Shortly after Davy’s return to England his sympathy was enlisted in a cause which enabled him to display all the attributes of his genius, and to achieve a triumph which, while greatly enhancing his popular reputation, added no little to his scientific fame. To show him how he might be useful, was at all times a certain method of securing his interest; for, like Lavoisier, he was even more the friend of humanity than of science, and to make science serviceable to humanity was, he considered, the highest object of his calling.
During the early years of this century the country was repeatedly shocked by the occurrence of a succession of disastrous colliery explosions, especially in the north of England, attended by great destruction of life and property and widespread misery and destitution. The development of our iron-trade, the improvements in the steam-engine, and the more general application of machinery to industry had greatly stimulated the opening out of our coal-fields; and the working of coal was being extended with a rapidity that greatly aggravated the evils and dangers at all times inseparable from it. In the early days of coal-getting, when the pits were shallow and the workings comparatively near the shafts, fire-damp, although not unheard of, was little dreaded, and explosions were rare—so rare, indeed, that when they occurred they were thought worthy of mention in the Philosophical Transactions of the Royal Society. As the pits became deeper, and the ways more extended, explosions became more frequent, and at times it was impossible to work the coal, owing to the accumulation of fire-damp and its liability to “fire” at the candles of the miners. In 1732 attempts were first made to ventilate the pits by “fire-lamps” or furnaces, and by mechanical means, so as to sweep out the “sulphur” by means of fresh air. Carlisle Spedding, a little later, invented the steel mill—a contrivance by which a disc of steel was caused to revolve against a piece of flint, so as to throw off a shower of sparks sufficiently luminous to enable the miner to carry on his business.
In spite of the “spark-emitting wheel,” and of the systems of ventilation introduced by Ryan, James Spedding, John Buddle, and others, “the swart demon of the mine” grew more and more formidable, and demanded a greater number of victims every year. Mechanical science would appear to have spent itself, and the mining world was gradually coming to look upon fire-damp with the fatalism with which ignorant and superstitious people regard the plague. Some of the great coal owners—powerless to do more, but afraid of the rising tide of public opinion—used their influence with the newspapers to suppress all allusion to these calamities. But many persons, especially the physicians and clergymen in the mining districts, who were witnesses of the suffering and distress which the “firing” of a mine occasioned, kept public attention alive by means of pamphlets and letters and notices to such journals as would insert their communications. One colliery—the Brandling Main or Felling Colliery, near Gateshead-on-Tyne—acquired an unenviable notoriety from the frequency with which it fired. On May 25th, 1812, an explosion occurred which killed ninety-two men and boys. No calamity of such magnitude had ever happened before in a coal mine. Eighteen months afterwards a second explosion took place by which twenty-three lives were lost. In the following year explosions occurred at Percy Main, Hebburn, and Seafield. In June, 1815, Newbottle Colliery exploded with the loss of fifty-seven men and boys, and this was immediately followed by a similar disaster at Sheriff Hill. The Rev. Mr. Hodgson—the historian of Northumberland—in whose parish the Brandling Main was situated, published a particular account of the first Felling Colliery Explosion. This was widely circulated, and ultimately found its way into Thomson’s Annals of Philosophy, which continued to print accounts of similar accidents as they occurred. At length Mr. J.J. Wilkinson, a barrister resident in the Temple, suggested the formation of a society to investigate the whole subject and to seek for remedies. The Bishop of Durham and the Rev. Dr. Gray, afterwards Bishop of Bristol, but then Rector of Bishopwearmouth, led the way, and ultimately the society was instituted on October 1st, 1813, with Sir Ralph Millbanke, afterwards Sir Ralph Noel, as President. Its first report contains a letter from Mr. John Buddle, the great authority on the ventilation of coal mines, in which he expresses his conviction that mechanical agencies are practically powerless to prevent explosions in mines subjected to sudden bursts of fire-damp, and he concludes
“that the hopes of this society ever seeing its most desirable object accomplished must rest upon the event of some method being discovered of producing such a chemical change upon carburetted hydrogen gas as to render it innoxious as fast as it is discharged, or as it approaches the neighbourhood of lights. In this view of the subject, it is to scientific men only that we must look up for assistance in providing a cheap and effectual remedy.”
