Davy, Humphary

(b. Penzance, England, 17 December 1778; d. Geneva, Switzerland, 29 May 1829)

chemistry.

Humphry Davy was the eldest son of Robert and Grace Millett Davy. His father, of yeoman stock, was a woodcarver but earned little by it and lost money through speculations in farming and tin mining. After his death in 1794 Grace Davy managed a milliner’s shop until she inherited a small estate in 1799. After haphazard schooling Davy was apprenticed in 1795 to Bingham Borlase, an able apothecary-surgeon who later qualified as a physician. His scientific career began in 1798, when he was released from his indentures and was appointed superintendent of Thomas Beddoes’ Pneumatic Institution at Clifton. He retained a firm, and on occasion fervent, belief in a Supreme Being but does not seem to have been a zealous member of any church. In 1812 he married a wealthy bluestocking widow, Jane Apreece, but the marriage was childless and not happy. In the same year he was knighted and in 1818 was made a baronet. His health was good, aside from a serious illness, probably typhus, at the end of 1807; but in 1826 he suffered a stroke from which he never fully recovered. Most of Davy’s working life was spent at the Royal Institution in London; he was elected a fellow of the Royal Society in 1803 and was its president from 1820 to 1827. He was a foreign member of many societies overseas and was acquainted with many Continental scientists.

Davy said of his schooling that he was glad he had not been worked too hard and had been allowed time to think for himself. Schools in Cornwall in the late eighteenth century were not very good, but Davy emerged at fifteen with a fair knowledge of the classics. At about the same time that he began his apprenticeship he drew up a formidable program of self-education, which included theology and geography, seven languages, and a number of science subjects. He read a good deal of philosophy: Locke, Berkeley, Hume, Hartley, Thomas Reid, Condorcet, and even, according to his brother, some transcendentalist writings; and he began to write poetry. Toward the end of 1797 he began the study of chemistry with William Nicholson’s Dictionary of Chemistry and A. L. Lavoisier’s Traité élémentaire de chimie, which he read in French. He was fortunate that at this time Gregory Watt, the son of James Watt, lodged with the Davy family, having been advised to spend the winter in a mild climate on account of his health. After Gregory Watt’s departure, he and Davy maintained a correspondence. Also during this period Davy became acquainted with Davies Giddy, who later changed his surname to Gilbert and succeeded Davy as President of the Royal Society. Giddy allowed Davy to use his books and helped in the negotiations that led to his going to Clifton. Borlase had quite a good library, and Davy also had access to that of the Tonkins, who were friends of the family.

With this basis of wide but rather undirected reading, Davy began his career as a chemist; and within five years of reading his first chemistry book he had become professor of chemistry at the Royal Institution. His first research, culminating in speculative papers on the role of light, was directed to proving wrong Lavoisier’s doctrine of caloric. Lavoisier had placed light and heat, or caloric, at the head of his table of simple bodies and had asked rhetorically whether heat was a modification of light, or vice versa. He believed that caloric combined with other substances and, in particular, that oxygen gas was a compound of a substance or “basis” (so far unknown) and heat. Davy, in a tradition stemming from Newton’s Opticks, believed that heat was motion but that light was matter. He considered oxygen gas a compound not of oxygen and caloric (for there was no such substance), but of oxygen and light; and he suggested that it be called “phosoxygen.”

Davy performed various experiments in support of his hypothesis, of which the most famous was the ice-rubbing experiment of melting ice by friction to prove the kinetic theory of heat. He took precautions against heat flowing into the system from outside, but these apparently were inadequate; there is considerable doubt as to whether Davy could have observed the effects he described. This work was independent of the more quantitative contemporary studies of Benjamin Thompson (Count Rumford). Davy sparked gunlocks in vacuo to see if light was emitted in the absence of oxygen and satisfied himself that it was not, even though heat was generated. Light could not, therefore, be a modification of heat. Sir Harold Hartley has cleared up the problem of how Davy obtained the apparatus for these experiments, by uncovering evidence of his friendship with Robert Dunkin, an instrument maker.

