10 Memoir of Sir Humphry Davy, Bart. gave up all his views of the medical profession, and devoted himself entirely to chemistry. Mr. Davy's first experiments as Professor of Chemistry in the Royal Institution were made on the substance employed in the process of tanning, with others to which similar properties were ascribed, in consequence of the discovery made by Mr. Seguier, of Paris, of the peculiar vegetable matter, now called tannin. He was, during the same period, frequently occupied in experiments on galvanism. In 1802 Mr. Davy commenced a series of lectures before the Board of Agriculture, which was continued for ten years. It contained much popular and practical information, and was among the most useful of Mr. Davy's scientific labours; for the application of chemistry to agriculture is one of its most important results. So rapid were the discoveries of the author, that in preparing these discourses for publication, a few years afterwards, he was under the necessity of making several alterations, to adapt them to the improved state of chemical knowledge, which his own labours had, in that short time, produced. In 1803 he was elected a Fellow of the Royal Society, and in 1805 a member of the Royal Irish Academy. He now enjoyed the friendship of the most distinguished literary men and philosophers of the metropolis, and enumerated among his intimate friends, Sir Joseph Banks, Cavendish, Hatchett, Wollaston, Children, Tennant, and other eminent men. At the same time he corresponded with the principal chemists of every part of Europe. In 1806 he was appointed to deliver, before the Royal Society, the Bakerian lecture, in which he displayed some very interesting new agencies of electricity, by means of the galvanic apparatus. Soon afterwards, he made one of the most brilliant discoveries of modern times, in the decomposition of two fixed alkalies, which, in direct refutation of the hypothesis previously adopted, were found to consist of a peculiar metallic base, united with a large quantity of oxygen. These alkalies were potash and soda, and the metals thus discovered were called potassium and sodium. Mr. Davy was equally successful in the application of galvanism to the decomposition of the earths. On the 22d of January, 1807, [July, he was elected Secretary of the Royal Society; and in the same year the National Institute of France allotted him a prize of 3000 livres for his paper on Chemical Affinities. During the greater part of 1810 he was employed on the combinations of oxymuriatic gas and oxygen, and towards the close of the same year he delivered a course of lectures before the Dublin Society, and received from Trinity College, Dublin, the honorary degree of LL.D. In 1812 Mr. Davy married. The object of his choice was Jane, daughter and heiress of Charles Kerr, of Kelso, Esq., and widow of Shuckburgh Ashby Apreece, Esq., eldest son of the present Sir Thomas Hussey Apreece, Bart. By his union with this lady, Mr. Davy acquired not only a considerable fortune, but the inestimable treasure of an affectionate and exemplary wife, and a congenial friend and companion, capable of appreciating his character and attainments. On the 9th of April, only two days previously to his marriage, he received the honour of knighthood from the Prince Regent, being the first person on whom his Royal Highness conferred that dignity. We now arrive at the most important result of Sir Humphry Davy's labours, the invention of the SAFETYLAMP for coal mines, which has been generally and successfully adopted throughout Europe. The frequency of accidents, arising from the explosion of the fire-daup, or inflammable gas of the coal mines, mixed with atmospherical air, occasioned the formation of a committee at Sunderland, for the purpose of investigating the causes of these calamities, and of endeavouring to discover and apply a preventive. Sir Humphry received an invitation, in 1815, from Dr. Gray, one of the members of the committee; in consequence of which he went to the North of England, and visiting some of the principal collieries in the neighbourhood of Newcastle, soon convinced himself that no improvement could be made in the mode of ventilation, but that the desired preventive must be sought in a new method of lighting the mines, free from danger, and which, by indicating the state of the air in the part of the mine where the inflammable air was disengaged, so as to render the atmosphere explosive, should oblige the miners to retire till 1829.] Memoir of Sir Humphry Davy, Bart. the workings were properly cleared. The common means then employed for lighting the dangerous part of the mines consisted of a steel wheel revolving in contact with flint, and affording a succession of sparks: but this apparatus always required a person to work it, and was not entirely free from danger. The fire-damp was known to be light carburetted hydrogen gas; but its relations to combustion had not been examined. It is chiefly produced from what are called blowers or fissures in the broken strata, near dykes. Sir Humphry made various experiments on its combustibility and explosive nature; and discovered that the fire-damp requires a very strong heat for its inflammation; that azote and carbonic acid, even in very small proportions, diminished the velocity of the inflammation; that mixtures of the gas would not explode in metallic canals or troughs, where their diameter was less than one-seventh of an inch, and their depth considerable in proportion to their diameter; and that explosions could not be made to pass through such canals, or through very fine wire sieves, or wire-gauze. The consideration of these facts led Sir Humphry to adopt a lamp, in which the flame, by being supplied with only a limited quantity of air, should produce such a quantity of azote and carbonic acid as to prevent the explosion of the firedamp, and which, by the nature of its apertures for giving