Sir Humphry Davy
I T was the afternoon of market-day in Penzance, and Market Jew Street was almost deserted save for the gossips, who were scattered in little knots here and there; for, next to the buying and selling of goods the bartering of news was held to be an indispensable feature of the weekly gathering. Round the doorway of the old 'Starr Inn' some score or so of men were engaged in drinking and in discussing the topics of the market, preparatory to starting on their homeward journey. In the inn-yard were standing several of the country carts which had brought the folk into the town in the early hours of the day, whilst the horses that were to draw them home were still enjoying their rest in the stables.
From one of the carts a chubby-faced schoolboy was haranguing a circle of boys gathered around him. Every minute a straggler would join the circle, and nudge his neighbour in schoolboy fashion to inquire what the speech was about. As his audience increased the speaker waxed more eloquent, waving his arms, or drawing imaginary outlines in the air to illustrate or emphasize his story. When, on half-holidays, word was passed round that Humphry Davy had a story to tell, the story-teller was sure of a good and attentive audience. As for the materials out of which he fashioned his stories, they were derived from various sources, but chiefly, at first, from books. Even as early as eight years old the boy was an omnivorous reader, and the rate at which he devoured a book was only equalled by the accuracy with which he could remember what he had read. His first book, the Pilgrim's Progress, gave him special delight, and by firing his imagination led him to seek for legends in places as well as in books. Nor had he far to seek. The countryside abounded in folklore of every description; there was scarcely a village or hamlet that could not boast of a witch, living or dead, to whose machinations all sorts of misfortunes, real and imaginary, were ascribed; whilst every cave and rocky fastness along the wild and rugged coast had its legend of the past.
To tales and legends of land, sea, and rock Humphry Davy listened with eagerness, and his natural gift for story-telling enabled him to weave them into yarns for the entertainment of his school-fellows; also, he was a capital hand at the flying of kites, the carving of turnip-lanterns, and the making of fireworks, with a 'speciality' of his own invention in the shape of a detonating compound, which went by the delightful name of 'Thunder-powder'.
The boyhood of Humphry Davy dates back to a period of more than a century ago, for he was born on December 17, 1778. The place of his birth was Penzance, where his father, Robert Davy, worked as a wood-carver. During the childhood of Humphry the family, consisting of Humphry, the eldest child, John, the second son, and three daughters, removed to Varfell, and shortly after he was placed at a preparatory school. Later Davy was sent to the Penzance grammar school, under the Rev. I. C. Coryton, who had an unpleasant way of reminding his scholars of their deficiencies by pulling their ears—a treatment to which Davy showed his resentment by appearing one day with a huge plaster on each ear, gravely explaining that he had 'put the plasters on to prevent mortification'. His love of reading and of story-telling were accounted a species of idleness, or the vagaries of a mind not sufficiently tractable to confine itself to the narrow limits of classical studies. He gave further proof of this idleness by seizing every opportunity for fishing the streams, or wandering off along the coast to explore the caves, with a notebook or sketch-book for his companion. At other times he would 'shut himself up in his room, arrange the chairs, and lecture to them by the hour together'. Yet again he would steal time from school to spend it in the company of a Quaker saddler in the town, named Robert Dunkin, a clever mechanic, who, it is said, gave Davy his first taste of experimental science.
In 1794 Robert Davy died, the widow returned with her family to Penzance, where she set up a small millinery business in partnership with a friend, and Humphry was apprenticed, in February of the following year, to Mr. John Bingham Borlase, a surgeon-apothecary of the town. Dunkin, Humphry's Quaker friend, had already imbued him with a taste for science, and the resources of the apothecary's dispensary soon made him a chemist. His garret bedroom was in these days the scene of many experiments, and his apparatus, where not made by his own hands, consisted of pots and pans borrowed from the kitchen, tobacco pipes, and vessels 'annexed' from the dispensary. The experiments were of a simple kind, such as the preparing of gases, effects of acids and alkalis on vegetable colours, the solution and precipitation of metals, etc., and as there was no fireplace in his bedroom he was obliged to bring his crucible down to the kitchen. It is interesting to note the order of his studies: thus, his attention was first given to the theory of chemistry as expounded by the great French chemist Lavoisier; he speculated upon what he read; the speculations led him to experiment; and experimenting led him once more to speculate. The immediate result of the chemical operations was to cause the elder inmates of the house to exclaim: 'Humphry is incorrigible; he will blow us all into the air!'
