, through an alkaline, earthy, or metallic solution, without entering into union with it, provided the substance transferred did not form an insoluble compound with the interposed solution. When it did form an insoluble compound, it was withdrawn from the Voltaic action, and consequently its transference was stopped. After examining a great number of such phenomena, he generalized the results by stating, that hydrogen, the alkalis, earths, metals, and certain oxides, are attracted by negatively electrified, and repelled by positively electrified metallic surfaces; that oxygen and acids are attracted by positively, and repelled by negatively electrified metallic surfaces.

After these practical elucidations, Davy proceeded to investigate the law of electro-chemical action. In repeating and extending the researches of Bennet, Cavallo, and Volta, on the electricity evolved by the contact of bodies, Davy showed, that substances capable of chemical union exhibited unequivocal symptoms of opposite electrical states; that the mutual chemical attraction of the elements of a compound are subverted by inducing an electrical state opposite to that natural to them; while their chemical union is promoted by increasing their natural electric energies. Hence he drew the inferences, that electro-chemical combinations and decompositions are referrible to the law of electric attractions and repulsions, and that both "chemical and electrical attractions are produced by the same cause, acting in the one case on the particles, in the other on the masses."

The whole of this beautiful memoir is a happy example of most admirably devised experiments, legitimate deductions, or ingenious inferences. What is fully established, is carefully discriminated from what rests on probable conjecture; and it raised the reputation of Davy to the highest pitch. It procured for him not only the willing homage of his own countrymen, but it was crowned by the French Institute with the medal of three thousand francs, founded by the first consul for the encouragement of discoveries in galvanism; a proud triumph of scientific reputation over national jealousy, and the implacable acrimony of our then national hostility.

Davy's next discovery was the most brilliant of all, though it may be questioned whether it be that which places his talents in the highest point of view. The composition of the alkalies by galvanism had been a favourite speculation with several philosophers; but the want of a sufficient power had always opposed an obstacle to success. Davy had the command of vast galvanic power, and applied it to this problem. His first attempts were made on solutions of potash, without effect; his next efforts were made on fused potash placed on a disc of platinum, connected with the negative pole, and having its upper surface in contact with the positive wire. The potash began to fuse; strong effervescence took place at the positive wire, while metallic globules appeared at the other, which continued to form, and speedily to burn and explode with a very bright flame. He soon discovered a method of repressing their combustibility, by investing them with a film of naphtha; by which means he was enabled to collect the metallic globules for examination.

He found that they were so light as to float in every fluid except recently distilled naphtha; that they had the brilliancy of mercury; that at the ordinary temperature of the air they are malleable, and so soft as to be spread out with a knife; that this metal melts at about 150° Fahrenheit, but at 32° it is a hard crystalline solid, brittle, and extremely splendid; and that in all its states it is a perfect conductor of electricity; in short, that it possesses every general property hitherto recognised in metals, except its extremely low specific gravity. The metallic globules were soon converted into potash in the air; and when brought into contact with water, or even with ice, instantly took fire and burnt, giving rise to potash. The effervescence at the opposite pole he ascertained to be owing to the evolution of oxygen gas. To the metal thus obtained he gave the name of potassium. The rapidity and energy with which potassium attracts oxygen from almost all bodies, showed that it is a valuable instrument of analysis in the hands of the chemist. Davy pursued a similar process with pure soda, and obtained from it a metal of analogous properties, to which he gave the name of sodium.

This splendid discovery appears to have been made in October 1807, was read in November of that year to the Royal Society; and in the following year the results of Davy were fully confirmed by Gay-Lussac and Thenard, who succeeded in decomposing potash by iron filings in a red-hot gun-barrel. In the Bakerian lecture of 1807, Davy mentions the probability of the earths having also metallic bases; but his discoveries were suspended, and very nearly closed for ever, by a severe illness, attended with fever and delirium, which attacked him soon after the reading of his second Bakerian lecture, the consequence of severe bodily exertion and high mental excitement. In March 1808 he was able to resume his labours; but during this interval, baryta and lime had been decomposed by Berzelius and Pootin, who obtained the result by negatively electrifying mercury in contact with portions of the pure earths. Their oxygen was thus driven off, and their bases united into amalgams with the mercury.