admittance and egress to the air, should be rendered incapable of communicating any explosion to the external air. These requisites were found to be afforded by air-tight lanterns, of various constructions, supplied with air from tubes or canals of small diameter, or from apertures covered with wire-gauze, placed below the flame, through which explosions cannot be communicated; and having a chimney at the upper part, for carrying off the foul air. Sir Humphry soon afterwards found that a constant flame might be kept up from the explosive mixture issuing from the apertures of a wire-gauze sieve. He introduced a very small lamp in a cylinder, made of wiregauze, having six thousand four hundred apertures in the square inch. He closed all apertures except those of the gauze, and introduced the lamp, burning brightly within the cylinder, into 11 a large jar, containing several quarts of the most explosive mixture of gas from the distillation of coal and air; the flame of the wick immediately disappeared, or rather was lost, for the whole of the interior of the cylinder became filled with a feeble but steady flame of a green colour, which burnt for some minutes, till it had entirely destroyed the explosive power of the atmosphere. This discovery led to a most important improvement in the lamp, divested the fire-damp of all its terrors, and applied its powers, formerly so destructive, to the production of a useful light. Some minor improvements, originating in Sir Humphry's researches into the nature of flame, were afterwards effected. Experiments of the most satisfactory nature were speedily made, and the invention was soon generally adopted. Some attempts were made to dispute the honour of this discovery with its author, but his claims were confirmed by the investigations of the first philosophers of the age. The coal owners of the Tyne and Wear evinced their sense of the benefits resulting from this invention, by presenting Sir Humphry with a handsome service of plate worth nearly two thousand pounds, at a public dinner at Newcastle, October 11, 1817. In 1813 Sir Humphry was elected a corresponding member of the Institute of France, and Vice-President of the Royal Institution. He was created a Baronet Oct. 20, 1818. In 1820 he was elected a Foreign Associate of the Royal Academy of Sciences at Paris, in the room of his countryman Watt; and in the course of a few years most of the learned bodies in Europe enrolled him among their members. Many pages might be occupied with the interesting details of Sir Humphry Davy's travels in different parts of Europe for scientific purposes, particularly to investigate the causes of volcanic phenomena, to instruct the miners of the coal districts in the application of his safety-lamp, to examine the state of the Herculaneum manuscripts, and to illustrate the remains of the chemical arts of the ancients. He analysed the colours used in painting by the ancient Greek and Roman artists. His experiments were chiefly made on the paintings in the baths of Titus, the ruins called the baths of Livia, in the remains of other palaces 12 Memoir of Sir Humphry Davy, Bart. and baths of ancient Rome, and in the ruins of Pompeii. By the kindness of his friend Canova, who was charged with the care of the works connected with ancient art in Rome, he was enabled to select with his own hands specimens of the different pigments that had been formed in vases discovered in the excavations, which had been lately made beneath the ruins of the palace of Titus, and to compare them with the colours fixed on the walls, or detached in fragments of stucco. The results of all these researches were published in the Transactions of the Royal Society for 1815, and are extremely interesting. The concluding observations, in which he impresses the superior importance of permanency to brilliancy in the colours used in painting, are especially worthy the attention of artists. On his examination of the Herculaneum manuscripts, at Naples, in 1818-19, he was of opinion they had not been acted upon by fire, so as to be completely carbonized, but that their leaves were cemented together by a substance formed during the fermentation and chemical change of ages. He invented a composition for the solution of this substance, but he could not discover more than 100 out of 1,265 manuscripts, which presented any probability of success. Sir Humphry returned to England in 1820, and in the same year his respected friend, Sir Joseph Banks, President of the Royal Society, died. Several discussions took place respecting a proper successor, when individuals of high and even very exalted rank were named as candidates. But science, very properly in this case, superseded rank. Amongst the philosophers whose labours had enriched the Transactions of the Royal Society, two were most generally adverted to, Sir Humphry Davy and Dr. Wollaston; but Dr. Wollaston, who had received from the council of the Society the unanimous compliment of being placed in the chair till the election by the body in November, declined any competition with his friend Sir Humphry Davy. Sir Humphry retained his seat as President till the year 1827, when, in consequence of procrastinated ill health, in great measure brought on by injuries occasioned to his constitution by scientific experiments, he was induced, by medical advice, to retire to the con [July, tinent. He accordingly resigned his seat as President of the Royal Society, the chair being filled, pro temp. by Davies Gilbert, Esq. who at the Anniversary Meeting, Nov. 30, 1827, was unanimously elected President. During his retirement on the Continent, Sir Humphry continued to communicate the results of his labours to the Royal Society, and at the anniversary meeting of the year 1827, one of the royal medals was awarded to him for a series of brilliant discoveries developing the relation between electricity and chemistry. Upon this interesting