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On October 2nd, 1798, Davy set out for Clifton with such books and apparatus as he possessed, and the MSS. of his essays on Heat and Light safely stowed away among his baggage. He was in the highest spirits, and full of confidence in the future. On his way through Okehampton he met the London coach decked with laurels and ribbons, and bringing the news of Nelson’s victory of the Nile, which he interpreted as a happy omen. A few days after his arrival, he thus wrote to his mother:—

“October 11th, 1798. Clifton.

“My dear Mother,—I have now a little leisure time, and I am about to employ it in the pleasing occupation of communicating to you an account of all the new and wonderful events that have happened to me since my departure.

“I suppose you received my letter, written in a great hurry last Sunday, informing you of my safe arrival and kind reception. I must now give you a more particular account of Clifton, the place of my residence, and of my new friends Dr. and Mrs. Beddoes and their family.

“Clifton is situated on the top of a hill, commanding a view of Bristol and its neighbourhood, conveniently elevated above the dirt and noise of the city. Here are houses, rocks, woods, town and country in one small spot; and beneath us, the sweetly-flowing Avon, so celebrated by the poets. Indeed there can hardly be a more beautiful spot; it almost rivals Penzance and the beauties of Mount’s Bay.

“Our house is capacious and handsome; my rooms are very large, nice and convenient; and, above all, I have an excellent laboratory. Now for the inhabitants, and, first, Dr. Beddoes, who, between you and me, is one of the most original men I ever saw—uncommonly short and fat, with little elegance of manners, and nothing characteristic externally of genius or science; extremely silent, and in a few words, a very bad companion. His behaviour to me, however, has been particularly handsome. He has paid me the highest compliments on my discoveries, and has, in fact, become a convert to my theory, which I little expected. He has given up to me the whole of the business of the Pneumatic Hospital, and has sent to the editor of the Monthly Magazine a letter, to be published in November, in which I have the honour to be mentioned in the highest terms. Mrs. Beddoes is the reverse of Dr. Beddoes—extremely cheerful, gay and witty; she is one of the most pleasing women I have ever met with. With a cultivated understanding and an excellent heart, she combines an uncommon simplicity of manners. We are already very great friends. She has taken me to see all the fine scenery about Clifton; for the Doctor, from his occupations and his bulk, is unable to walk much. In the house are two sons and a daughter of Mr. Lambton, very fine children, from five to thirteen years of age.

“I have visited Mr. Hare, one of the principal subscribers to the Pneumatic Hospital, who treated me with great politeness. I am now very much engaged in considering of the erection of the Pneumatic Hospital, and the mode of conducting it. I shall go down to Birmingham to see Mr. Watt and Mr. Keir in about a fortnight, where I shall probably remain a week or ten days; but before then you will again hear from me. We are just going to print at Cottle’s; in Bristol, so that my time will be much taken up the ensuing fortnight in preparations for the press. The theatre for lecturing is not yet open; but, if I can get a large room in Bristol, and subscribers, I intend to give a course of chemical lectures, as Dr. Beddoes seems much to wish it.

“My journey up was uncommonly pleasant; I had the good fortune to travel all the way with acquaintances. I came into Exeter in a most joyful time, the celebration of Nelson’s victory. The town was beautifully illuminated, and the inhabitants loyal and happy....

“It will give you pleasure when I inform you that all my expectations are answered and that my situation is just what I could wish. But, for all this, I very often think of Penzance and my friends, with a wish to be there; however that time will come. We are some time before we become accustomed to new modes of living and new acquaintances.

“Believe me, your affectionate son,

“Humphry Davy.”

Mrs. Beddoes, of whom Davy speaks in such appreciative terms, was one of the many sisters of Maria Edgeworth. She seems to have possessed much of the intelligence, wit, vivacity, and sunny humour of the accomplished authoress of “Castle Rackrent”; and, by her charm of manner and her many social gifts, to have made her husband’s house the centre of the literary and intellectual life of Clifton. Thanks to her influence, Davy had the good fortune to be brought into contact, at the very outset of his career, with Southey, Coleridge, the Tobins, Miss Edgeworth, and other notable literary men and women of his time, with many of whom he established firm and enduring friendships. He had always a sincere admiration for his fair patroness, and a grateful memory of her many acts of kindness to him at this period of his life. That she in turn had an esteem amounting to affection for the gifted youth is evident from the language of tender feeling and warm regard in which her letters to him are expressed. The sonnets accompanying these letters are couched in terms which admit of no doubt of the strength of her sentiments of sympathy and admiration, and some of the best efforts of his muse were addressed to her in return.

His work and prospects at the Pneumatic Institution are sufficiently indicated in the following letter to his friend and patron, Mr. Davies Gilbert, written five weeks after his arrival at Clifton:—

“Clifton, November 12, 1798.

