Chapter VIII

MARRIAGE--KNIGHTHOOD--ELEMENTS OF CHEMICAL PHILOSOPHY--NITROGEN TRICHLORIDE--FLUORINE.

Davy was now (1810) thirty-two years of age, and near the summit of his scientific fame, and perhaps also, says his brother John, who was then in daily association with him, at the height of his happiness.

“He had earned an unsullied and noble reputation; he was loved
and admired by friends, who had cheered him on in his career;
he had hardly passed the prime of manhood; he was in possession
of excellent health; he had open to him almost every source of
ordinary recreation and enjoyment; and he had, besides, the
unfailing pleasures derived from the active and successful
pursuit of science. His letters written at this time, [to his
mother and sisters] strongly mark a happy contentment, as well as
a very amiable and affectionate state of mind.”

His popularity at the Royal Institution was unbounded; indeed, he was the very prop of its existence, and was so recognised. But honourable as his position was, it brought him little more than a competency; and however generously disposed the Managers might have felt towards him, the financial circumstances of the Institution afforded no certainty of a future independence. The Bishop of Durham and Sir Thomas Bernard sought to induce him to enter the Church, in the hope that his talents and eloquence would minister no less to the cause of religion than to his own prospects of preferment. At this period he had serious thoughts of again applying himself to the study of medicine, with a view of practising as a physician, and he actually entered his name at Cambridge and kept some terms there. But whether the unfortunate experience of his colleagues Wollaston and Young deterred him, or whether, as is more probable, Science had too strong a hold upon his affections, it is certain he made no resolute attempt to abandon her.

Money was never an object with Davy, except as the means of procuring him the advantages which the moneyed classes can command; had he cared for it, his talents were a marketable commodity, and would have brought him riches in many ways. The smiling goddess now showed him one way as honourable as it was lucrative and pleasurable. The Dublin Society invited him to lecture to them on the discoveries which had made him famous, with the promise of a more substantial token of their appreciation than the sound of their applause.

The following minutes from the Proceedings of the Society serve to explain this:--

“May 3, 1810. _Resolved_--That it is the wish of the Society
to communicate to the Irish public in the most extended manner
(consistent with the engagements of the Society), the knowledge
of a science so intimately connected with the improvement of
agriculture and the arts, which is their great object to promote;
and that, with this view, it appears to them extremely desirable
to obtain the fullest communication of the recent discoveries in
electro-chemical science which have been made by Mr. Davy.

“_Resolved_--That application be made to the Royal Society
requesting that they be pleased to dispense with the engagements
of Mr. Davy [as Secretary], so far as to allow the Dublin
Society to solicit the favour of his delivering a course of
electro-chemical lectures in their new laboratory, as soon as may
be convenient after the present course of chemical lectures shall
have been completed by their professor, Mr. Higgins.

“_Resolved_--That the sum of 400 guineas be appropriated out
of the funds of the Society, to be presented to Mr. Davy, as a
remuneration, which they propose him to accept, and as a mark of
the importance they attach to the communication they solicit.”

We further read: “Mr. Davy arrived in Dublin and delivered his course of lectures to a crowded auditory.” At the close of his lectures the following resolution was passed:--

“November 29th, 1810. _Resolved_--That the thanks of the Society
be communicated to Mr. Professor Davy, for the excellent course
of lectures which, at their request, he has delivered in their
new laboratory; and to assure him, that the views which led the
Society to seek for these communications have been answered even
beyond their hopes; that the manner in which he has unfolded his
discoveries has not only imparted new and valuable information,
but, further, appears to have given a direction of the public
mind towards chemical and philosophical inquiries, which cannot
fail in its consequences to produce the improvement of the
sciences, arts, and manufactures in Ireland. That Mr. Davy be
requested to accept the sum of five hundred guineas from the
Society.”

From Mr. Hare’s “Life and Letters of Maria Edgeworth” we gain some further information of the manner in which these lectures were received. In a letter to her cousin, Miss Ruxton, Miss Edgeworth writes:

“We are to set out for Dublin on the 13th [November] to hear
Davy’s lectures.”

Mrs. Edgeworth adds:

“We spent a few weeks in Dublin. Davy’s lectures not only opened
a new world of knowledge to ourselves and to our young people,
but were especially gratifying to Mr. Edgeworth and Maria,
confirming, by the eloquence, ingenuity, and philosophy which
they displayed, the high idea which they had so early formed of
Mr. Davy’s powers.”