Davy wrote up his researches as “An Essay on Heat, Light, and the Combinations of Light.” Beddoes declared himself a convert to Davy’s views and published the essay in 1799, in a collection entitled Contributions to Physical and Medical Knowledge, Principally From the West of England. Davy later repudiated the essay (Nicholson’s Journal of Natural Philosophy, Chemistry and the Arts, 3 [1799–1800], 517), but the work is valuable for the light it casts on the working of his mind and for the new observations it contains. Joseph Priestley, among others, was impressed. In place of the theory-loaded term “caloric” Davy proposed “repulsive motion,” a phrase that William Thomson later praised for its suggestiveness. In solids, attractive motions exceeded repulsive ones; in fluids the two were balanced; and in gases the repulsive motions exceeded the attractive. Light was another state in which the repulsive motion far exceeded the attractive, and the particles were therefore projected at great speed. This passage foreshadows the idea of a fourth state of matter that is found in the writings of Michael Faraday and the work of William Crookes, who believed the cathode rays to be such a state. Davy’s light particles were little affected by gravity and did not contribute perceptible mechanical motion, although they did communicate repulsive motion.

Davy believed that the theory of caloric fluid had been proposed to explain the expansion of bodies with heat, “in conformity to the absurd axiom, bodies cannot act where they are not”; but this was to solve a small difficulty by creating a great one. Change of state should not be identified with combination with caloric, for nothing corresponding to chemical change occurred; the quantity of repulsive motion increased, but that was all. Bodies in different states were not compounds with more or less caloric—hydrogen and nitrogen were probably gaseous metals—and it was therefore as inappropriate to talk with the French nomenclators of “hydrogen gas” as it would be to speak of “solid gold.” Thus “hydrogen” alone would be the proper term; but oxygen gas was different because it was a compound body containing light, and therefore it should be called “phosoxygen.”

Davy was impressed by the importance of light and wrote that the planetary motions seemed to have been designed expressly to supply the solar system with the necessary quantity of light, and that light within and without us was the source of perception, thought, and happiness. He believed that the laws of refraction represented the laws of attraction of diaphanous bodies for light and that the different colors corresponded to different repulsive motions in the light particles. Since the red particles vibrated fastest, they were least attracted by the particles of bodies. Dark bodies contained less light than pale ones. In a passage suppressed in the final text—but referred to elsewhere in the paper—he suggested that electricity might be condensed light, given off at the poles as auroras, and that the phenomena of the mutations of matter probably all arose from the interconversions of the gravitative, mechanical, and repulsive motions. The blue color of air showed that the repulsive motion of light was diminished in passing through it. Phosphorescent bodies contained loosely combined light, whereas in phosoxygen the combination was intimate. In recapitulation, Davy declared that repulsive and attractive motions were the causes of effects uniformly and constantly produced, whereas caloric was imaginary.

As Davy moved into the biological realm, his speculations became more extreme; but he demonstrated photosynthesis in marine vegetation, and he showed the presence of carbon dioxide in venous blood. He wrote that nature had catenated all organic beings, making them mutually dependent and all dependent upon light, and that chemistry, through its connections with the laws of life, promised to become the most sublime and important of the sciences, bringing about the destruction of pain and the increase of pleasure.

In this essay Davy makes rhetorical, but suggestive, cosmological remarks: he attacks Lavoisier for introducing imaginary substances and a theory-loaded nomenclature; appeals to a Newtonian theory of heat, light, and matter; and indulges in speculations concerning light not uncharacteristic of those influenced by the Romantic movement. In his later work Davy kept these strands apart, so that the speculative and cosmological material appeared in his lectures and in his last works, Salmonia and Consolations in Travel, and in his poetry; in his papers in the Philosophical Transactions of the Royal Society, he sought to appear as a Newtonian, using the notion of vera causa to demolish “the principle of acidity” as he had used it to expel caloric. Coleridge and Southey praised Davy’s poetry and his style of lecturing; it is hard today to work up much enthusiasm for his verses, but his prose works are still pleasing.

Davy met Coleridge and Southey at Clifton, for Beddoes had married an Edgeworth and moved in literary society; and he maintained a correspondence with both poets for some years. He also began a lifelong friendship with Thomas Poole, of Nether Stowey. The object of Beddoes’ Pneumatic Institution was to investigate the possibility of using “factitious airs” (synthetic gases) in the cure and prevention of disease; in the course of his researches Davy tried breathing nitrous oxide and discovered its anesthetic properties. Samuel Mitchill, an American, had suggested that this gas was the principle of contagion, which must prove instantly fatal to anyone who respired it. Davy was not convinced by Mitchill’s arguments and therefore made the experiment. He suggested that the gas might be employed in minor surgical operations, but nobody took any notice of this recommendation. Instead, breathing nitrous oxide for the delightful feeling of intoxication became the rage; and Davy, in his book on nitrous oxide and its respiration, published in 1800, gave a series of subjective accounts of nitrous oxide anesthesia, which are among the best on record. But experiments at the Pneumatic Institution failed to reveal any great efficacy of nitrous oxide in curing disease. Davy proceeded to try other gases, including nitric oxide and carbon monoxide; he later warned his brother against perilous experiments of this kind.