“Dear Sir,—I have purposely delayed writing until I could communicate to you some intelligence of importance concerning the Pneumatic Institution. The speedy execution of the plan will, I think, interest you both as a subscriber and a friend to science and mankind. The present subscription is, we suppose nearly adequate to the purpose of investigating the medicinal powers of factitious airs; it still continues to increase, and we may hope for the ability of pursuing the investigation to its full extent. We are negotiating for a house in Dowrie Square, the proximity of which to Bristol, and its general situation and advantages, render it very suitable to the purpose. The funds will, I suppose, enable us to provide for eight or ten patients in the hospital, and for as many out of it as we can procure.

“We shall try the gases in every possible way. They may be condensed by pressure and rarefied by heat. Quere,—Would not a powerful injecting syringe furnished with two valves, one opening into an air-holder and the other into the breathing chamber, answer the purpose of compression better than any other apparatus? Can you not, from your extensive stores of philosophy, furnish us with some hints on this subject? May not the non-respirable gases furnish a class of different stimuli? of which the oxymuriatic acid gas [chlorine] would stand the highest, if we may judge from its effects on the lungs; then, probably, gaseous oxyd of azote [nitrous oxide?] and hydrocarbonate [the gases obtained by passing steam over red-hot charcoal].

“I suppose you have not heard of the discovery of the native sulphate of strontian in England. I shall perhaps surprise you by stating that we have it in large quantities here. It had long been mistaken for sulphate of barytes, till our friend Clayfield, on endeavouring to procure the muriate of barytes from it by decomposition, detected the strontian. We opened a fine vein of it about a fortnight ago at the Old Passage near the mouth of the Severn.B...

“We are printing in Bristol the first volume of the ‘West Country Collection,’ which will, I suppose, be out in the beginning of January.

“Mrs. Beddoes ... is as good, amiable, and elegant as when you saw her.

“Believe me, dear Sir, with affection and respect, truly yours,

“Humphry Davy.”

B Cf. An account of several veins of Sulphate of Strontites, found in the neighbourhood of Bristol, with an Analysis of the different varieties. By W. Clayfield. “Nicholson’s Journ.,” III., 1800, pp. 36–41.

The work alluded to in this letter made its appearance in the early part of 1799, under the title of “Contributions to Physical and Medical Knowledge, principally from the West of England; collected by Thomas Beddoes, M.D.” The first half of the volume, in accordance with the editor’s promise, is occupied by two essays from Davy: the first “On Heat, Light, and the Combinations of Light, with a new Theory of Respiration”; the second “On the Generation of Phosoxygen (Oxygen Gas), and on the Causes of the Colours of Organic Beings.”

To the student these essays have no other interest than is due to the fact that they are Davy’s first contribution to the literature of science. No beginning could be more inauspicious. It is the first step that costs, and Davy’s first step had well nigh cost him all that he lived for. As additions to knowledge they are worthless; indeed, a stern critic might with justice characterise them in much stronger language. Nowadays such writings would hopelessly damn the reputation of any young aspirant for scientific fame, for it is indeed difficult to believe, as we read paragraph after paragraph, that their author had any real conception of science, or that he was capable of understanding the need or appreciating the value of scientific evidence.

The essays are partly experimental, partly speculative, and the author apparently would have us believe that the speculations are entirely subservient to and dependent on the experiments. Precisely the opposite is the case. Davy’s work had its origin in Lavoisier’s “Traité Elémentaire,” almost the only text-book of chemistry he possessed. Lavoisier taught, in conformity with the doctrine of his time, that heat was a material substance, and that oxygen was essentially a compound body, composed of a simple substance associated with the matter of heat, or caloric. The young novitiate puts on his metaphysical shield and buckler; and with the same jaunty self-confidence that he assailed Locke and criticised Berkeley, enters the lists against this doctrine, determined, as he told Gregory Watt, “to demolish the French theory in half an hour.”

After a few high-sounding but somewhat disconnected introductory sentences, and a complimentary allusion to “the theories of a celebrated medical philosopher, Dr. Beddoes,” he proceeds to put Lavoisier’s question, “La lumière, est-elle une modification du calorique, ou bien le calorique est-il une modification de la lumière?” to the test of experiment. This he does by repeating Hawksbee’s old experiment of snapping a gunlock “armed with an excellent flint” in an exhausted receiver. The experiment fails in his hands; such phenomena as he observes he misinterprets, and he at once concludes that light and heat have nothing essentially in common. “Nor can light be as some philosophers suppose, a vibration of the imaginary fluid ether. For even granting the existence of this fluid it must be present in the exhausted receiver as well as in atmospheric air; and if light is a vibration of this fluid, generated by collision between flint and steel in atmospheric air, it should likewise be produced in the exhausted receiver, where a greater quantity of ether is present, which is not the case.” Since, then, it is neither an effect of caloric nor of an ethereal fluid, and “as the impulse of a material body on the organ of vision is essential to the generation of a sensation, light is consequently matter of a peculiar kind, capable when moving through space with the greatest velocity, of becoming the source of a numerous class of our sensations.”