The society received a number of suggestions, for the most part wholly impracticable, and generally of the character of that of Dr. Trotter, who proposed to flood the mines with chlorine. A variety of air-tight or insulated lamps were suggested by Clanny, Brandling, Murray, and others, much on the same lines as that devised by Humboldt, but none of them appears to have been seriously tried.
Under these circumstances it was decided to ask for the co-operation of Davy, and with that object Mr. Wilkinson called upon him at the Royal Institution, in the autumn of 1813, but found he had left for Paris. A few months after his return the Rev. Dr. Gray wrote to him on the subject, and received the following letter in reply:—
“August 3, 1815.
“....
“It will give me great satisfaction if my chemical knowledge can be of any use in an enquiry so interesting to humanity, and I beg you will assure the committee of my readiness to co-operate with them in any experiments or investigations on the subject.
“If you think my visiting the mines can be of any use, I will cheerfully do so.
* * * * *
“I shall be here ten days longer, and on my return South, will visit any place you will be kind enough to point out to me, where I may be able to acquire information on the subject of coal gas.”
Dr. Gray, in reply, referred him to Mr. John Buddle, of the Wallsend Colliery.
On August 24th, 1815, Mr. Buddle wrote to Dr. Gray:—
“Permit me to offer my best acknowledgments for the opportunity which your attention to the cause of humanity has afforded me of being introduced to Sir Humphry Davy. “I was this morning favoured with a call from him, and he was accompanied by the Rev. Mr. Hodgson. He made particular enquiries into the nature of the danger arising from the discharge of the inflammable gas in our mines. I shall supply him with a quantity of the gas to analyze; and he has given me reason to expect that a substitute may be found for the steel mill, which will not fire the gas. He seems also to think it possible to generate a gas, at a moderate expense, which, by mixing with the atmospheric current, will so far neutralise the inflammable air, as to prevent it firing at the candles of the workmen.
“If he should be so fortunate as to succeed in either the one or the other of these points, he will render the most essential benefit to the mining interest of this country, and to the cause of humanity in particular.”
After spending a few days in the district with Mr. Hodgson and Dr. Gray, in the course of which he saw and experimented with Dr. Clanny’s lamp, he went on a round of visits in Durham and Yorkshire, and arrived in London at the end of September. Early in October a quantity of fire-damp was sent to him by Mr. Hodgson, the receipt of which he acknowledged on the 15th, saying:—
“My experiments are going on successfully and I hope in a few days to send you an account of them; I am going to be fortunate far beyond my expectations.”
Four days afterwards he again wrote to Mr. Hodgson stating that he had discovered
“that explosive mixtures of mine-damp will not pass through small apertures or tubes; and that if a lamp or lanthorn be made air-tight on the sides, and furnished with apertures to admit the air, it will not communicate flame to the outward atmosphere.”
On the 25th October he gave an account of his work to the Chemical Club. On October 30th he wrote to Dr. Gray and to Mr. Hodgson, giving a description of three forms of safe lamps. His letter to Dr. Gray was as follows:—
“As it was the consequence of your invitation that I endeavoured to investigate the nature of the fire-damp, I owe to you the first notice of the progress of my experiments.
“My results have been successful far beyond my expectations. I shall enclose a little sketch of my views on the subject; and I hope in a few days to be able to send a paper with the apparatus for the committee. I trust the safe lamp will answer all the objects of the collier.
“I consider this at present as a private communication. I wish you to examine the lamps I have had constructed, before you give any account of my labours to the committee.
“I have never received so much pleasure from the result of any of my chemical labours; for I trust the cause of humanity will gain something by it.”
Mr. Hodgson’s letter was shown to several persons, and appears to have been copied by some, on or about November 2nd, and an extract from it appeared in Dunn’s “View of the Coal Trade.”