He was, as we have seen, launched upon scientific speculations and seized with the fever of discovery, even before he had got his hand in with experimental work. This was the earliest indication of that tendency to 'put the cart before the horse' which characterized his scientific attitude in later years. Said Robert Dunkin to him one day: 'I tell thee what, Humphry, thou art the most quibbling hand at a dispute I ever met with in my life.'
On his evening walks to Marazion, to drink tea with his aunt, he takes with him his geological hammer and seeks for rock specimens on the beach. Instead of physicking his master's patients he is hammering the rocks, and, according to Dr. Paris, he 'paid much more attention to philosophy than to physic', and 'thought more of the bowels of the earth than of the stomachs of his patients'. We have seen how, as a boy, he used to lecture the chairs; and this fondness for declaiming seems to have pursued him when an apprentice. He indulged in it during his walks and solitary rambles. On one occasion it is recorded of him that, on his way to visit a poor patient in the country, in his fervour of declamation he threw out of his hand a vial of medicine which he had to administer, and that, when he arrived at the bedside of the poor woman, he was surprised at the loss of it!
On October 2, 1798, having been appointed assistant to Dr. Beddoes, a well-known scientist, Davy quitted Penzance for Bristol, reaching his destination in time to witness the arrival of the mail-coach from London, 'covered with laurels and ribbons, and bringing the news of Nelson's glorious victory of the Nile.'
Nine days later he writes to his mother in the highest of spirits: 'I have now a little leisure time, and I am about to employ it in the pleasing occupation of communicating with you an account of all the new and wonderful events which have happened to me since my departure.' He is very pleased with his hosts and their kind reception of him, with the house, his rooms, and above all with the 'excellent laboratory'. Beddoes he describes as 'one of the most original men I even saw—uncommonly short and fat, and with little elegance of manners, and with no external signs of genius or science, extremely silent—in fact, a bad companion'. Beddoes (who had previously seen Davy's MS. Essay on Heat and Light) has paid him 'the highest compliments on my discoveries, and has, in fact, become a convert to my theory, which I little expected'. Mrs. Beddoes he finds to be the reverse of her husband—'extremely cheerful, gay, and witty. With a cultivated understanding and excellent heart, she combines an uncommon simplicity of manners. We are already very great friends.' He sums up by saying: 'My expectations are answered, and my situation is just what I could wish.'
Mrs. Beddoes, it should be noted, was Anna Edgeworth, a sister of Maria Edgeworth, the author; and it was through Mrs. Beddoes that Davy became acquainted with the Edgeworth family, as well as with Southey, Coleridge, the Tobins, and others.
In 1798 appeared Contributions to Physical and Medical Knowledge, principally from the West of England; collected by Thomas Beddoes, M.D., the first half of this volume being occupied by two essays by Davy—'On Heat, Light, and the Combinations of Light, with a new Theory of Respiration,' and 'On the Generation of Phosoxygen [Oxygen gas], and the Causes of the Colours of Organic Beings'.
'With all their faults of hasty speculation, of partial reasoning, and, in very many instances, erroneous experiments,' says Dr. John Davy, 'I cannot help thinking that posterity will pass on these essays a sentence different from that of their author, and would, on no account, have them blotted out from the records of science; this is the true test of their value, and of their deserving, not the unqualified censure which some critics have bestowed on them, but the qualified praise which they who know how difficult is the investigation and discovery of truth, and the navigation of the ocean of science, will most willingly give.'
How Davy learnt his lesson—the lesson of his life in regard to science—is best told by extracts from his notebooks. In August of the year in which the essays appeared he wrote: 'When I consider the variety of theories that may be formed on the slender foundation of one or two facts, I am convinced that it is the business of the true philosopher to avoid them altogether. It is more laborious to accumulate facts than to reason concerning; but one good experiment is of more value than the ingenuity of a brain like Newton's.'