These experiments were communicated to Davy, who, in June 1808, read a memoir on that subject to the Royal Society. His paper then describes the amalgamation of strontia, and his process for obtaining the amalgam from magnesia. He also stated that he had succeeded in obtaining the metal of barytes from the amalgam; that it was white like silver, of a higher specific gravity than water, and fluid below a red heat. He attempted unsuccessfully to decompose argil, silic, and zircon, though the results showed a high probability of their having metallic bases. The curious experiment of amalgamating ammonia had occurred to Berzelius and Pootin, and they had communicated the result to Davy. This new subject he pursued with eagerness, and confirmed their results, but could not succeed in distilling off, as he seems to have expected, the compound metallic basis; an idea founded on analogy, but not very probable. It is needless to discuss the various conjectures on the nature of the new metals of the alkalies and earths, to which the discoveries of Davy gave rise; some of the ablest chemists of the day considered them as probable compounds of hydrogen, with some unknown bases. This opinion has not derived any confirmation from subsequent research; and, with regard to the ammoniacal amalgam, it is now generally regarded, not as a true metallic alloy, but as a species of mechanical mixture of ammonia, or its elements, with mercury.

The third Bakerian lecture, read in December 1808, and its appendix of next spring, contain an account of various attempts to effect the decomposition of certain bodies which had not been resolved into their elements. The subjects discussed in this paper were handled with his usual ingenuity; but his success did not equal his own or the public expectation. The only certain result was the proof that hydrogen could not be obtained by any known means from potassium, and that therefore we ought to consider it as a simple body.

In his experiments on ammonia, by the medium of potassium, he obtained an olive-coloured substance, which he considered as an amalgam, and appears to have been sanguine in the idea that he had decomposed nitrogen in this process; but was afterwards compelled to admit his failure. His next inquiries were into the nature of sulphur, phosphorus, and carbon, which he suspected to contain hydrogen, and his experiments led him to believe that these substances contained it in minute quantities; but his conclusions are now considered as erroneous, and the minute portion of hydrogen obtained is regarded as due to the presence of water in the inflammables, or to the obstinacy with which some of them absorb and retain different gases. The third subject discussed was the nature of boracic acid, from which he obtained a basis, by him then considered as of a metallic nature; but he was anticipated on this subject by Gay-Lussac and Thenard, who investigated the subject more completely, established the analogy of the radicle of boracic acid with carbon, and the substance is now called boron. The other subject of inquiry, "The Nature of Muriatic and Oxymuriatic Acids," is remarkable as an ingenious defence of a theory of their formation, which he mainly contributed some time afterwards to overthrow.

It may be interesting to remark, that the original 500 plate batteries of the institution were so worn in the course of Davy's experiments as to be unserviceable; but a liberal voluntary subscription among the members, in July 1808, put him in possession of the most powerful Voltaic battery ever constructed, consisting of 2000 double plates, with a surface equal to 128,000 square inches. The results, however, produced with this stupendous power did not add one new fact of any importance to science. All Davy's splendid Voltaic discoveries were made before it was in use, and it only served to show the phenomena of galvanism with greater brilliancy.

The fourth Bakerian lecture, read in November 1809, contained the same views, and added little to scientific discovery, though every part of it exhibits the talent and ingenuity of the author; but in his researches on oxymuriatic acid, and on the elements of muriatic acid, we find Davy overturning the theory he had laboured to defend in former Bakerian lectures, aducing new proofs of the oxymuriatic acid being a simple body, and muriatic acid a compound of that body and hydrogen.

It had indeed been previously shown by Cruickshank, that the mixture of oxymuriatic acid and hydrogen, in equal proportions, produces common muriatic acid; and the same fact had been more thoroughly investigated by Gay-Lussac and Thenard, who proved that no water is formed during the process, and that, in all cases where oxygen is evolved from oxymuriatic acid, water is always present, and muriatic acid invariably appears. Davy not only confirmed and extended the experiments of these philosophers, but, as it appears to us, has an undoubted claim to priority in deducing from the facts the legitimate consequence, viz. that oxymuriatic acid is, as Scheele, its discoverer, had supposed, a simple body; and that muriatic acid is a compound of hydrogen and that body, for which he proposed the name of chlorine.