On November 9th Davy read his first paper on the subject before the Royal Society; it was entitled “On the fire-damp of coal mines, and on the methods of lighting the mines so as to prevent its explosion.” After describing the manner in which his attention had been specially called to the subject, he states that he first made experiments with a variety of phosphori (Kunckel’s, Canton’s, and Baldwin’s), and also with the electrical light in close vessels, in the hope that they might be found to afford the requisite amount of illumination; but the results were not encouraging.
After an account of the chemical characters of the fire-damp sent to him by Mr. Hodgson, he describes the results of experiments on its combustibility and explosive nature, and on the degree of heat required to explode it when mixed with air. In respect of its combustibility fire-damp was found to differ most materially from the other common inflammable gases in that it required a far higher temperature to effect its inflammation or explosion. Moreover, it was found that the flame formed by the union of air and fire-damp would not pass through tubes of a certain minimum diameter;
“and in comparing 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.”
The observation that mixtures of air and coal-gas would not explode in very narrow tubes had been previously made, unknown to Davy, by Wollaston and Tennant. Davy likewise found that explosions would not pass through very fine wire sieves or wire gauze. He also noted that an admixture of carbonic acid and nitrogen, even in small proportions, with explosive mixtures of fire-damp greatly diminished the velocity of the inflammation.
“... It is evident then, that to prevent explosions in coal mines it is only necessary to use air-tight lanterns, supplied with air from tubes or canals of small diameter, or from apertures covered with wire-gauze placed below the flame, through which explosions cannot be communicated and having a chimney at the upper part, as a similar system for carrying off the foul air; and common lanterns may be easily adapted to the purpose by being made air-tight in the door and sides, by being furnished with the chimney and the system of safety apertures below and above. The principle being known, it is easy to adapt and multiply practical applications of it.”
DAVY’S EXPERIMENTAL SAFETY LAMPS.
He then devised a number of lamps on this principle, and subjected them to trial with explosive mixtures in various ways. The plate on page 199, copied from the original paper in the Philosophical Transactions, shows the successive forms through which the lamps passed.
On January 11th, 1816, he read a second paper to the Royal Society, entitled, “An account of an invention for giving light in explosive mixtures of fire-damp in coal mines by consuming the fire-damp,” in which he shows that the tubes or canals as well as the sides of the lanterns may be replaced by cages or cylinders of wire gauze. The inflammable mixture will readily pass through the meshes of the gauze and will burn within it, filling the cylinder with a bright flame, but no explosion will pass outwards, even although the wire becomes heated to redness.
A fortnight later he read a third paper to the Society, “On the Combustion of Explosive Mixtures confined by Wire Gauze, with some Observations on Flame,” in which he gives the results of further inquiries respecting the limits of the size of the apertures, and of the wire in the metallic gauze required to shield the flame of an oil-lamp, and describes a number of illustrations of the action of the gauze in lowering the temperature of the explosive mixture below the point of ignition. Some of these illustrations are now among the stock experiments of the lecture theatre. He offers some observations concerning the essential nature of flame, and concludes by informing the Society that his “cylinder lamps [i.e. lamps of which the flames are enclosed within a cylinder of gauze: see Fig. 11, p. 199] have been tried in two of the most dangerous mines near Newcastle with perfect success.”
The form which the lamp finally took in the hands of Mr. Newman, the instrument-maker, is seen on p. 200.
The trials above referred to were first made by Mr. Matthias Dunn and the indefatigable Mr. Hodgson in the Hebburn Colliery, and shortly afterwards by Mr. John Buddle in the Wall’s End Colliery. Mr. Buddle has placed on record his impressions of his first experience.
“I first tried it,” he says, “in an explosive mixture on the surface; and then took it into a mine; ... it is impossible for me to express my feelings at the time when I first suspended the lamp in the mine and saw it red hot.... I said to those around me ‘We have at last subdued this monster.’”
Some months afterwards Davy accompanied Mr. Buddle into the pit and saw his lamp in actual use.
“Sir Humphry was delighted,” says Mr. Buddle, “and I was overwhelmed with feelings of gratitude to that great genius which had produced it.”