In the same notebook, and at about the same time, alluding to his essays, he says: 'I was perhaps wrong in publishing, with such haste, a new theory of chemistry. My mind was ardent and enthusiastic. I believed that I had discovered the truth. Since that time my knowledge of facts is increased—since that time I have become more sceptical.'
He never forgot the lesson thus learned, and in after years its effects were shown in his unwillingness to advance a hypothesis with regard to any of his investigations.
Davy's residence at Clifton seems to have been (in every respect) fortunate. To his mother he writes: 'We are going on gloriously; our patients are getting better; and, to be a little conceited, I am making discoveries every day.' In a letter to Gilbert (April 10, 1799) he describes some recent experiments with vegetable tissues (reeds, corn, and grasses) to prove the existence of silex in epidermis, which experiments he had been led to make by the observation of one of the children that two bonnet-canes rubbed together in the dark produced a luminous appearance. But the most interesting and important part of this letter is that dealing with his experiments in the respiration of nitrous oxide gas (one of the gaseous compounds discovered by Priestley in 1776). After saying that they had now begun to investigate the effects of the gases in respiration, he goes on: 'I made a discovery yesterday which proves how necessary it is to repeat experiments. The gaseous oxide of azote (the laughing gas) is perfectly respirable when pure. It is never deleterious but when it contains nitrous gas. I have found a means of obtaining it pure.' He then relates that in order to test this fact he breathed sixteen quarts of the gas for nearly seven minutes, and that it 'absolutely intoxicated me'. It made him 'dance about the laboratory like a madman, and has kept my spirits in a glow ever since'.
During this year (1799) he published a full account of his experiments in Researches, Chemical and Philosophical, chiefly concerning Nitrous Oxide and its Respiration. In the concluding portion of his paper he hinted at the probable utility of nitrous oxide in surgical operations. Public attention was at once drawn to these Researches by reason of the novel and striking facts and discoveries which they contained, and Davy at twenty-one, on paying his first visit to London in December, 1799, found that his fame had preceded him in the capital, and that the circle of his friends and well-wishers had considerably enlarged.
When once the respirability of nitrous oxide gas was established patients were eager to try its effects. Southey, Coleridge, Tobin (the dramatist), Joseph Priestley (son of the famous chemist), the Wedgewoods, and others, were induced to breathe the gas and to record their sensations. The taking of laughing-gas became almost a fashion—greatly to the profit of Beddoes and his Institution—and a French writer, M. Fiévée, in his Lettres sur l'Angleterre (1802), whimsically introduced it into the catalogue of follies to which the English were addicted, and said that the practice amounted to a national vice.
In a letter to Gilbert, written some time during the summer of 1800, Davy says that he has been 'repeating the galvanic experiments with success', in the intervals of experiments on the gases, which 'almost incessantly occupied him from January to April.' 'Galvanism,' he says, 'I have found by numerous experiments to be a process purely chemical, and to depend wholly on the oxidation of metallic surfaces, having different degrees of electric conducting power.' 'Galvanism' was the term used for electricity. Volta's discovery of the electric pile, to which his name was afterwards attached, had just been announced in England, and philosophers were eagerly discussing its merits and possibilities and repeating the experiments performed by the famous Italian.
We come now to the period when Davy made his 'grand move' in life. The first intimation of this step is contained in the following letter to his mother, dated January 31, 1801:—
'My dear Mother,—During the last three weeks I have been very much occupied by business of a serious nature. This has prevented me from 130 writing to you, to my Aunt, and to Kitty. I now catch a few moments only of leisure to inform you that I am exceedingly well, and that I have had proposals of a very flattering nature to induce me to leave the Pneumatic Institution for a permanent establishment in London.
'You have perhaps heard of the Royal Philosophical Institution, established by Count Rumford, and others of the aristocracy. It is a very splendid establishment, and wants only a combination of talents to render it eminently useful.
'Count Rumford has made proposals to me to settle myself there, with the present appointment of assistant lecturer on chemistry, and experimenter to the Institute; but this is only to prepare the way for my being in a short time sole professor of chemistry, &c.; an appointment as honourable as any scientific appointment in the kingdom, with an income of at least £500 a year.