In his Bakerian lecture in 1810, and in his essay read February 1811, he considers the changes which these views render necessary in chemical nomenclature, and announces the discovery of a compound of chlorine and oxygen, to which he gave the name of euchlorine, a term which has been since changed for the more appropriate appellation of peroxide of chlorine, to distinguish it from another compound of these substances, which he discovered while in Italy in 1815, and which is termed the peroxide of chlorine. While on this subject, we may remark, that this latter was discovered while engaged in a controversy with Gay-Lussac on the nature of chloric acid, the discovery of the latter; in which, we are compelled to say, neither the temper nor the philosophic dignity of our countryman appear to advantage.

The reputation of Mr Davy was now at its zenith; and he was invited by the Dublin Society to give a course of lectures on electro-chemical science, which he commenced on the 8th November, and concluded on the 29th of that month, in 1810, and for which he received 500 guineas. The Dublin Society, in the following year, invited him to give two courses, one on the Elements of Chemical Philosophy, and the other on Geology, for which he was remunerated by a sum of L750; and the Provost and Fellows of Trinity College did themselves honour by investing Davy with the degree of LL.D.

In 1811 our author was employed to adopt some means for ventilating the House of Commons; a task which he seems to have undertaken without any previous study of the subject; for his attempts were a signal failure, from a miscalculation of the diameter of the pipes necessary to carry off the vitiated and to supply fresh air to so large a building, and became a source of considerable mortification to himself, as well as of malignant pleasantry to the wittlings of that period.

In the following year, the connection between Davy and the Royal Institution was dissolved, by his giving his farewell lecture on the 9th April 1812.

On the preceding day, he had received the honour of knighthood from the hands of the prince regent; and on the 11th of that month he was married to Mrs Apreece, daughter and heiress of Charles Kerr, Esq. of Kelso, and the possessor of an ample fortune.

This important step is admitted by his warmest friends to have produced a change in the deportment of Davy. From that time he seemed to regard patrician rank, and the adventitious distinctions of society, with no philosophic indifference; and he is alleged to have lowered his ambition to meaner objects than were to be won on the fields of scientific investigation.

During the next two or three years, Sir Humphry Davy produced little important to science; and we find him rather following than directing the steps of others. He made two communications to the Royal Society in 1812. The first was on Some Compounds of Phosphorus and Sulphur, in which the most important matters are two new definite compounds of phosphorus and chlorine, and a proposition to name all the precipitates from aqueous solutions Davy. hydrats, because he found them to contain water in definite proportion. The name was unfortunate, especially as in the same paper he had proposed the prefix hydro for compounds into which hydrogen entered as a definite ingredient. In the second paper he described a detonating compound of chlorine and nitrogen, but which had been some time before discovered in France. The first, and, as it proved, the only volume, ever published of his Elements of Chemical Philosophy appeared in 1812; and in the following year he published his Elements of Agricultural Chemistry, the substance of the lectures which he had some years before delivered to the Board of Agriculture. His paper on fluoric acid read in 1813 to the Royal Society, was little more than a confirmation of the analytic experiments of Ampere, who established that the base of fluoric acid unites with oxygen to form that acid, and that acid with boron to form the fluoboric acid.

In the latter part of 1813, Sir Humphry Davy obtained the permission of the French emperor to travel in France; and in October of that year he went, with his lady and Mr Faraday, to the Continent. His visit to Paris brought him personally acquainted with the principal French savants, among whom he particularly singled out Ampere as his chosen friend; but this feeling was at a subsequent period, we are grieved to say, changed into one of bitter hatred on the part of Davy; who so far forgot himself as to exert all his influence to prevent Ampere's election as a foreign member of the London Royal Society.