Davy’s book on nitrous oxide included chemical analyses of the oxides of nitrogen and studies of their reactions. In these, as in his later researches, Davy showed his great facility for qualitative experiment; on the quantitative side, his volumetric analyses were quite good, and he tended afterward to prefer volumetric analyses to more accurate gravimetric methods. Indeed, his laboratory work was characterized by bursts of intense labor, in which he attained his results with great rapidity and showed great ability in adapting existing apparatus to new functions. The accurate and painstaking analyses of Berzelius would not have been possible to one with Davy’s temperament; in addition, he lacked formal training and, more important, he always wanted to be original and creative. To review, repeat, or confirm the findings of his contemporaries was much less congenial to him than to press on to new discoveries.

The book on nitrous oxide, which made Davy’s reputation, is among his best productions, containing systematic and sustained argument supported by quantitative data. While the researches upon which the book is based were still in progress, Volta’s invention of the pile was announced; and before Volta’s paper appeared in print, Nicholson and A. Carlisle reported that they had used such a pile to decompose water into oxygen and hydrogen. Davy at once rushed into this new field and published a number of papers on the subject in Nicholson’s Journal of Natural Philosophy, Chemistry and the Arts in the latter part of 1800. Of all those who worked on the pile, Davy consistently showed himself the clearest-headed. He appears to have realized from the first that the “contact theory”—that electricity was generated by the mere contact of dissimilar metals—was inadequate and that the production of electricity depended upon a chemical reaction’s taking place. And in electrolytic cells he remained convinced—and ultimately proved—that the current acted to separate compounds into their components, rather than to synthesize new substances; the latter view enjoyed support in both France and Germany.

Davy found that the pile could not operate if the water between the plates contained no oxygen, and he concluded that the oxidation of the zinc was the cause of the generation of electricity. In accordance with this, he found that nitric acid in the pile was extremely—indeed alarmingly—effective. He established that a battery could be made with poles of charcoal and zinc and also with two fluids and one metallic component, provided one of the fluids would attack the metal. Shortly afterward he invented the carbon arc. He also employed cells in which the poles were in separate vessels connected by moist filaments of amianthus, a woven asbestos fiber.

These researches were interrupted in 1801, when Davy was appointed to a lectureship at the Royal Institution; in the following year he was promoted to professor of chemistry. The Royal Institution had been founded by Rumford, Thomas Bernard, and others largely to provide technical training; but Davy’s predecessor, Thomas Garnett, had begun to attract large and fashionable audiences to lectures on science. Under Davy this trend grew stronger, until the Royal Institution became a center for advanced research and for polished demonstration lectures. From the start Davy succeeded in holding large audiences, which Garnett and Thomas Young had begun to lose; they increased until about 1810, when approximately 1,000 people flocked to hear him. The lectures kept the Royal Institution on a tolerably firm financial footing, but Davy seems to have regarded them as an interruption of the research program. Certainly his audiences were able to hear accounts of researches actually in progress and, in particular, to see the latest discoveries in electrochemistry demonstrated before their eyes.

In his first years at the Royal Institution, Davy was set to lecture on a number of technical subjects, and he published a long article on tanning; for this and his other papers he was awarded the Copley Medal in 1805. He gave lectures on a range of sciences and claimed to have given the first public course on geology in London. In 1802 he lectured before the Board of Agriculture on agricultural chemistry; this course was repeated each year until 1812 and was published in 1813. This was the first serious attempt to apply chemistry to agriculture, and it remained a standard work until displaced by Justus von Liebig’s publications a generation later. The book is of interest because of its pioneering nature, and it went through a number of editions; but its value must be said to lie more in the impulse it gave toward the application of scientific methods in agriculture than in any of the theories advanced. Through these lectures Davy became acquainted with various great landowners and attended such functions as the sheepshearing at Woburn.