Additional evidence of his success is seen in the circumstance that the Society decided to repeat their invitation:

“June 13th, 1811. _Resolved_--That a letter be written to Mr.
Professor Davy requesting him to favour the Dublin Society and
the Irish public with a further communication of the recent
discoveries in chemical philosophy, and to deliver a course of
lectures in their laboratory for that purpose, in the months
of November and December next; and requesting that he will
also repeat to them, at the same time, the course of lectures
in geological science which he has read this year to the Royal
Institution; and that he will be so good as to procure for the
Society copies of as many of the geological sketches referred
to in that course as he may think necessary for the elucidation
of the subject; and further requesting him to superintend the
construction of a voltaic battery of large plates, for the use
of the Society, to be transmitted to them in time for these
lectures.”

We next read:

“December 5th, 1811. _Resolved unanimously_--That the thanks of
the Society be communicated to Mr. Davy, for the two excellent
courses of lectures in chemical and geological science which,
at their request, he has delivered in their laboratory, full of
valuable information; and which have not merely continued, but
materially increased, the spirit of philosophical research in
Ireland.

“_Resolved unanimously_--That Mr. Davy be requested to accept the
sum of £750 as a remuneration on the part of the Society.”

On the occasion of his second visit Trinity College, Dublin, conferred on him the degree of LL.D. It was the only mark of distinction he ever received from any University. Before he gave his lectures he visited Edgeworthstown, as we learn in a letter from Maria to Miss Ruxton:

“Davy spent a day here last week, and was as usual full of
entertainment and information of various kinds. He has gone to
Connemara, I believe, to fish, for he is a little mad about
fishing; and very ungrateful it is of me to say so, for he sent
to us from Boyle the finest trout! and a trout of Davy’s catching
is, I presume, worth ten trouts caught by vulgar mortals.”

To his mother he writes:

“Ballina, Ireland, _October 24th_.

“MY DEAR MOTHER,--I am safe and well, in a remote and beautiful
part of Ireland, where I have been making an excursion with two
of my friends. I shall return to Dublin in two or three days, and
shall be very glad to hear from you or my sisters there. I hope
you are all well and happy.

“I heard from John a few days ago; he was quite well and in good
spirits.

“The laboratory in Dublin, which has been enlarged so as to hold
550 people, will not hold half the persons who desire to attend
my lectures. The 550 tickets issued for the course by the Dublin
Society, at two guineas each, were all disposed of the first
week; and I am told now that from ten to twenty guineas are
offered for a ticket.

“This is merely for your eye; it may please you to know that your
son is not unpopular or useless. Every person here, from the
highest to the lowest, shows me every attention and kindness.

“I shall come to see you as soon as I can. I hear with infinite
delight of your health, and I hope Heaven will continue to
preserve and bless a mother who deserves so well of her children.

“I am your very affectionate son
“H. DAVY.

“My kindest love to my sisters and aunts.”

But Davy’s affections at the moment were not wholly spent upon his kindred, and another mistress than Science had become the object of his devotion. The “little madness” of which Maria Edgeworth wrote was always a vulnerable point with Davy, for he followed the calling of the Apostles with all the zeal and ardour he gave to philosophy, and to engage him upon the subject of angling was a more direct road to his sympathies than to talk to him of science.

The wooing began in this wise:

“Mr. Davy regrets that he cannot send Walton to Mrs. Apreece
this morning. He did not recollect that he had lent the book to
a friend who lives a little way out of town. He will send honest
Isaac to Mrs. Apreece to-morrow or Thursday.

“Mrs. Apreece is already of the true faith of the genuine angler,
the object of whose art and contemplation is to exalt spirit
above matter, to enable the mind to create its own enjoyments and
to find society even in the bosom of Nature.”

Matters went on apace. Shortly afterwards we read:

“I return the ticket. I begin to like the opera from association.
The same association would, I think, make me love a desert, and
perhaps, in a long time, might make me an admirer of routs.”

Again:

“To avoid studiously what other people seek would have the
semblance of affectation and though sincerely I have no ambition
to shine in courts or to become a courtier; yet I have sympathy
more than enough to wish to be where you like to go.”

On another occasion he wrote:

“I find an invitation from Mr. T---- on my return last night for
Wednesday. Pray do you go to the Miss Ch----’s to-night or to
Miss S----’s to-morrow night? I wish to know as you are my magnet
(though you differ from a magnet in having no repulsive point)
and direct my course. Your society always delightful to me is
really at this moment balm to a wounded mind.”