The most remarkable circumstance arising out of Davy's visit to Paris was the proof it afforded of his utter want of any relish for the sublimest productions of the pencil and the chisel, with which the French capital then abounded. He was well received by the French philosophers; he was honoured by their flattering attentions; but we are constrained to say that he returned their courtesies with an arrogance and ridiculous affectation of superiority, which justly offended, and tended much more to lower English philosophy than to elevate Davy in their estimation. This was peculiarly unfortunate; for every little feeling of national jealousy seems to have been banished from their minds, and we fear that the odium of want of cordiality must rest with our countryman. But another act of ill-judged interference completed the disgust which his absurd conduct in other respects had excited. Before the time of Davy's visit to France, Courtois had discovered iodine, and Gay-Lussac and Thenard were engaged upon its properties. Some of that substance was given to Davy by Ampere, and he immediately began to examine it. On the 11th of December he offered to the Institute a general view of its nature and relations, and transmitted to London an account of its properties, which was read to the Royal Society on the 20th of January 1814. This paper is introduced with the remark that "Gay-Lussac is still engaged in experiments on this subject; and from his activity and great sagacity a complete chemical history of it may be anticipated." This priority of occupation ought to have prevented Davy from the ungenuous anticipation.

From Paris Davy proceeded, in the end of December, to Montpellier, and from thence to Italy by the Col de Tende. At Genoa and Florence he continued his experiments on iodine, which he obtained from the ashes of various fuscii. At the latter place he made experiments also on the combustion of the diamond with the great lens in the cabinet of natural history; and he discovered that, after the diamond has been once ignited, it will continue to burn with splendour in pure oxygen, though the source of heat has been withdrawn. Thence he proceeded by Rome to Naples, where he was engaged on observations on the phenomena of Vesuvius, and collected specimens of the colours used by the ancients in their pictures, which formed the subject of a memoir to the Royal Society. The most interesting part of this paper is, that the fine blues of the ancients were formed of silex, soda, and copper; and that they may be exactly imitated by strongly heating together three parts of copper filings, fifteen parts of carbonate of soda, and twenty of powdered flint, for two hours. After spending the winter in Italy, he returned on the 23rd of April to London.

The year 1816 is memorable in the history of Sir Humphry Davy, as that in which he turned his attention to a method of preventing the dreadful accidents from explosions of fire-damp in coal-mines. The frequent accidents in the Newcastle and Sunderland collieries from such explosions had given rise to the formation of a society for ascertaining how they could be prevented; and the Reverend Dr Gray, the president, requested Davy's opinion. After he had visited the mines, specimens of fire-damp were transmitted to him in London. He began by an analysis of the gas, and by ascertaining the limits of its exploding properties. He found that it would not explode when mixed with less than six times, or with more than fourteen times its volume of atmospheric air; that air rendered impure by the combustion of a candle will not explode fire-damp, though the candle will still burn for a time; that if a candle be burnt in a close vessel, with small apertures only above and below the flame, no explosion will take place, even in an exploding mixture; that in this case the flame within will be enlarged, but no explosion will reach outward; and that the gas from mines will not explode in a tube less than one eighth inch in diameter. From these principles, Davy proposed several different lamps, some of which strongly resemble the contemporary inventions of Murray and Clauny; but all were finally superseded by the simple lamp of Davy, in which a small oil light was covered by a cylinder of wire gauze.

The introduction of this beautiful invention was for a time violently opposed by prejudice and passion; but the experience of the miners of Britain, Belgium, and other countries, has confirmed its utility and comparative safety. This triumph of Davy's genius, exerted as it was in the cause of suffering humanity, is the noblest monument to his fame; and the debt of gratitude is enhanced by the disinterested manner in which his discovery was freely communicated, without any idea of a pecuniary reward. The coal-owners of Newcastle and its vicinity, impressed with the important services conferred on them by Davy's discovery, presented him with a superb service of plate, embellished with a suitable inscription.

The succeeding years of the life of Sir Humphry Davy, though they do not present any remarkable discoveries, were by no means spent in inactivity. The world is usually unjust in its anticipations from those who have done much, and is apt to feel disappointment at any symptom of relaxation in those who have contributed most to the public excitement.