Further testimony of Mr. Buddle’s appreciation of this memorable invention may be seen from the following extract from a letter by him to Davy. It is not only interesting in view of Davy’s remark that “the evidence of the use of a practical discovery is of most value when furnished by practical men,” but also as showing the rapidity with which the discovery was taken advantage of:—
“Walls End Colliery, Newcastle, June 1st, 1816.
“After having introduced your safety lamp into general use in all the collieries under my direction, where inflammable air prevails, and after using them daily in every variety of explosive mixture, for upwards of three months, I feel the highest possible gratification in stating to you that they have answered to my entire satisfaction.
“The safety of the lamps is so easily proved by taking them into any part of a mine charged with fire-damp, and all the explosive gradations of that dangerous element are so easily and satisfactorily ascertained by their application, as to strike the minds of the most prejudiced with the strongest conviction of their high utility; and our colliers have adopted them with the greatest eagerness.
“Besides the facilities afforded by this invention to the working of coal mines abounding in fire-damp, it has enabled the directors and superintendents to ascertain, with the utmost precision and expedition, both the presence, the quantity, and the correct situation of the gas. Instead of creeping inch by inch with a candle, as is usual, along the galleries of a mine suspected to contain fire-damp, in order to ascertain its presence, we walk firmly in with the safe lamps, and with the utmost confidence prove the actual state of the mine. By observing attentively the several appearances upon the flame of the lamp, in an examination of this kind, the cause of accidents which have happened to the most experienced and cautious miners is completely developed; and this has been, in a great measure, matter of mere conjecture.
“I feel peculiar satisfaction in dwelling upon a subject which is of the utmost importance, not only to the great cause of humanity, and to the mining interest of the country, but also to the commercial and manufacturing interests of the United Kingdom; for I am convinced that by the happy invention of the safe lamp large proportions of the coal mines of the empire will be rendered available, which otherwise might have remained inaccessible, at least without an invention of similar utility, which could not have been wrought without much loss of the mineral, and risk of life and capital.
“It is not necessary that I should enlarge upon the national advantages which must necessarily result from an invention calculated to prolong our supply of mineral coal, because I think them obvious to every reflecting mind; but I cannot conclude, without expressing my highest sentiments of admiration for those talents which have developed the properties, and controlled the power, of one of the most dangerous elements which human enterprise has hitherto had to encounter.”
This letter is only one of many received by Davy from practical men, all telling the same story of wonder and astonishment “that so simple a looking instrument should defy an enemy heretofore unconquerable”; and all expressing the deepest gratitude to him as its inventor, often in language which gains in force, and even in eloquence, from its very homeliness and simple pathos.
The following address from the Whitehaven colliers was among the papers lent to me by Dr. Rolleston:—
“September 18, 1816.
“We, the undersigned, miners at the Whitehaven Collieries, belonging to the Earl of Lonsdale, return our sincere thanks to Sir Humphry Davy, for his invaluable discovery of the safe lamps, which are to us life preservers; and being the only return in our power to make, we most humbly offer this, our tribute of gratitude.”
The names of eighty-two miners are appended—the majority of them—viz. forty-seven—with their mark (+) affixed.
What the learned world thought may be judged from the following extracts from an article in the Edinburgh Review—a periodical not always characterised by a just appreciation of the work of the Royal Institution professors, for the literature of science contains few things more disingenuous or more spiteful than the attack of “the young gentleman from Edinburgh”—afterwards known as Lord Brougham—on Thomas Young when he first made known the undulatory theory of light. In the Review for February, 1816, Mr. Playfair begins his article on Davy’s discovery by pointing out that—
“The safe lamp is a present from philosophy to the arts, and to the class of men furthest removed from the influence of science. The discovery is in no degree the effect of accident; and chance, which comes in for so large a share in the credit of human inventions, has no claims on one which is altogether the result of patient and enlightened research....