The following is a New Year’s Day letter written to arrive on January 1st, 1812:--

“I hope the cold weather has not increased your indisposition and
that the foggy sky has not made you melancholy. I trust you are
now well and happy: I give myself pleasure by believing that you
are.

“I have a motive for writing this day besides that of doing what
I like. I find that Friday the 10th is a Royal Society Club day
and that I ought to dine with the Club. All other days are yours
and _that_ shall be yours if you command it, but I know you wish
me to do what I _ought_ to do, and you _now_ cannot doubt the
exclusive nature of your influence and the absolute nature of
your power.

“I spent the last two days very pleasantly at Wilderness, Lord
Camden’s; there was a very agreeable social party and a Christmas
country ball: a fine park had lost its beauty from the old age
of the year and everything was white; the circle round the fire
had in consequence more charms and my friend and I left it this
morning very well amused.

“To-day we celebrate the old Mr. Children’s birthday who is 70.
He bears his years healthfully and joyfully. Such winter’s days
as his are rather to be desired than feared--sunny, calm and warm.

“I hope, my darling friend, that you bear no uneasiness in your
kind and good heart and that you give its true meaning to my
unlucky sentence. Indeed I never in the whole course of our
social converse ever intended to offend you or give you a moment
of uneasiness and I do not think I should feel anything _long
painful_ that I thought would promote your happiness even though
it should require from me the greatest of all sacrifices. You
know what this is and I trust you will never oblige me to make it.

“I go on Thursday to a wild part of Kent to shoot pheasants: the
house is Mr. Hodges, the post-town Cranbrook. I shall accompany
Children to town on Sunday; and I hope you will permit me to see
you that evening if I come in time, or Monday morning. I am going
on steadily for three hours a day with Radiant Heat and Light. I
might petition for one of your distant beams of light. You know
it would delight me; but whether it comes or no you shall not
cease to be my sun.”

These letters, with many others addressed by him to the lady, are now before me. They had been carefully tied up and preserved, and are all dated by her on the back--even down to the little missives sent across from Albemarle Street to Berkeley Square, where she resided. From the number and frequency of these it is evident that the porter suffered from no lack of exercise. After her death in 1855 these letters came into the possession of Dr. John Davy, together with other papers, and some have been published already in his “Fragmentary Remains.” The correspondence is of especial interest from the sidelight it throws on Davy’s disposition and character. Many of the letters are delightful in tone and feeling; not even Amadis de Gaul, that cream and flower of gentility, or that mirror of chivalry, the Knight of the Woful Figure, could have been more courteous in bearing, or have shown a warmer and at the same time a more deferential admiration of the lady he wooed. But the world, after all, has no concern with their tender confidences. It is sufficient to say that Davy’s letters are such as might be expected from his ardent temperament and active imagination; from his love of natural scenery, his faculty of happy expression, and graphic power of description.

Early in 1812 Sir Joseph Banks, whose constant thought was of and for the Royal Society, thus wrote to his friend Sir George Stanton:--

“The Royal Society has been well supplied with papers, and
continues to be so. Davy, our secretary, is said to be on the
point of marrying a rich and handsome widow, who has fallen in
love with Science and marries him in order to obtain a footing
in the Academic Groves; her name is Apreece, the daughter of Mr.
Carr, [Kerr] who made a fortune in India, and the niece of Dr.
Carr, [Kerr] of Northampton. If this takes place, it will give
to science a kind of new _éclat_; we want nothing so much as the
countenance of the ladies to increase our popularity.”

The lady was the widow of Shuckburgh Ashby Apreece, the eldest son of Sir Thomas Apreece; she was the daughter and heiress of Charles Kerr of Kelso, who had been secretary to Lord Rodney, and had made a fortune in the West Indies. She was also a “far-away cousin” of Sir Walter Scott, and on the occasion of his tour in the Hebrides with his family, “his dear friend and distant relation,” as he calls her, accompanied them. She had been, he says, “a lioness of the first magnitude in Edinburgh” during the preceding winter; and in one of his letters to Byron in 1812, inviting him to Abbotsford, he mentions as one of the visitors that would make his house attractive “the fair or shall I say the sage Apreece that was, Lady Davy that is, who is soon to show us how much science she leads captive in Sir Humphry; so your lordship sees, as the citizen’s wife says in the farce, ‘Threadneedle Street has some charms,’ since they procure us such celebrated visitants.” How Scott regarded her is further indicated in the letters which he addressed to her on the occasion of his son’s marriage, and during the financial crash which overwhelmed him.