In 1815, 1816, and 1817, he read various communications to the Royal Society on the subject of fire-damp, and on the nature of flame, for which he received the Rumford medals. In 1818 and 1819 he produced four memoirs "On the fallacy of the experiments in which Water is said to have been produced by the decomposition of Chlorine," on "Some Combinations of Phosphorus," Observ-

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1 This last fact was discovered, however, long before by Grotthus, and was by the late Dr Murray of Edinburgh applied, at the very time Davy was engaged on the subject, to the construction of a safety-lamp for mines, which may be seen in the Edinburgh Philosophical Transactions. vations on the Formation of Mists over Lakes and Rivers," "On Electro-magnetism." In 1818 Sir Humphry, who had made some previous experiments on unrolling the papyri of Herculaneum, was sent by the British government to examine the manuscripts in the Neapolitan museum, in order to attempt on the spot their evolution. He soon satisfied himself that these papyri had not been charred, but altered by the percolation of water, or merely by the application of tuffaceous ashes. His remarks on them, contained in his paper to the Royal Society in 1821, are highly ingenious, but no success attended his labours, probably from the unfortunately irremediable condition of the Herculanean papyri; but he also hints at obstructions thrown in his way by the persons employed in the museum. During this excursion, he published at Naples an account of the thermal baths of Lucian, from the waters of which are deposited silica and oxide of iron, which he conjectures to have been held together in solution in the bowels of the earth; and he inferred that the oxide of iron was held in solution as a protosilicate by silica, which, with Berzelius, he conceived to act the part of an acid.

In 1820 Davy returned to England, and on the death of Sir Joseph Banks, in that year, was elected President of the Royal Society. The opinions of members were divided between him and Dr Wollaston; but the latter persistently refused to be put in nomination, and lent all his influence to support the pretensions of the former. It is doubtful how far Sir Humphry's pursuits and temperament qualified him for filling this station with advantage to the society. With regard to his high claims to the distinction, there can only be one opinion; but unfortunately he lent himself to the petty cabals of a coterie during his possession of the chair. His ill-concealed partiality for the aristocracy of birth over that from which he alone drew his own rank, the aristocracy of talent; the preposterous assumption in his own person, on some occasions, of a patrician haughtiness, and a neglect of the ordinary courtesies of society, procured him many enemies; and when he resigned the chair, he had become one of the most unpopular presidents that had for years ruled the society.

In the year 1821-22, he continued to make some experiments on electro-magnetism, and electricity in vacuo, but in his results he was anticipated by other observers; and in his memoir on electrical phenomena in vacuo, he has not arrived at any definite conclusion, except that electric light, and attractions and repulsions, may be exhibited in the most perfect vacuum we can form. In his paper on the fluids contained in the cavities of natural crystals, Davy showed that these cavities were filled with fluids less dense than those under atmospheric pressure; and he thence inferred that such crystals must have had an igneous origin. In most of his experiments the fluid seems to have been water; but in some later investigations, particularly in those of Dr Brewster, the fluids in crystals appear to be more varied in their nature.

In 1823 the interesting discovery by Mr Faraday, of the condensation of certain gases by mechanical pressure, induced Sir Humphry Davy to repeat the experiment; and he succeeded, by heating them in strong sealed tubes, to convert sulphurous acid and prussic acid gases into liquids. His paper on this subject contains some rather fanciful conjectures on the probable application of these condensed gases as mechanical powers.

In the same year he investigated the cause of the rapid decay of copper sheathing on ships. The subject was proposed by the admiralty to the president and council of the Royal Society, and Sir Humphry undertook the investigation of the cause, and its remedy. It occurred to him, that as sea-water only acts on the copper when it is in a positive state of electricity; if he could render it slightly negative, it would be defended from the action of sea-water. For this purpose he attached to plates of copper portions of iron or of zinc, and he had the satisfaction of finding that they remained unchanged on immersion in sea-water. He therefore communicated to government, in January 1824, his discovery of a remedy for the defects of copper sheathing; and immediate orders were given to put his scheme into practice on a cutter, while models were fitted up and floated in sea-water at Somerset House. These trials appeared so perfectly satisfactory, that immediately orders were issued to apply plates of iron, or "protectors" as they were called, to many ships belonging to the royal navy; and many merchant-men were fitted out with the same.