In 1806 Davy was able to return to electrochemistry, and in November of that year it formed the subject of the Bakerian Lecture, which he delivered before the Royal Society. The first part of the lecture was concerned with the decomposition of water on electrolysis. In 1800 Davy had concluded that oxygen and hydrogen, in the theoretical proportions, were the only products of the electrolysis of pure water; and Berzelius and Hisinger had come to the same conclusion. But other workers had remarked on the presence of acid and alkali around the poles and had noticed that the theoretical yields of oxygen and hydrogen were not attained. Davy established that when pure water, redistilled in silver apparatus, was electrolyzed in gold or agate vessels in an atmosphere of hydrogen (so that nitrogen could not combine with the nascent hydrogen or oxygen), it was decomposed into oxygen and hydrogen only.

In the six years since the experiment of Nicholson and Carlisle, nobody had reasoned and experimented with a clarity approaching this. Davy then proceeded to discuss the use of electrolysis as a method of chemical analysis and the transport of substances during electrolysis, and to propose an electrical theory of chemical affinity. He found that if three vessels connected by filaments were used, with the poles in the outer pair, a neutral salt solution in one of the outer cups, and turmeric or litmus in each vessel, then only near the poles were the indicators affected. But with barium chloride in an outer cup and sulfuric acid in the center one, a precipitate was formed in the center cup. Davy’s theory was very general, involving some kind of chain mechanism; Faraday was later able to list a dozen incompatible theories of electrolysis, all of which claimed to derive from Davy’s views. Davy found that the electrical condition of a substance can modify its chemical properties; negatively electrified zinc is inert, and positively electrified silver is reactive. This, and that an electric current decomposed compounds, led Davy to propose that chemical affinity is electrical. But it was not his nature to raise his discoveries into systems, which he considered prisons of the mind; and thus he left it to Berzelius to develop the system of dualism from this insight. In “dualism.” chemical elements were viewed as electrically positive or negative; they combined to form neutral products, which could be polarized and decomposed by an electric current.

In this lecture Davy did not announce any very important analyses, but in the Bakerian Lecture of 1807 he was able to describe the isolation of potassium and sodium. In 1806 he had remarked that the new methods of investigation promised to lead to a more intimate knowledge of the true elements of bodies. Lavoisier, while laying down the principle that the chemist was concerned not with elements but with those bodies which could not be decomposed, had nevertheless (inconsistently) refused to put the alkalies, soda and potash, on his list of undecomposed substances because of their analogies with ammonia. Davy found that if aqueous solutions of the alkalies were electrolyzed, only the water was decomposed. Dry potash did not conduct; but when, in October 1807, he employed slightly damp fused potash, he found that globules of silvery matter collected at the negative pole. Most of these caught fire, but some could be collected. At the positive pole pure oxygen was liberated. Davy danced about the room in ecstatic delight; he likened the potassium to substances imagined by alchemical visionaries. Because his potassium was impure, containing sodium, it was fluid at room temperature; and its extreme lightness also made it perplexing to classify. Davy at first called it “potagen” but within a short time of the discovery he had decided that “the analogy between the greater number of properties must always be the foundation of arrangement,” and he therefore called it “potasium” (sic), a name implying metallic status. By the time he delivered the Bakerian Lecture in November, Davy was able to announce many of the properties of sodium and potassium.

Lavoisier’s remarks must have guided Davy in choosing the alkalies to investigate; and after his triumph Davy analyzed the alkaline earths, isolating magnesium, calcium, strontium, and barium; he then obtained boron and silicon. But his discovery that the alkalies were oxides was a puzzle. For Lavoisier oxygen was the principle of acidity; Davy had shown that with equal justice it might be called the principle of alkalinity. His work during the next four years or so was to establish that chemical elements do not behave as “principles” of this kind; he concluded that chemical properties were a function not simply of the components of a substance but also of their relative arrangements. Thus he finally put it beyond doubt that carbon and diamond were chemically identical; that neither all acids nor all alkalies contained oxygen; and that oxygen enjoyed no unique status as the supporter of combustion, but rather that heat was a consequence of any violent chemical change.

The Bakerian Lectures of 1808 and 1809 (Davy was called upon to deliver five of these lectures in succession) show him floundering as he tried one hypothesis after another to account for the ultimate constitution of matter and for the nature of acidity. He believed that the simplicity and harmony of nature demanded that there be very few ultimately distinct forms of matter; it is ironical that one who held that the chemical elements were probably all compounds should have been such a frequent discoverer of new elements. Davy was particularly confused by ammonium amalgam, a pasty material produced when ammonium salts are electrolyzed with a mercury cathode. For Davy and his contempories this proved the metallic nature of “ammonium” and made the compound nature of potassium and sodium, or the metallic nature of nitrogen or hydrogen, almost certain. Davy made the “phlogistic” conjecture that all metals might contain hydrogen, although at the same time he established that experiments of Gay-Lussac and Thenard, which purported to show that potassium was a compound of potash and hydrogen, were misleading.