occasion, Mr. Davies Gilbert spoke as follows: "It is with feelings the most gratifying to myself, that I now approach to the award of a Royal medal to Sir Humphry Davy; having witnessed the whole progress of his advancement in science and in reputation, from his first attempts in his native town, to vary some of Dr. Priestley's experiments on the extrication of oxygen from marine vegetables, to the point of eminence which we all know him to have reached. "It is not necessary for me more than to advert to his discovery of nitrous oxide; to his investigation of the action of light on gases on the nature of heat; to his successful discrimination of proximate vegetable elements; nor to his most scientific, ingenious, and useful invention, the safetylamp, an invention reasoned out from its principles, with all the accuracy and precision of mathematical deduction. "The particular series of discoveries for which the Royal medal has been awarded, are those which develop the relation between electricity and chemistry. "Soon after Sir Humphry Davy had invitation from Count Rumford, an invitabeen seated at the Royal Institution by an tion founded on his first production,—a paper on the nature of heat,-our late President began his experiments and investigations on electric chemistry: a most powerful Voltaic apparatus was fortunately placed at his disposal; and in his hands electric chemistry soon became the most important branch of practical science: important from its immediate energies and powers; but much more so from the general laws of nature, which it has laid open to our view. of combustion, was discovered, possessing "A new acidifying principle, or supporter the same negative electric properties as oxygen. Muriatic acid disclosed its real composition. The oxymuriates were transferred to their proper class. The alkalies were reduced into metals; and the earths were proved to be similar oxides. But in the progress of these experiments a dis 1829.1 Memoir of Sir Humphry Davy, Bart. covery was made, surpassing all the wonders attributed to alchemy. Three basins were arranged in a straight line, each containing water, and to the middle basin some neutral salt was added. The three were connected by moistened syphons of asbestos: the opposite piles of a Voltaic battery were then applied to the extreme vessels; and in a short time the neutral salt disappeared from the middle basin, and its constituent parts were found separated; the acid attracted to the positive pile of the battery, the alkali to the negative. This astonishing result, followed up by other experiments, led to the conclusion that chemical energies may be increased, diminished, or even inverted, by the superinduction of electric powers homogeneous with or dissimilar from their own. This metastasis in the hands of physiological inquirers promises to conduct them to discoveries of the utmost importance in the functions of life. I flatter myself that it is now actually in such hands. “The principle of varying or modifying chemical energies by those of electricity has been applied by the invention, in a manner the most philosophical, and on a scale the most extensive. "The copper sheathing of ships and vessels had been found to corrode in the short period of a single voyage, being converted into an oxide through the raedium of some acid, or at least of a decompounded substance, occupying the negative extremity of the electric scale. The copper must therefore be positive in respect to the body decomposed or attracted. A reference was made by the Government to the Royal Society, with the hope of discovering some remedy for this most serious evil. Grounded on a perfect knowledge of chemical and of electric powers, it immediately occurred to the illustrious discoverer of their relations one to the other, that if a substance more positive than copper, and in contact with it, could be exposed to the corroding action, that the copper would, by induction, be rendered less positive, and therefore indisposed to combine with any other negative body. "Experiments the most satisfactory were then made on a small scale; and in conse quence of their success, plates of zinc, and afterwards of iron, were applied to ships' bows; and the copper has been fully and completely protected. The theory and the experiments have been confirmed in the most ample manner. A defect has indeed occurred in practice, from the over success of protection. The induction of negative powers to the copper has gone too far; they have caused it to act on the compounds in an opposite direction, by attracting to itself the earths and alkalies, thus affording attachments to the marine vegetables which the copper was intended to prevent. This appears to me, however, susceptible of a cure. 13 war. I am sufficiently advanced in years to remember the American-revolution Ships were then first sheathed with copper: they were preserved clean from weeds, nor was the copper corroded: but the ships were fastened together by iron bolts, and these, to the utter astonishment of every one, decayed; and the ships became unable to sustain the ordinary straining in gales of wind. For some time the effect could not be traced to its cause, for galvanism was then unknown; but at last bolts made of bronze were substituted for those of iron, and immediately the copper failed. When the theory has therefore been modified by experience on the principle of these empiric trials during the American war, I cannot hesitate in predicting complete practical success, with full glory to the illustrious individual who deduced the practice from theory, and with ample advantage to all those who may then bring the practice into beneficial use. "Sir Humphry Davy having last year communicated a paper to the Society in continuation of his former inductions and generalization on chemical and electric energies, there cannot be a doubt but that the only obstacle against his then receiving