A short experience however showed, that though the copper was protected from corrosion, an unlooked-for evil of another kind speedily arose. The bottoms of the "protected" ships soon became extremely foul. The negative state of the copper sheathing favoured the deposition of the calcareous matter from sea-water, the growth of seaweeds, and the adhesion of enormous lepadites and balani everywhere to the copper; so as most seriously to impede the sailing of the ships. This was proved, not only in the navy, but extensively in the merchant service in London, Liverpool, and other sea-ports; so that in spite of the ridiculous attempts of a clique of the pretended friends of our philosopher at first to deny, and afterwards to conceal the facts, orders were everywhere given to remove the protectors. This was a severe mortification to Davy, whose temper it appears greatly to have ruffled. He had read an elaborate memoir on the subject to the society in June 1825, and the navy order for the discontinuance of the protectors followed in July. The infirm state of Sir Humphry's health probably increased his irritability; and much of what has been placed to the mortification of unsuccessful exertion, and sensibility to ill-applied and unjust sarcasm on this occasion, ought, in all probability, to be ascribed to the approaches of disease, that was undermining the constitution of the philosopher. In 1826 his health had visibly declined, and his friends began to perceive that he was with difficulty able to indulge in his favourite sports of angling and shooting. On returning to London from Somersetshire he was unable to attend the anniversary dinner of the Royal Society. In January 1827 he published his six anniversary discourses on awarding the royal and Copley medals. Early in 1827 he went abroad, and soon reached Ravenna, where he seemed to derive some intermission of his ailments, which he describes as arising "from determination of blood to the brain; at last producing the most alarming nervous symptoms, and threatening the loss of power and life." In the summer, to avoid the heats, he removed to Salzburg, from which city he sent in his resignation of the president's chair of the Royal Society, from a conviction of the necessity of mental and bodily repose. In the end of autumn he returned to England, and removed to London in the winter, where he published his Salmonia in the spring of 1828. This work, though inferior in interest to the delightful pages of Isaac Walton, in imitation of which it is written, is yet an interesting performance.

Shortly before Davy quitted England, he communicated to the Royal Society his paper on Volcanoes, chiefly from observations made on Vesuvius in 1820; in which he advocates the idea that volcanic phenomena depend on the oxidation of the bases of the alkalies and earths (an opinion which was before maintained by Humboldt), while Davy at the same time thinks that there are strong proofs, in the increasing temperature as we descend in mines, of a central fire. In 1828 Sir Humphry Davy quitted his native country for the last time, and spent the summer and autumn in his favourite amusement of angling and in shooting near Laybach. In the winter he descended into Italy, and fixed his residence at Rome, whence he sent his last communication to the Royal Society, Remarks on the Electricity of the Torpedo, which was written in Illyria in October. The chief peculiarity of this paper is his finding that the electricity of the torpedo has no effect on the most delicate galvanometer, which he ascribes to the torpedo's influence being exerted, not in a continued stream, but in instantaneous and successive shocks; an idea confirmed by the same want of magnetic influence in moderate shocks from the Leyden phial.

Sir Humphry had suffered from a previous paralytic attack; at Rome he had another, which greatly alarmed his friends, and made his wife and his brother hasten to his assistance. They were soon with him; and he having become eager to quit Rome for Geneva, the party set out by easy journeys for the latter place. On the 25th May he slept at Chambery, and at three next afternoon arrived at Geneva, dined heartily at four o'clock, and was unusually cheerful. During the night an attack of apoplexy came on, and he expired at three o'clock in the morning of the 30th May 1829. His remains were deposited, with all the honours which a public funeral could bestow, in the State where he had breathed his last.

A posthumous work, entitled Consolations in Travel, or the Last Days of a Philosopher, shows a high degree of fancy, and an almost poetic inspiration; and, whether we regard the matter or the manner, is an evident offspring of a bold imagination.

We have sufficiently characterized the various productions of this eminent man in our review of his life. We have alluded to those little infirmities which mix themselves with the aspirations of genius with no unfriendly intention. They are specks on its bright mirror, which they do not obscure; but as everything connected with such a man belongs to history, they should not be passed over in silence; for while the example of his great qualities are held up to animate the exertions of unfriended talent struggling with obscurity, the consequences of his infirmities may become valuable lessons to check the presumption of successful genius.