“This is exactly such a case as we should choose to place before Bacon, were he to revisit the earth, in order to give him, in a small compass, an idea of the advancement which philosophy has made, since the time when he had pointed out to her the route which she ought to pursue. The great use of an immediate and constant appeal to experiment cannot be better evinced than in this example. The result is as wonderful as it is important. An invisible and impalpable barrier made effectual against a force the most violent and irresistible in its operations; and a power, that in its tremendous effects seemed to emulate the lightning and the earthquake, confined within a narrow space, and shut up in a net of the most slender texture,—are facts which must excite a degree of wonder and astonishment from which neither ignorance nor wisdom can defend the beholder. When to this we add the beneficial consequences and the saving of the lives of men and consider that the effects are to remain as long as coal continues to be dug from the bowels of the earth, it may fairly be said that there is hardly in the whole compass of art or science a single invention of which one would rather wish to be the author.”
Davy was urged by several of his friends to protect his invention by a patent. Among them was Mr. Buddle, who pointed out to him that he might have received his five or ten thousand a year from it.
“My good friend,” was his answer, “I never thought of such a thing: 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.... More wealth could not increase either my fame or my happiness. It might undoubtedly enable me to put four horses to my carriage; but what would it avail me to have it said that Sir Humphry drives his carriage and four?”
The gratitude of some of the leading colliery proprietors for an invention so unselfishly placed at their disposal found expression in a letter from the chairman of a general meeting of the coal-owners held at Newcastle on March 18th, 1816, conveying the terms of a vote of thanks. A few months afterwards it was determined that their appreciation should take a more substantial form, and a general meeting of the coal-owners was held at Wallsend Colliery on August 31st, 1816, at which it was resolved to make Davy a present of plate.
A note of opposition was at once sounded, and it came from one of the proprietors of the Felling Colliery. Mr. W. Brandling urged that it was not proved that Sir Humphry Davy was the first and true inventor of the safety lamp, or even the discoverer of the principle on which it was based.
“The conviction,” he said, “upon my mind is, that Mr. George Stephenson, of Killingworth Colliery, is the person who first discovered and applied the principle upon which safe lamps may be constructed; for whether the hydrogen gas is admitted through capillary tubes, or through the apertures of wire-gauze, which may be considered as merely the orifices of capillary tubes, does not, as I conceive, in the least affect the principle.”
The opposition thus started very quickly gathered strength, and by appeals to local prejudice and to ignorance a degree of heat and even animosity was imported into the question, which served no other purpose than to confuse the true issue. At an adjourned meeting of the coal-owners held on October 11th, 1816, Mr. William Brandling moved—
“That the meeting do adjourn, until by a comparison of dates it shall be ascertained whether the merit of the safety lamp belongs to Sir Humphry Davy, or to Mr. George Stephenson.”
Although Mr. Brandling failed to convince the meeting, it becomes necessary in the interests of truth and justice to examine the grounds upon which George Stephenson—a man of undoubted genius, and of an integrity as blameless as that of Davy, and who, as the pioneer of railway enterprise, subsequently acquired a fame as high and as deserved as that of the great chemist—has claims to be regarded as an inventor of the safety lamp. In equity, it must be admitted that the question is not merely a question of dates, for in assigning merit in a matter of this kind the calmer judgment of posterity is not wholly swayed by priority of date; it looks to circumstances, conditions, motives, and it apportions its meed of approbation accordingly. The glory of Priestley as an independent discoverer of oxygen is in nowise dimmed by the circumstance that Scheele is now known to have discovered it before him. It cannot be truthfully asserted that Davy was not an independent inventor of the safety lamp. What has to be determined is, has George Stephenson any such claim?
Stephenson’s claim has been ably and temperately stated by Dr. Smiles in his biography of George Stephenson, in “The Lives of the Engineers,” but an unbiassed review of the evidence will convince most people that, however certain it may be that the Killingworth engine-tenter was an independent searcher after a method of protecting a flame, it is equally certain that he was not the discoverer of the true principle on which the safety lamp is constructed, and that the lamp associated with his name, although it bears the impress of the crude ideas with which he started, owes its real merit to the discoveries of Davy. This controversy and the feeling it gave rise to greatly exasperated Davy, and his anger is manifested in his letters at the time. The action of the Brandlings he seemed to think was inspired by the most unworthy motives. As to his rival, he says:—
“I never heard a word of George Stephenson and his lamps till six weeks after my principle of security had been published; and the general impression of the scientific men in London, which is confirmed by what I heard at Newcastle, is, that Stephenson had some loose idea floating in his mind, which he had unsuccessfully attempted to put in practice till after my labours were made known;—then, he made something like a safe lamp, except that it is not safe, for the apertures below are four times, and those above twenty times too large; but, even if Stephenson’s plans had not been posterior to my principles, still there is no analogy between his glass exploding machine, and my metallic tissue permeable to light and air, and impermeable to flame.”