A change came over Davy’s work in 1809, when he embraced the doctrine of definite proportions; however, he never accepted John Dalton’s atomic theory, believing it to be speculative. The nearest he came to a definite theory of matter was in a dialogue unfinished at his death, in which he adopted a quasi-Boscovichean atomism; but Davy was not the man to adhere to any theoretical system, believing, as he often wrote, that the only value of hypotheses was that they led to new experiments.

Work on tellurium established that hydrogen telluride, containing no oxygen, was an acid; Davy’s first reaction was that hydrogen might be an oxide. But in 1810 the road at last opened in front of him again, and he realized that oxygen was not a constituent of all acids. Muriatic acid, our hydrochloric acid, was the critical case. Lavoisier had declared that it must be an oxide of an unknown substance or “basis,” and oxymuriatic acid, our chlorine, a higher oxide. All attempts to extract the “basis” had failed; Davy found that white-hot charcoal extracted no oxygen from oxymuriatic acid and that when tin reacted with the gas and ammonia was added, no oxide of tin was formed. Further, when oxymuriatic acid and ammonia reacted, if both were dry, no water was formed; and when the solid compound of this gas and phosphorus was treated with ammonia, no phosphoric acid was obtained.

Gay-Lussac and Thenard had simultaneously been experimenting on this subject and had concluded that it would be possible to argue for the elementary nature of oxymuriatic acid; but they resisted Davy’s arguments when he put them forward. He declared that oxygen was never produced in reactions in which oxymuriatic acid was concerned unless water was present, and concluded that no substance had a better claim to be regarded as undecomposed. Applying Lavoisier’s criterion more rigidly than Lavoisier, he placed oxymuriatic acid among the elements as an analog of oxygen and gave it the theory-free name “chlorine.” With the demolition of the scaffolding of the oxygen theory of acids, the view that all exothermic reactions were oxidations, and the caloric theory, Lavoisier’s revolution was complete; and Davy’s chemical career, to all intents and purposes, was over.

In 1812 he published part I of Elements of Chemistry, containing a very readable account of that part of the field in which he had worked. Reviewers guessed that part II, which would cover the rest of the science, would never appear, and they were right; Davy could never have produced a systematic treatise. In April 1812, he had been knighted by the Prince Regent, and three days later he married Jane Apreece. In 1813, after receiving from Michael Faraday a fair copy of notes of some of his lectures on chlorine, he offered Faraday a post as laboratory assistant. When he set off for France in the autumn of 1813, to claim the medal established by Napoleon and awarded him by the Institut de France for his electrical discoveries, Faraday accompanied him as his assistant and also acted as his valet. England and France were at war, but Davy was well received by his French colleagues and was elected a corresponding member of the Institute. In a race with Gay-Lussac he elucidated the nature of iodine, using a little case of apparatus he had brought with him, and determined its essential properties, anticipating his rival’s more detailed account.

On his return to England in 1815, Davy was asked to turn his attention to the explosions in coal mines, which had recently been the cause of a number of disasters. He visited Newcastle-on-Tyne in August 1815 and arranged for samples of the explosive gas firedamp to be sent to him at the Royal Institution. He confirmed that methane was the main constituent and independently confirmed the observations of Tennant and Wollaston that this gas could be ignited only at a high temperature. Because of this it will not communicate flame through a narrow tube of sufficient length; the cooling effect of the tube is too great. Davy constructed lamps in which the air intake and the chimney were composed of narrow tubes, and found that they did not explode firedamp. He then found that wire gauze was equally efficient; and the Davy lamp, in which the flame is surrounded by wire gauze, was born. The whole research occupied less than three months, and is an example of Davy at his best. It led to research on flame, in which he concluded that luminosity is due to the presence of solid particles. It is sad to have to record that explosions in coal mines did not decrease in number; but coal production rose dramatically in the first half of the nineteenth century as deeper and more dangerous pits could be worked.