'I write to-day to get the specific terms of the present appointment, when I shall determine whether I shall accept it or not. Dr. Beddoes has honourably absolved me from all engagements at the Pneumatic Institution, provided I choose to quit it. However, I have views here which I am loath to leave, unless for very great advantages.
'You will all, I daresay, be glad to see me getting amongst the Royalists, but I will accept of no appointment except upon the sacred terms of independence.
'I am your most affectionate Son,
In the middle of February he went to London, whence he wrote that he was negotiating with Rumford, adding: 'His proposals have not been unfair; and I have nearly settled the business.'
Six weeks later (on April 25) he gave his first public lecture; three courses of lectures were delivered by Davy during the spring, and he seems to have given satisfactory proof of his abilities to the managers. In June Dr. Garnett, the first professor of chemistry, resigned his position through ill-health, and was succeeded by Dr. Young. In the same month Davy made his first communication to the Royal Society; the paper, which was called 'An account of some Galvanic Combinations, formed by an arrangement of single metallic plates and fluids, analogous to the Galvanic Apparatus of M. Volta', being read on June 18. In July the managers, following out the object of the Institution in assisting the industries, resolved that a course of lectures on the chemical principles of the Art of Tanning should be given by Davy, to begin in November. At the same time it was decided that Davy should have permission to absent himself during July, August, and September, 'for the purposes of making himself more particularly acquainted with the practical part of the business of tanning.'
Davy seized the opportunity of the interval to visit his home and to make a tour of the Cornish coast in the company of a friend named Underwood; in connection with this tour, Underwood (according to Paris) related that on one occasion, having bought a fine large bass, they took the fish to an inn and directed that it should be cooked for dinner. While waiting in the parlour Underwood missed Davy, and presently heard a great noise and commotion proceeding from the kitchen. On going to ascertain the cause he encountered the philosopher in full flight, pursued by the landlady, uttering irate cries and brandishing the frying-pan. It seems that Davy, presuming upon his knowledge of the manner in which a fish should be dressed, had invaded the kitchen and proffered his assistance in making the sauce and stuffing—to the indignation of the hostess, who had driven him away in a rage.
Davy's work at the Royal Institution comprised analyses of rocks and minerals, and in 1802 he was requested to take up the subject of Agricultural Chemistry with a view to giving practical advice to the farmers on various points connected with the treatment of soils and the growth of crops. In order that his investigations might obtain publicity through the proper channels, it was arranged that he should deliver a course of lectures on the subject at the Board of Agriculture, the department recently established by Sir John Sinclair. At that date the application of science to agriculture had hardly made a beginning; farmers knew nothing about the chemistry of farming, and hence could do very little towards improving the soils or perfecting the methods of cultivation. Information on these subjects was badly needed, and Davy's lectures may be said to have been the first effort to bring the department into practical touch with the farming community of England.
Davy realized the importance of the subject and entered with thoroughness into the work of preparation for his lectures, which obtained a popularity at this period scarcely to be imagined. Men of the first rank and talent, the literary and the scientific, the practical, the theoretical, blue stockings, and women of fashion, the old, the young, all crowded, eagerly crowded, lecture-room.
In 1803 Davy was appointed Chemical Professor to the Board of Agriculture. This was a year of honours, for in July the engagement of Arthur Young terminated, and Davy received the style of Professor of Chemistry at the Royal Institution. On February 24 he read before the Royal Society his first paper—on 'Astringent Vegetables, and their Operation in Tanning'. He was proposed a Fellow on April 21 and elected November 17. To complete the record, on July 7 he was elected an honorary member of the Dublin Society; from these events we pass to the year 1807, in which Davy made his brilliant discoveries with reference to the compound nature of the bodies called the 'fixed alkalis'. It appears that as far back as 1800—the year of the discovery of the voltaic pile—Davy had entertained the opinion that chemical combination might be due to the attraction of oppositely electrified substances. With this idea present in his mind he now sought to utilize the power with the invention of the voltaic pile had placed in his grasp to effect the decomposition of the fixed alkalis, potash and soda. His earliest experiments were made with single batteries of small power, and these were without result, but on the 19th of the same month he delivered before the Royal Society his memorable Bakerian lecture—'On some new Phenomera of Chemical Changes produced by Electricity, particularly the Decomposition of the fixed Alkalis, and the exhibition of the new substances which constitute their bases; and on the general Nature of Alkaline Bodies.'