By experiments, faultless in principle but wholly imperfect in execution, he next seeks to show that caloric, or the matter of heat, has no existence. His reasoning is clear, and his conceptions have the merit of ingenuity, but any real acquaintance with the conditions under which the experiments were made would have convinced him that the results were untrustworthy and equivocal; and yet, in spite of the dubious character of his observations, he arrived at a theory of the essential nature of heat which is in accord with our present convictions, and which he states in the following terms:—

“Heat, or that power which prevents the actual contact of the corpuscles of bodies, and which is the cause of our peculiar sensations of heat and cold, may be defined a peculiar motion, probably a vibration, of the corpuscles of bodies, tending to separate them.”

This conception of the nature of heat did not, of course, originate with him, and it was a question with his contemporaries how far he was influenced by Rumford’s work and teaching. On this point Dr. Beddoes’s testimony is direct and emphatic. He says:—

“The author [Davy] derived no assistance whatever from the Count’s ingenious labours. My first knowledge of him arose from a letter written in April 1798, containing an account of his researches on heat and light; and his first knowledge of Count Rumford’s paper was conveyed by my answer. The two Essays contain proofs enough of an original mind to make it credible that the simple and decisive experiments on heat were independently conceived. Nor is it necessary, in excuse or in praise of his system, to add, that, at the time it was formed, the author was under twenty years of age, pupil to a surgeon-apothecary, in the most remote town of Cornwall, with little access to philosophical books, and none at all to philosophical men.”

Having thus, with Beddoes, expunged caloric from his chemical system, Davy proceeds to elevate the matter of light into its place. According to Lavoisier oxygen gas was a compound of a simple substance and caloric; Davy seeks to show that it is a compound of a simple substance and light. He objects to the use of the word “gas,” since, according to French doctrine, it is to be taken as implying not merely a state of aggregation but a combination of caloric with another substance, and suggests therefore that what was called oxygen gas should henceforth be known as phosoxygen. His “proofs” that oxygen is really a compound of a simple substance with “matter in a peculiar state of existence” are perhaps the most futile that could be imagined. Charcoal, phosphorus, sulphur, hydrogen, and zinc were caused to burn in oxygen; light was evolved, oxides were formed, and a deficiency of weight was in each case observed. He regrets, however, that he “possessed no balance sufficiently accurate to determine exactly the deficiency of weight from the light liberated in different combustive processes.”

“From these experiments, it appears that in the chemical process of the formation of many oxyds and acids, light is liberated, the phosoxygen and combustible base consumed, and a new body formed.... Since light is liberated in these processes, it is evident that it must be liberated either from the phosoxygen or from the combustible body.... If the light liberated in combustion be supposed (according to Macquer’s and Hutton’s theories) to arise from the combustible body, then phosoxygen must be considered as a simple substance; and it follows on this supposition, that whenever phosoxygen combines with combustible bodies, either directly or by attraction from any of its combinations, light must be liberated, which is not the case, as carbon, iron and many other substances, may be oxydated by the decomposition of water without the liberation of light.”

Davy is here on the horns of a dilemma, but he ignores the difficulty, and, with characteristic “flexibility of adaptation,” proceeds to offer synthetical proofs “that the presence of light is absolutely essential to the production of phosoxygen.” The character of the “proofs” is sufficiently indicated by the following extracts:—

“When pure oxyd of lead is heated as much as possible, included from light, it remains unaltered; but when exposed to the light of a burning-glass, or even of a candle, phosoxygen is generated and the metal revivified.”

“Oxygenated muriatic acid [chlorine] is a compound of muriatic acid, oxygen and light, as will be hereafter proved. The combined light is not sufficient to attract the oxygen from the base [muriatic acid] to form phosoxygen; but its attraction for oxygen renders the [oxygenated muriatic] acid decomposable. If this acid be heated in a close vessel and light excluded no phosoxygen is formed; but if it be exposed to the solar light, phosoxygen is formed; the acid loses its oxygen and light and becomes muriatic acid.”