a Royal medal, on the first occasion that the Society had it to bestow, was his occupying this chair. That obstacle, unhappily for science, no longer exists; and the Royal Society take this earliest opportunity of testifying their high estimation of these talents and of these labours which all Europe admires. We trust and hope, although our late President has been induced by medical advice to retire from the agitation of active public stations, that his most valuable life will be long spared; and that energies of mind may still be displayed to this Society and to the civilized world, equal to those which have heretofore rendered immortal the name of Davy." Sir Humphry Davy was in every respect an accomplished scholar, and was well acquainted with foreign languages. He always retained a strong taste for literary pleasures; and his philosophical works are written in a perspicuous and popular style, by which means he has contributed more to the diffusion of scientific knowledge than any other writer of his time. His three principal works are, "Chemical and Philosophical Researches," "Elements of Chemical Philosophy," and "Elements of Agricultural Chemistry," and the two last are excellently adapted for elementary study. His numerous pamphlets and contributions to the Transactions of the Royal Society have the same rare merit of conveying experimental knowledge in the 14 Memoir of Sir Humphry Davy, Bart. most attractive form, and thus reducing abstract theory to the practice and purposes of life and society. The results of his investigations and experiments were not therefore pent up in the laboratory or lecture-room where they were made, but by this valuable mode of communication, they have realized, what ought to be the highest aim of science, the improvement of the condition and comforts of every class of his fellow creatures. Thus, beautiful theories were illustrated by inventions of immediate utility, as in the safetylamp for mitigating the dangers to which miners are exposed in their labours, and the application of a newlydiscovered principle in preserving the life of the adventurous mariner. Yet splendid as were Sir Humphry's talents, and important as have been their application, he received the honours and homage of the scientific world with that becoming modesty which universally characterizes great genius. Apart from the scientific value of Sir Humphry's labours and researches, they are pervaded by a tone and temper, and an enthusiastic love of nature, which are as admirably expressed as their influence is excellent. We trace no mixture of science and scepticism, and in vain shall we look for the spawn of infidel doctrine. The same excellent feeling breathes throughout "Salmonia, or Days of Fly-fishing," a volume published last year, and one of the most delightful labours of leisure ever seen. Not a few of the most beautiful phenomena of Nature are here lucidly explained, yet the pages have none of the varnish of philosophical unbelief, or finite reasoning. The work is arranged in a series of conversations, and we are told in the preface, that "these pages formed the occupation of the author during several months of severe and dangerous illness, when he was wholly incapable of attending to more useful studies, or of following more serious pursuits. They formed his amusement in many hours, which otherwise would have been unoccupied and tedious." "The conversational and discursive style were chosen as best suited to the state of the health of the author, who was incapable of considerable efforts and long continued exertion." The volume is dedicated to Dr. Babington, "in remembrance of some delightful days passed in his society, and in gratitude [July, for an uninterrupted friendship of a quarter of a century:" and the likeness of one of the characters in the conversations to that estimable physician above-named, has been considered well drawn, and easily recognisable by those who enjoy his acquaintance. Sir Humphry spent nearly the whole of last summer in fowling and fishing in the neighbourhood of Laybach, and it has been related by a gentleman who accompanied him on a shooting excursion, that the relative weight of the various parts of each bird, the quantity of digested and undigested food, &c. was carefully noted down by the observant naturalist. It is believed that he was preparing for a large work on natural history.. The great philosopher closed his mortal career at Geneva. He had arrived in that city only the day before, having performed his journey from Rome by easy stages, without feeling any particular inconvenience, and without any circumstances which denoted so near an approach to the last debt of nature. Sir Humphry had been for some months a resident at Rome, where he had had a serious and alarming attack of a paralytic nature, but from which he was apparently, though slowly, recovering; but his most sanguine friends hardly ventured to hope that his valuable life would be much longer preserved. Lady Davy had joined him in Rome, on hearing of his alarming state, as had also his brother, Dr. John Davy, physician to the forces in Malta. The event was no sooner known than his afflicted widow received the condolences and affectionate offers of services from the most distinguished individuals of this place; amongst whom were Mr. A. de Condolle, the eminent botanist, and Mr. Sismondi, the historian; both equally beloved for their amiable character, and illustrious throughout Europe for their works. Mr. de Condolle took charge of all the details of the interment; and the government of the Canton, the academy of Geneva, the consistory of the Genevan Church, and the societies of arts, and of natural philosophy and history, together with nearly all the English residents, accompanied the remains to the burying-ground, where the English service was performed by the Rev. John Magers, of Queen's College, and the Rev. Mr. Burgess. The |