Davy went abroad again in 1818 and attempted to unroll papyruses found at Herculaneum, using chlorine to decompose the gummy matter holding them together. In the summer of 1820 Davy heard of the illness of Sir Joseph Banks, who had become president of the Royal Society a few days before Davy was born; and he returned to London at once. Banks died, and it became clear that the main competitors for the chair would be Davy and W. H. Wollaston, who became acting president for the rest of the year. Davy was determined to win, and Wollaston withdrew before the election.

At this time the council of the Royal Society for the first time contained a majority of active scientists, and Davy hoped for greater endeavors from the fellows and for greater support of science from the government. In 1826 the Royal Medals were endowed by the king, but the government interest in science for which Davy had hoped did not materialize. He also hoped to convert the British Museum into a research institute rather like the Museum of Natural History in Paris; but again nothing came of this. The Royal Society was asked to look into the matter of the corrosion of the copper bottoms of ships, and Davy took this investigation upon himself. He found that if pieces of more electropositive metals, which he called “protectors,”. were fixed to the copper plates, the copper was not attacked by the seawater; unfortunately, in trials it appeared that marine organisms adhered so tenaciously to the protected copper that the performance of the ships was seriously affected, and the discovery was never taken up. The affair provided more ammunition for Davy’s enemies, who considered him arrogant and high-handed.

In this period there were rather inconclusive electrical experiments, following Oersted’s discovery of electromagnetic induction, and the experiments with Faraday on the liquefaction of gases in sealed tubes. A sad business was Davy’s opposition to Faraday’s he had been generous election as a fellow of the Royal Society in 1824, for he had been generous to Faraday and really liked him. The affair reveals Davy’s isolation and unhappiness. In 1826 he delivered his last Bakerian Lecture, adding very little of moment to those of 1806 and 1807.

Soon afterward Davy suffered his first stroke, and thereafter his life consisted of lonely journeys around Europe in search of health, fishing, and shooting. During this period he wrote a paper on volcanoes, based on observations of Vesuvius; Davy had always been interested in geology and, unlike Banks, had encouraged the Geological Society, and later other specialized societies, seeing their role as complementary to that of the Royal Society. He had suggested that volcanoes might have a core of alkali metal, acted on by water to cause eruption; but analyses of lava did not confirm this hypothesis, and he dropped it. It was Davy who persuaded R. I. Murchison to take up geology. Also from his last journeys came Salmonia and Consolations in Travel, dialogues in which Davy sought to communicate his world view; these went through many editions.

Students have disagreed over the extent to which Davy had a consistent philosophical position; he can be viewed simply as an opportunist, striking at weak points in Lavoisier’s chemistry. Others see in the early paper, lecturẹs, and Consolations evidence of a romantic outlook reflected in Davy’s friendships and perhaps exerting some influence upon his theorizing, particularly in his attitude toward the atomic theory. But the abiding impression gained from Davy’s scientific works is of great experimental facility and of a determination to separate hypotheses from facts as far as possible.

BIBLIOGRAPHY

Davy’s works were brought together as The Collected Works of Sir Humphry Davy, Bart., John Davy, ed., 9 vols. (London, 1839–1840). A new edition, with an introduction by R. Siegfried, is being prepared. A bibliography has been compiled by J. Z. Fullmer (Cambridge, Mass., 1969). At the Royal Institution there is a large collection of Davy’s MSS, including his notebooks. An edition of these is a desideratum.

Biographies of Davy are John Davy, Memoirs of the Life of Sir Humphrey Davy, Bart., (London, 1836); and Fragmentary Remains, Literary and Scientific, of Sir Humphry Davy (London, 1858); H. Hartley, Humphry Davy (London, 1967); and J. A. Paris, The Life of Sir Humphry Davy (London, 1831). J. Z. Fullmer is preparing a full-scale biography of Davy and an edition of his letters.

Recent articles on Davy include J. Z. Fullmer, “Humphry Davy’s Adversaries,” in Chymia, 6 (1960), 102–126; D. M. Knight, “The Scientist as Sage,” in Studies in Romanticism, 6 (1967), 65–88; W. D. Miles, “Sir Humphry Davie, the Prince of Agricultural Chemists,” in Chymia, 7 (1961), 126–134; C. A. Russell, “The Electrochemical Theory of Sir Humphry Davy,” in Annals of Science, 15 (1959), 1–25; 19 (1963), 255–271; and R. Siegfried, “Sir Humphry Davy on the Nature of the Diamond,” in Isis, 57 (1966), 325–335.

David M. Knight