“A plant of Arenaria Tenuifolia planted in a pot filled with very dry earth, was inserted in carbonic acid, under mercury. The apparatus was exposed to the solar light, for four days successively, in the month of July. By this time the mercury had ascended considerably. The gas in the vessel was now measured. There was a deficiency of one-sixth of the whole quantity. After the carbonic acid was taken up by potash, the remaining quantity, equal to one-seventh of the whole, was phosoxygen almost pure. From this experiment, it is evident that carbonic acid is decomposed by two attractions; that of the vegetable for carbon and of light for oxygen: the carbon combines with the plant, and the light and oxygen combined are liberated in the form of phosoxygen.”

The accounts which Davy gives of his experiments, as well as of the phenomena which he professes to have observed, may awaken an uneasy doubt as to his absolute integrity; for, it is hardly necessary to point out, he could not possibly have obtained the results which he describes. The presence or absence of light in no wise affects the decomposition by heat of minium; chlorine, as he himself subsequently established, contains no oxygen; and a plant is incapable of decomposing pure undiluted carbonic acid, even in the brightest sunshine. But the work of a youth of nineteen, imaginative, sanguine, and impetuous, with no training as an experimentalist, and with only a limited access to scientific memoirs, cannot be judged by too severe a canon. The faculty of self-deception, even in the largest and most receptive minds, often in those of matured power and ripened experience, is boundless. Davy himself affords an exemplification of the truth of his own words, written years afterwards: “The human mind is always governed not by what it knows, but by what it believes; not by what it is capable of attaining, but by what it desires.”

It is not necessary to show how the presumptuous youth drove his hobby with all the reckless daring of a Phæton. Phlogiston and oxygen had in turn been the central conceptions of theories of chemistry; phosoxygen was to supplant them. It was to explain everything—the blue colour of the sky, the electric fluid, the Aurora Borealis, the phenomena of fiery meteors, the green of the leaf, the red of the rose, and the sable hue of the Ethiopian; perception, thought, and happiness; and why women are fairer than men. But Jupiter, in the shape of a Reviewer, soon hurled the adventurous boy from the giddy heights to which he had soared. The “West Country Collection” received scant sympathy from the critics, and the phosoxygen theory was either mercilessly ridiculed, or treated with contempt.

There is no doubt that Davy keenly felt the position in which he now stood. His pride was humbled, and the humiliation was as gall and wormwood. The vision of fame which his ardour had conjured up on the top of the Bristol coach—was it all a baseless fabric, and its train of honours and emoluments an insubstantial pageant? All he could plead was that his critics had not understood that these experiments were made when he had studied chemistry only four months, when he had never seen a single experiment executed, and when all his information was derived from Nicholson’s “Chemistry” and Lavoisier’s “Elements.” But his good sense quickly came to his rescue. After the first feelings of anger and mortification had passed, he recognised the justice of his punishment, much as he might resent the mode in which it was inflicted. How keen was the smart will appear from the following reflection, written in the August of the year in which the essays were published:—

“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 them; but one good experiment is of more value than the ingenuity of a brain like Newton’s.”

About the same time he wrote:—

“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.”

In the October of the same year he wrote:—

“Convinced as I am that chemical science is in its infancy, that an infinite variety of new facts must be accumulated before our powers of reasoning will be sufficiently extensive, I renounce my own particular theory as being a complete arrangement of facts: it appears to me now only as the most probable arrangement.”

By the end of the year the repentance was complete, and recantation followed. In a letter which appeared in Nicholson’s Journal in February, 1800, he corrects some of the errors into which he had fallen, and says, “I beg to be considered as a sceptic with regard to my own particular theory of the combinations of light, and theories of light in general.” To the end of his days Davy never forgot the lesson which his earliest effort had taught him; and there is no question that the memory of it acted as a salutary check on the exuberance of his fancy and the flight of his imagination. The wound to his self-love was, however, never wholly healed. Nothing annoyed him more than any reference to Beddoes’s book, and he declared to Dr. Hope that he would joyfully relinquish any little glory or reputation he might have acquired by his later researches were it possible to withdraw his share in that work and to remove the impression he feared it was likely to produce.

And yet, in spite of the unqualified censure with which they were received, and of the severe condemnation of them by their own author, we are disposed to agree with Dr. Davy that posterity will not suffer these essays to be wholly blotted out from the records of science. That the experimental part was for the most part radically bad, that the generalisation was hasty and presumptuous, and the reasoning imperfect, cannot be gainsaid. But, withal, the essays display some of Davy’s best and happiest characteristics. There is dignity of treatment and a sense of the nobility of the theme on which he is engaged; the literary quality is admirable; there is clearness of perception and perspicuity of statement; the facts as he knew them—or as he thought he knew them—are marshalled with ingenuity and with a logical precision worthy of his model and teacher Lavoisier; his style is sonorous and copious, even to redundancy—some of the periods indeed glow with all the fervour and richness of his Royal Institution lectures. However wild and visionary his speculations may seem, minds like those of Coleridge and Southey were not insensible to the intrinsic beauty of some of his ideas. His theory of respiration might not be true, but it had at least the merit of poetic charm in its consequence that the power and perspicacity of a thinker had some relation to the amount of light secreted by his brain. Even good old Dr. Priestley, whose Pegasus could never be stirred beyond the gentlest of ambles, tells us in the Appendix to his “Doctrine of Phlogiston Established” that Mr. H. Davy’s essays had impressed him with a high opinion of the philosophical acumen of their author. “His ideas were to me new and very striking; but,” he adds, with a caution that was not habitual, “they are of too great consequence to be decided upon hastily.”