On the 25th of September, 1817, as Davy passed through Newcastle on his return from Scotland, the coal-owners who had subscribed to his testimonial invited him to a banquet and presented him with the plate, which, in accordance with his wishes, took the form of a dinner-service. “I wish,” he had said, “that even the plate from which I eat should awaken my remembrance of their liberality, and put me in mind of an event which marks one of the happiest periods of my life.” The chairman—his friend Mr. Lambton, afterwards the Earl of Durham, and who was with him under the care of Dr. Beddoes at Bristol—made the presentation in an impressive and felicitous speech, and Davy acknowledged it in terms worthy of himself and of the occasion. In a subsequent speech, in response to the toast of his health, he dilated upon the theme always uppermost in his mind, and to which he never neglected the opportunity to give utterance, namely, the benefit of abstract science to mankind. He had an admirable moral to which to point, and it was driven home with all his wonted skill and power.
In what manner this plate, which was valued at about £2,500, was subsequently made subservient to the interests of science will be seen hereafter.
The friends of Stephenson were not wanting in the courage of their convictions or in determination to give substantial proof of it. In the following November they met and resolved that as in their opinion Mr. G. Stephenson had been the first to discover the principle of safety and to apply it, he was entitled to some reward. Whereupon Davy’s friends again assembled in public meeting on November 26th, 1817, and passed resolutions to the effect that in their opinion the merit belonged to Sir Humphry Davy alone, and that Stephenson’s latest lamps were evident imitations of those of Sir Humphry Davy; and they further ordered that copies of their resolutions should appear in a number of local, London, and Edinburgh papers, and be sent to the principal owners and lessors of collieries upon the Tyne and Wear. Davy’s friends in London also exerted themselves in his behalf, and a copy of resolutions similar in purport to those passed in Newcastle, signed by Sir Joseph Banks, P.R.S., Brande, Hatchett, and Wollaston, was sent to the newspapers.
Mr. Brandling and his friends eventually collected about £800 (including 100 guineas which the meeting of October 11th had awarded Stephenson as an acknowledgment of his efforts to construct a safe lamp), and gave it, together with a silver tankard, to Mr. Stephenson at a public dinner in January, 1818.
This is not the place to follow the subsequent history of the Davy lamp, or to describe the various modifications which have grown out of it, or even to show the dangers which a larger experience reveals as latent in its original form. These dangers have in great measure arisen from the development of the very system of ventilation which Buddle himself instituted; and he who in his joy exultingly exclaimed, “At last, we have subdued this monster!” has unwittingly contributed to the maleficent activity of the monster in coping with the lamp as Buddle knew it.
In the course of his numerous trials made to elucidate the principle of the safety lamp, Davy observed certain peculiarities connected with flame which led him to take up the general question. Hence arose a series of investigations, which have contributed in no small degree to our knowledge of a particularly difficult and intricate subject.
He proved, in the first place, that flame must be considered as an explosive mixture of inflammable gas or vapour and air, and that the heat communicated by it must depend upon its mass. The different appearance of a flame of coal gas burning in a jet in the open air, and in his safety lamp mixed with common air, led him to investigate the cause of luminosity in flame. He says:—
“In reflecting on the circumstances of the two species of combustion I was led to imagine that the cause of the superiority of the light of the stream of coal gas might be owing to the decomposition of a part of the gas towards the interior of the flame, where the air was in smallest quantity, and the deposition of solid charcoal, which, first by its ignition, and afterwards by its combustion, increased in a high degree the intensity of the light.”