The new metals were named by Davy Potassium and Sodium. In appearance potassium resembled quicksilver, but its metallic lustre was at once destroyed by exposure to the air, and by the absorption of oxygen and moisture the metal was re-converted into potash. Sodium likewise resembled silver, and like potassium quickly altered on exposure to the air. Owing to the fact there was considerable difficulty in preserving the metallic substances, but Davy eventually found that they could be preserved in naphtha.
The discovery of the metallic bases of potash and soda was completed within a very short space of time—between October 16 and 19, according to Paris. Dr. Davy speaks of 'the extreme delight which he [Davy] felt when he first saw the metallic basis of potash.' 'I have been told [he says] by Mr. Edmund Davy [his cousin and assistant] that when he saw the minute globules of potassium burst through the crust of potash, and take fire as they entered the atmosphere, he could not contain his joy—he actually danced about the room in ecstatic delight,' and it was some time before he was sufficiently composed to continue the experiment.
The feverish excitement under which Davy had laboured during these experiments—the results of which were put together with almost incredible speed—coupled with his low condition of health at the time,
It was not till the middle of March that he was able to resume his lectures, and of his aims as well as of his activity at this period we may judge from the following extract from a letter to his mother (August, 1809): 'At present, except when I resolve to idle for health's sake, I devote every moment to labours which I hope will not be wholly ineffectual in benefiting society, and which will not be wholly inglorious for my country hereafter; and the feeling of this is the reward which will continue to keep me employed.' Twelve months after the publication of his first Bakerian lecture Davy received the intelligence that the prize of 3,000 francs, established by Napoleon for the best experience made on the galvanic fluid, had been awarded to him by the Institute of France, 'for his discoveries announced in the Philosphical Transactions for the year 1807.'
In 1810 Davy was invited by the Dublin Society to give a course of lectures in that city on his recent discoveries in electro-chemical science. The invitation was accepted; Davy lectured to crowded audiences, and received for his fee sum of 500 guineas.
On April 8, 1812, he was knighted by the Prince Regent, and on the following day he delivered his farewell lecture as Professor of Chemistry at the Royal Institution. Michael Faraday (not yet engaged as assistant in the laboratory) was present on this occasion, on the look-out for the characteristics of a lecturer, and made the following entry in his notebook concerning Davy's style: 'During the whole of these observations his delivery was easy, his diction elegant, his tone good, and his sentiments sublime.' Another event closely concerning his happiness was impending—he was engaged to be married to Mrs. Apreece, widow of Mr. Shuckburgh Ashby Apreece, eldest son of Sir Thomas Apreece; she was the daughter and heiress of Charles Kerr of Kelso, and a distant connection of Sir Walter Scott.
He was married on April 11, 1812, and shortly after this event he writes to his brother concerning his position at the Royal Institution: —
'I was appointed Professor (honorary) to the Institution at the last meeting,' he writes on April 10, 1813. 'I do not pledge myself to give lectures. . . If I lecture it will be on some new discoveries, should it be my fortune to make them; and I give up the routine of lecturing, merely that I may have more time to pursue original inquiries, and forward more the great objects of science. This has been for some time my intention, and it has been hastened by my marriage. . . .'
The minutes of the Royal Institution record that on April 5, 1813, Davy begged leave to resign his situation of Professor of Chemistry, when Earl Spencer moved—'That, in order more strongly to mark the high sense entertained by this meeting of the merits of Sir H. Davy, he be elected honorary Professor of Chemistry.'
The working of our coal-mines during the early years of the last century was attended by what was then a new and special danger: this danger consisted in the liability of the gases of the mine to explode, or 'fire', on coming into contact with the naked candles carried by the miners; and on November 9 Davy, having visited the Newcastle district, read a paper on the subject before the Royal Society: 'On the Fire-damp of Coal-mines, and on methods of lighting the mine so as to prevent its explosion.' In this paper he describes the results of his experiments and confirms the opinion of other chemists that fire-damp is light carburetted hydrogen gas, and hence analogous to the inflammable gas of marshes. He establishes the following important points with regard to the inflammability of the gas: —(1) That it required to be mixed with a large proportion of ordinary air to produce an explosion. (2) That the heat required to cause an explosion was far greater than that required to explode other inflammable gases; thus, fire-damp could not be exploded by red-hot charcoal or red-hot iron. (3) That the heat produced by its explosion being less than that produced by any other inflammable gas the expansive effect from heat attending its explosion was also less. (4) That the mixture could not be fired in tubes of less than a certain diameter.