Among the letters entrusted to me is one from Priestley, which must have been particularly gratifying to the young man. It is as follows:—

“Northumberland, Oct. 31, 1801.

“Sir,—I have read with admiration your excellent publications, and have received much instruction from them. It gives me peculiar satisfaction that, as I am far advanced in life, and cannot expect to do much more, I shall leave so able a fellow-labourer of my own country in the great fields of experimental philosophy. As old an experimenter as I am, I was near forty before I made any experiments on the subject of Air, and then without, in a manner, any previous knowledge of chemistry. This I picked up as I could, and as I found occasion for it, from books. I was also without apparatus, and laboured under many other disadvantages. But my unexpected success induced the friends of science to assist me, and then I wanted for nothing. I rejoice that you are so young a man; and perceiving the ardour with which you begin your career, I have no doubt of your success.

“My son, for whom you express a friendship, and which he warmly returns, encourages me to think that it may not be disagreeable to you to give me information occasionally of what is passing in the philosophical world, now that I am at so great a distance from it, and interested, as you may suppose, in what passes in it. Indeed, I shall take it as a great favour. But you must not expect anything in return. I am here perfectly insulated, and this country furnishes but few fellow-labourers, and these are so scattered, that we can have but little communication with each other, and they are equally in want of information with myself. Unfortunately, too, correspondence with England is very slow and uncertain, and with France we have not as yet any intercourse at all, tho we hope to have it soon....

“I thank you for the favourable mention you so frequently make of my experiments, and have only to remark that in Mr. Nicholson’s Journal you say that the conducting power of charcoal was first observed by those who made experiments on the pile of Volta; whereas it was one of the earliest that I made, and gave an account of in my History of Electricity, and in the Philosophical Transactions. And in your treatise on the Nitrous Oxide p. 55 you say, and justly, that I concluded this air to be lighter than that of the atmosphere. This, however, was an error in the printing that I cannot account for. It should have been alkaline air, as you will see the experiment necessarily requires.

“With the greatest esteem, I am Sir, yours sincerely

“J. Priestley.”

In Davy’s next contribution, “On the Silex composing the Epidermis, or External Bark, and contained in other parts of certain Vegetables,” published in Nicholson’s Journal in the early part of 1800, we find the evidence of a chastened and contrite spirit. The theme is humble enough, and the language as sober and sedate as that of Mr. Cavendish. The chance observation of a child that two bonnet-canes rubbed together in the dark produced a luminous appearance, led him to investigate the cause, which he found to reside in the crystallised silica present in the epidermis. Reeds and grasses, and the straw of cereals, were also found to be rich in silica, from which he concludes that “the flint entering into the composition of these hollow vegetables may be considered as analogous to the bones of animals; it gives to them stability and form, and by being situated in the epidermis more effectively preserves their vessels from external injury.” It is doubtful, however, whether the rigidity of the stems of cereals is wholly due to the silica they contain.

From a letter to Mr. Davies Gilbert, dated April 10th, 1799, we learn that he had now begun to investigate the effects of gases in respiration. In the early part of the year he had removed to a house in Dowry Square, Clifton, where he had fitted up a laboratory. After thanking his friend for his critical remarks on his recently published essays, he says:

“Your excellent and truly philosophic observations will induce me to pay greater attention to all my positions.... I made a discovery yesterday which proves how necessary it is to repeat experiments. The gaseous oxide of azote is perfectly respirable when pure. It is never deleterious but when it contains nitrous gas. I have found a mode of obtaining it pure, and I breathed to-day, in the presence of Dr. Beddoes and some others, sixteen quarts of it for near seven minutes. It appears to support life longer than even oxygen gas, and absolutely intoxicated me. Pure oxygen gas produced no alteration in my pulse, nor any other material effect; whereas this gas raised my pulse upwards of twenty strokes, made me dance about the laboratory as a madman, and has kept my spirits in a glow ever since. Is not this a proof of the truth of my theory of respiration? for this gas contains more light in proportion to its oxygen than any other, and I hope will prove a most valuable medicine.