The principle of the increase of the brilliancy and density of flame by the production and ignition of solid matter explains the appearance of the different parts of the flames of burning bodies, and of the blow-pipe flame; it also explains the intensity of the light of those flames in which fixed solid matter is produced in combustion, e.g. phosphorus and zinc in oxygen, potassium in chlorine; and, on the other hand, the feebleness of the light of flames in which gaseous and volatile matter is alone produced, e.g. hydrogen in oxygen, phosphorus in chlorine. Davy’s theory has not been unchallenged, but all subsequent research, when pushed sufficiently far, has shown that, as regards all ordinary illuminating flames, i.e. carbonaceous flames—e.g. coal-gas, oil, paraffin, candle—the presence of solid incandescent carbon is a prime cause of their luminosity. It had been observed that the rarefaction of a mixture of inflammable gases diminishes its combustibility: Davy proved that this diminution was not the result of the removal of pressure per se, but of the cooling effect thus indirectly produced. Hence, the lower the temperature of ignition of a gaseous mixture the more it may be rarefied without becoming uninflammable. In like manner he shows that by heating the gaseous mixture it may be caused to explode at a lower temperature, and that when gases combine by sudden compression, the combination is caused by the heat evolved. Also that the power of an indifferent gas to prevent the explosion of a gaseous mixture depends upon its power of abstracting heat, and that the higher the temperature of ignition of the explosive mixture the less is the amount of indifferent gas required to stop the explosion. He proved that it was quite possible to effect the gradual combination of gases without flame—that is, without the production of heat sufficient to raise the products to incandescence; and he discovered the singular fact that platinum would induce the combination of many inflammable gases and vapours, and on this circumstance based the construction of his flameless lamp.
* * * * *
In the early summer of 1818, he thus wrote to his mother:—
“My dear Mother,—We are just going on a very interesting journey. I am first to visit the coal miners of Flanders, who have sent me a very kind letter of invitation and of thanks for saving their lives. We are then going to Austria, where I shall show Vienna to Lady Davy, and then visit the mines; and lastly, before I return, we are going to visit Naples.
“I have the commands of his Royal Highness the Prince Regent to make experiments upon some very interesting ancient manuscripts, which I hope to unfold. I had yesterday the honour of an audience from his Royal Highness, and he commissioned me to pursue this object in the most gracious and kind manner....
“We shall be absent some months. With kindest love to my sisters and my aunts,
“I am, my dear mother,
“Your most affectionate son,
“H. Davy.”
A few months after this visit to the Prince Regent he received the intimation that he had been created a baronet.
He arrived at Naples in the autumn, and began his researches on the Herculaneum manuscripts referred to in his letter. His first results were sufficiently encouraging to induce him to make some prolonged experiments with a view of discovering a method of unfolding them. He found that the papyri had suffered not so much from fire, as was believed, as from a gradual change in vegetable structure, similar to that which accompanies the transformation of vegetable matter into lignite. He managed to unroll a number, and an account of his results was communicated to the Royal Society in 1821. But from the fragmentary character of the papyri these were found to be of little value to literature. Subsequently difficulties were put in his way by the curators of the museum, and ultimately his investigations were abandoned, not without some little exhibition of temper and resentment on his part.
During his stay at Naples he again interested himself in the volcanic phenomena of Vesuvius, and his observations constitute the material of a paper which was published in the Philosophical Transactions in 1827, and many of his personal experiences in connection with the subject are referred to in his last work, “Consolations in Travel.”
He left Naples in the spring of 1819, and after a short stay at the baths of Lucca he went for the summer and early autumn into the Tyrol, whence he again proceeded to Lucca, and on the approach of winter returned to Naples, where he arrived on December 1st. He quitted it in the spring of 1820, and travelled slowly home by the south of France and Bordeaux, arriving in England about the middle of June. On the 19th of that month Sir Joseph Banks died, and so terminated his forty-two years’ presidency of the Royal Society, to which position he was elected before Davy was even born. Davy immediately announced his intention of becoming a candidate for the vacant chair, and was elected at the following anniversary meeting on November 30th.