'In comparing,' says Davy, 'the power of tubes of metal and those of glass, it appeared that the flame passed more readily through glass tubes of the same diameter; and that explosions were stopped by metallic tubes of one-fifth of an inch when they were an inch and a half long; and this phenomenon probably depends upon the heat lost during the explosion in contact with so great a cooling surface, which brings the temperature of the first portions exploded below that required for the firing of the other portions. Metal is a better conductor of heat than glass; and it has been already shown that fire-damp requires a very strong heat for its inflammation.
Davy's first lamps were formed with small tubes for supplying air to the flame, but as he soon found that the metallic tubes represented by the meshes of wire gauze resisted equally well the passage of flame, he was led to surround the flame of the lamp with a cylinder of wire gauze. The gas readily passed through the meshes of the gauze and was consumed within it, filling the cylinder with a bright flame; but the explosion could not pass outwards, even although the wire became red-hot.
Thus Davy perfected a lamp which was successful because it captured the demon gas and destroyed it safely, or allowed it to explode itself harmlessly—the gas in the act of its explosion affording the light which the miner needed for his work, and some months later he was taken down into the pit and saw his lamp in actual use. He was urged to patent his invention, but refused, though by its universal adoption he might have secured a considerable fortune. 'I never thought of such a think,' was his reply; 'my sole object was to serve the cause of humanity; and if I have succeeded, I am amply rewarded in the gratifying reflection of having done so.'
In 1816 the Royal Society awarded him their Rumford Medal for his work in connection with the safety lamp and flame.
In October, 1818, Davy was made a baronet. Earlier in the same year he went to Naples at the instance of the Prince Regent to unfold and render legible the ancient papyri deposited in the museum of that city. He spent some time travelling on the Continent and returned to England early in 1820.
On the death of Sir Joseph Banks in June, 1820, Davy was elected to succeed him in the Presidential chair of the Royal Society. It was Sir Joseph's desire that Dr. Wollaston should be nominated his successor—he thought Davy 'rather too lively to fill the chair of the Royal Society with that degree of gravity which it is most becoming to assume'. Wollaston, however, declined to be nominated; and Davy, for his part, realized that 'the President's chair, after Sir Joseph, will be no light matter'. The voting was almost unanimous in his favour, and his popularity is shown by the fact that he was re-elected seven years in succession before his health compelled him to resign. He invariably took the chair in full Court dress, with the mace of office in front of him. He is thus depicted in the picture hanging in the rooms of the Royal Society.
The story of Davy's last years must be briefly told. In September, 1826, his mother died at an advanced age, having lived to witness her son's attainment to the highest position which it was in the power of science to bestow upon her votaries. Towards the end of the same year Davy had a slight apoplectic seizure. Though he recovered from the attack some paralysis remained, and he decided to spend the winter in Italy. He resigned the Presidentship in July, 1827, and in October returned to England. Shortly afterwards he published his Salmonia, or Days of Fly-fishing, a pleasant book, founded upon the model of Walton's famous work. In the spring of 1828 he quitted England for the last time, in the company of his brother John. The latter's duties as Army surgeon, however, called him away, and Humphry was left alone. On February 6, 1829, he writes to his friend Thomas Poole, from Rome: 'Would I were better . . . but I am here wearing away the winter, a ruin amongst ruins.' It was whilst meditating amidst the ruins of the Forum that he planned and wrote his last book, Consolations in Travel; or, The Last Days of a Philosopher, which was published after his death.
Davy died at Geneva on May 29, 1829, in the fifty-first year of his age, and was buried in the cemetery of Plain-Palais. A tablet to his memory was placed by his widow in the transept of Westminster Abbey, and later on a statue of Davy was erected in Market Jew Street, Penzance, the scene of his boyish exploits in story-telling.