“We have upwards of eighty out-patients in the Pneumatic Institution, and are going on wonderfully well.”

This observation of the respirability of nitrous oxide, and of the effects of its inhalation, was quickly confirmed. Southey, Coleridge, Tobin (the dramatist), Joseph Priestley, the son of the chemist, the two Wedgwoods, and a dozen other people of lesser note were induced to breathe the gas and to record their sensations. The discovery was soon noised abroad; Dr. Beddoes dispatched a short note to Nicholson’s Journal, and the fame of the Pneumatic Institution went up by leaps and bounds.

Maria Edgeworth, who was at the time on a visit to her sister, thus writes:—

“A young man, a Mr. Davy, at Dr. Beddoes’, who has applied himself much to chemistry, has made some discoveries of importance, and enthusiastically expects wonders will be performed by the use of certain gases, which inebriate in the most delightful manner, having the oblivious effects of Lethe, and at the same time giving the rapturous sensations of the Nectar of the Gods! Pleasure even to madness is the consequence of this draught. But faith, great faith, is I believe necessary to produce any effect upon the drinkers, and I have seen some of the adventurous philosophers who sought in vain for satisfaction in the bag of Gaseous Oxyd, and found nothing but a sick stomach and a giddy head.”

Laughing-gas, indeed threatened to become, like Priestley’s dephlogisticated air, “a fashionable article in luxury.” Monsieur Fiévée, in his “Lettres sur l’Angleterre, 1802,” names it in the catalogue of follies to which the English were addicted, and says the practice of breathing it amounted to a national vice!

Davy had no sooner discovered that the gas might be respired, than he proceeded to attack the whole subject of the chemistry of the oxides of nitrogen, and of nitrous oxide in particular, and after ten months of incessant labour he put together the results of his observations in an octavo volume, entitled, “Researches, Chemical and Philosophical, chiefly concerning Nitrous Oxide, or Dephlogisticated Nitrous Air, and its Respiration. By Humphry Davy, Superintendent of the Medical Institution.” The book appeared in the summer of 1800, and immediately re-established its author’s character as an experimentalist. Thomson, in his “History of Chemistry,” says of it: “This work gave him at once a high reputation as a chemist, and was really a wonderful performance, when the circumstances under which it was produced are taken into consideration.” In spite, however, of the eulogies with which it was welcomed, its sale was never very extensive, and a second edition was not required. In fact, the work as a whole was hardly calculated to attract the general public, whose only concern with laughing-gas was in its powers as an exhilarant. Indeed, this aspect of the question is not wholly lost on Davy himself, who is careful to point out that “if the pleasurable effects or medical properties of the nitrous oxide should ever make it an article of general request, it may be procured with much less time, labour, and expense than most of the luxuries, or even necessaries, of life”; and in a footnote he adds. “A pound of nitrate of ammonia costs 5s. 10d. (its present price is 9d.!). This pound, properly decomposed, produces rather more than 34 moderate doses of the air, so that the expense of a dose is about 2d. What fluid stimulus can be procured at so cheap a rate?”

To the chemical student the book had, and still has, many features of interest. It contains a number of important facts, based on original and fairly accurate observation. In the arrangement of these facts “I have been guided as much as possible,” says their author, “by obvious and simple analogies only. Hence, I have seldom entered into theoretical discussions, particularly concerning light, heat, and other agents, which are known only by isolated effects. Early experience has taught me the folly of hasty generalisation.” The work is divided into four main sections. The first chiefly relates to the production of nitrous oxide, and the analysis of nitrous gas and nitrous acid. He minutely studies the mode of decomposition of ammonium nitrate (first observed by Berthollet), and shows that it is an endothermic phenomenon, varying in character with the temperature and manner of heating. He is thus led to offer the following Speculations on the Decompositions of Nitrate of Ammonia:—

“All the phenomena of chemistry concur in proving that the affinity of one body, A, for another, B, is not destroyed by its combination with a third, C, but only modified; either by condensation or expansion, or by the attraction of C for B. On this principle the attraction of compound bodies for each other must be resolved into the reciprocal attractions of their constituents, and consequently the changes produced in them by variations of temperature explained from the alterations produced in the attractions of those constituents.”

The singular property possessed by ammonium nitrate of decomposing in several distinct modes according to the rapidity of heating and the temperature to which the substance is raised, first indicated by Davy, has been minutely studied by M. Berthelot, who has shown that this comparatively simple salt may be decomposed in as many as six different ways. It may be (1) dissociated into gaseous nitric acid and ammonia; (2) decomposed into nitrous oxide and water; (3) resolved into nitrogen, oxygen, and water, (4) or into nitric oxide, nitrogen, and water, (5) or into nitrogen, nitrogen peroxide, and water; or lastly (6), under the influence of spongy platinum, it may be resolved into gaseous nitric acid, nitrogen, and aqueous vapour. These different modes of decomposition may be distinct or simultaneous; or, more exactly, the predominance of any one of them depends on relative rapidity and on the temperature at which decomposition is produced. This temperature is not fixed, but is itself subordinate to the rapidity of heating (cf. Berthelot’s “Explosives and Their Power,” translated by Hake and Macnab). The assertion of De la Metherie, that the gas produced by the solution of platinum in nitromuriatic acid was identical with the dephlogisticated nitrous air of Priestley (nitrous oxide), led Davy to examine the gaseous products of this reaction more particularly. He had no difficulty in disproving the statement of the French chemist; but his observations, although accurate, led him to no definite conclusion. “It remains doubtful,” he says, “whether the gas consists simply of highly oxigenated muriatic acid and nitrogen, produced by the decomposition of nitric acid from the coalescing affinities of platina and muriatic acid for oxygen; or whether it is composed of a peculiar gas, analogous to oxigenated muriatic acid and nitrogen, generated from some unknown affinities.” The real nature of the gas, which has also been considered by Lavoisier as a particular species, not hitherto described, was first established by Gay Lussac, when Davy had himself proved that “oxigenated muriatic acid” was a simple substance.

In the second section the combinations and composition of nitrous oxide are investigated, and an account is given of its decomposition by combustible bodies, and a series of experiments are described which are now among the stock illustrations of the chemical lecture-room. As to its composition, he says, “taking the mean estimations from the most accurate experiments, we may conclude that 100 grains of the known ponderable matter of nitrous oxide consist of about 36·7 oxygen and 63·3 nitrogen”—no very great disparity from modern numbers, viz. 36·4 oxygen and 63·6 nitrogen. He concludes this section with a short review of the characteristic properties of the combinations of oxygen and nitrogen, among which he is led to class atmospheric air.

“That the oxygen and nitrogen of atmospheric air exist in chemical union, appears almost demonstrable from the following evidences.

“1^st. The equable diffusion of oxygen and nitrogen through every part of the atmosphere, which can hardly be supposed to depend on any other cause than an affinity between these principles.

“2^dly. The difference between the specific gravity of atmospheric air, and a mixture of 27 parts oxygen and 73 nitrogen, as found by calculation; a difference apparently owing to expansion in consequence of combination.”

These “evidences” had already been adduced by others, as stated by Davy; the first was subsequently disproved by Dalton, the second was based on inaccurate analyses of air.

To these Davy added two other “proofs” which originated with him:—

“3^dly. The conversion of nitrous oxide into nitrous acid, and a gas analogous to common air, by ignition.

“4^thly. The solubility of atmospheric air undecompounded.”

Of these it may be stated that the first is invalid, and the second not true. Nitrous oxide may, under certain circumstances, give rise to a mixture of oxygen and nitrogen, but not necessarily in the same proportion as in common air; and the air boiled out from water has not the same composition as atmospheric air.

Davy a few years afterwards obtained much clearer views as to the real nature of the atmosphere, and was, in fact, one of the earliest to recognise that it is merely a mixture of oxygen and nitrogen.

The third section consists of an account of observations on the action of nitrous oxide upon animals, and an investigation of the changes effected in it by respiration; whilst the fourth and last gives a history of the respirability and of the extraordinary effects of nitrous oxide, with details of experiments on its powers made by different individuals.

The last portion of the inquiry—in time of execution the first—is particularly interesting to the biographer of Davy, not only because the work in it was originated and carried out by him, but also from the light it incidentally throws on his character and genius:—

“A short time,” he says, “after I began the study of chemistry, in March 1798, my attention was directed to the dephlogisticated nitrous gas of Priestley, by Dr. Mitchell’s Theory of Contagion.” “Dr. Mitchell,” he tells us in a foot-note, “attempted to prove from some phenomenon connected with contagious diseases, that dephlogisticated nitrous gas which he called oxide of septon, was the principle of contagion, and capable of producing the most terrible effects when respired by animals in the minutest quantities, or even when applied to the skin or muscular fibre.” “The fallacy of this theory,” he continues, “was soon demonstrated by a few coarse experiments made on small quantities of the gas procured from zinc and diluted nitrous [nitric] acid. Wounds were exposed to its action, the bodies of animals were immersed in it without injury; and I breathed it mingled in small quantities with common air, without remarkable effects. An inability to procure it in sufficient quantities prevented me at this time from pursuing the experiments to any greater extent. I communicated an account of them to Dr. Beddoes.”

In the early part of April, 1799, he obtained nitrous oxide in a state of purity, and, as already stated, made the attempt to respire it.

“I was aware,” he says, “of the danger of this experiment. It certainly would never have been made if the hypothesis of Dr. Mitchell had in the least influenced my mind. I thought that the effects might be possibly depressing and painful, but there were many reasons which induced me to believe that a single inspiration of a gas apparently possessing no immediate action on the irritable fibre, could neither destroy nor immediately injure the powers of life.”

The experiment was made: the gas passed into the bronchia without stimulating the glottis, and produced no uneasy feeling in the lungs. There was a sense of fulness in the head accompanied with loss of distinct sensation and voluntary power—a feeling analogous to that produced in the first stage of intoxication, but unattended by pleasurable sensation. In company with Dr. Beddoes the experiment was repeated, with the following results:—

“Having previously closed my nostrils and exhausted my lungs, I breathed four quarts of nitrous oxide from and in to a silk bag. The first feelings were similar to those produced in the last experiment; but in less than half a minute, the respiration being continued, they diminished gradually, and were succeeded by a sensation analogous to gentle pressure on all the muscles attended by a highly pleasurable thrilling, particularly in the chest and the extremities. The objects around me became dazzling, and my hearing more acute. Towards the last inspirations, the thrilling increased, the sense of muscular power became greater, and at last an irresistible propensity to action was indulged in; I recollect but indistinctly what followed; I know that my motions were various and violent. These effects very soon ceased after respiration. In ten minutes I had recovered my natural state of mind. The thrilling in the extremities continued longer than the other sensations. This experiment was made in the morning; no langour or exhaustion was consequent, my feelings throughout the day were as usual, and I passed the night in undisturbed repose. The next morning the recollections of the effects of the gas were very indistinct, and had not remarks written immediately after the experiment recalled them to my mind I should have even doubted of their reality. I was willing indeed to attribute some of the strong emotion to the enthusiasm, which I supposed must have been necessarily connected with the perception of agreeable feelings, when I was prepared to experience painful sensations. Two experiments, however, made in the course of this day, with scepticism, convinced me that the effects were solely owing to the specific operation of the gas.”

Having thus ascertained the powers of the gas, he made many experiments to ascertain the length of time it might be breathed with safety, its action on the pulse, and its general effects on the health when often respired.

After a number of experiments made to determine its effect in allaying fatigue, in inducing sleep, or in alleviating the after-effects of vinous intoxication, he resolved

“to breathe the gas for such a time and in such quantities as to produce excitement equal in duration and superior in intensity to that occasioned by high intoxication from opium or alcohol.”

For this purpose he was enclosed in an air-tight or box-chamber, into which from time to time, by the help of Dr. Kinglake, successive quantities of twenty quarts of nitrous oxide were introduced. As he breathed the gas, he found that his temperature and pulse gradually increased. He experienced a generally diffused warmth without the slightest moisture of the skin, a sense of exhilaration similar to that produced by a small dose of wine, and disposition to muscular motion and to merriment. Luminous points seemed frequently to pass before his eyes, his hearing became more acute, and he felt a pleasant lightness and power of exertion in the muscles; and, on account of the great desire of action, rest was painful. After having been in the box for an hour and a quarter he began to respire twenty quarts of unmingled nitrous oxide. What followed is best described in his own words:—

“A thrilling, extending from the chest to the extremities, was almost immediately produced. I felt a sense of tangible extension highly pleasurable in every limb; my visible impressions were dazzling, and apparently magnified, I heard distinctly every sound in the room, and was perfectly aware of my situation. By degrees, as the pleasurable sensations increased, I lost all connection with external things; trains of vivid visible images rapidly passed through my mind, and were connected with words in such a manner, as to produce perceptions perfectly novel. I existed in a world of newly connected and newly modified ideas: I theorised, I imagined that I made discoveries. When I was awakened from this semi delirious trance by Dr. Kinglake, who took the bag from my mouth, indignation and pride were the first feelings produced by the sight of the persons about me. My emotions were enthusiastic and sublime, and for a minute I walked round the room perfectly regardless of what was said to me. As I recovered my former state of mind I felt an inclination to communicate the discoveries I had made during the experiment. I endeavoured to recall the ideas: they were feeble and indistinct; one collection of terms however presented itself; and with a most intense belief and prophetic manner, I exclaimed to Dr. Kinglake, ‘Nothing exists but thoughts! The universe is composed of impressions, ideas, pleasures and pains!’”

As might be anticipated, the friend of Coleridge and Southey, himself a youth of sensibility and poetic feeling, was curious to learn whether this wonderful gas would increase his stock of the divine afflatus. He walked amidst the scenery of the Avon, “rendered exquisitely beautiful by bright moonshine,” and, with a mind filled with pleasurable feelings, he breathed the gas, and we have as a consequence the following effusion:—