When the marriage was arranged Davy thus wrote to his mother:--

“MY DEAR MOTHER,--You possibly may have heard reports of my
intended marriage. Till within the last few days it was mere
report. It is I trust now a settled arrangement. I am the
happiest of men, in the hope of a union with a woman equally
distinguished for virtues, talents and accomplishments....

“You, I am sure, will sympathise in my happiness. I believe I
should never have married, but for this charming woman, whose
views and whose tastes coincide with my own, and who is eminently
qualified to promote my best efforts and objects in life....

“I am your affectionate son,
“H. DAVY.”

In the following letter to Dr. John Davy, who was then in Edinburgh as a student of medicine, we have also the announcement of another event:--

“Friday, _April 10th, 1812_.

“MY DEAR BROTHER,--You will have excused me for not writing to
you on subjects of science. I have been absorbed by arrangements
on which the happiness of my future life depends. Before you
receive this these arrangements will, I trust, be settled; and,
in a few weeks, I shall be able to return to my habits of study
and of scientific research.

“I am going to be married to-morrow; and I have a fair prospect
of happiness, with the most amiable and intellectual woman I have
ever known.

“The Prince Regent, unsolicited by me, or by any of my intimate
friends, was pleased to confer the honour of knighthood on me at
the last _levée_. This distinction has not often been bestowed on
scientific men; but I am proud of it, as the greatest of human
geniuses bore it; and it is at least a proof that the court has
not overlooked my humble efforts in the cause of science.

“I have discovered pure phosphorous acid (a solid body, very
volatile); and a pure hydro-phosphorous acid, containing
two proportions of water and four of phosphorous acid, and
decomposing by heat into phosphoric acid and a new gas containing
four proportions of hydrogen and one of phosphorus....

“Pray address to me Sir H. Davy, Beechwood Park, near Market St.
Alban’s.

“Believe me, my dear John, I shall always take the warmest
interest in your welfare and happiness, and will do everything to
promote your views. I shall have some ideas on your studies soon
to communicate.

“I am, my dear brother most affectionately yours
“H. DAVY.”

He was knighted by the Prince Regent at a _levée_ held at Carlton House on the 8th April, 1812, being the first person on whom that honour was conferred by the Regent. On the following day he delivered his farewell lecture as Professor of Chemistry at the Royal Institution. It was on the Metals, and a report of it is contained in Faraday’s manuscript notes before referred to. Faraday says:--

“Having thus given the general character of the metals, Sir H.
Davy proceeded to make a few observations on the connection
of science with the other parts of polished and social life.
Here it would be improper for me to follow him. I should merely
injure and destroy the beautiful, the sublime observations
that fell from his lips. He spoke in the most energetic and
luminous manner of the advancement of the arts and sciences, of
the connection that had always existed between them and other
parts of a nation’s economy. He noticed the peculiar congeries
of great men in all departments of life that generally appeared
together, noticed Anaximander, Anaximenes, Socrates, Newton,
Bacon, Elizabeth, etc., but, by an unaccountable omission, forgot
himself, though I venture to say no one else present did.

“During the whole of these observations his delivery was easy,
his diction elegant, his tone good, and his sentiments sublime.”

Two days afterwards he was married, and Lady Davy and he passed most of the spring and summer in the North of England and in Scotland, on a round of visits, cultivating those patrician instincts and susceptibilities to the charms of rank that his new station served to accentuate.

Writing to Miss Margaret Ruxton, Maria Edgeworth says:--

“I suppose you have heard various _jeux d’esprit_ on the marriage
of Sir Humphry Davy and Mrs. Apreece? I scarcely think any of
them worth copying.”

But she gives the following:--

“Too many men have often seen
Their talents underrated;
But Davy owns that his have been
Duly _Apreeciated_.”

Shortly after his wedding he wrote to his brother John:--

“I communicated to you in a former letter, my plans, as they
were matured. I have neither given up the Institution, nor am I
going to France; and, wherever I am, I shall continue to labour
in the cause of science with a zeal not diminished by increase of
happiness and (with respect to the world) increased independence.

“I have just finished the first part of my ‘Chemistry’ to my
own satisfaction, and I am going to publish my ‘Agricultural
Lectures’ for which I am to get 1,000 guineas for the copyright
and 50 guineas for each edition, which seems a fair price....

“I was appointed Professor (honorary) to the Institution, at the
last meeting. I do not pledge myself to give lectures.... If
I lecture it will be on some new series of discoveries, should
it be my fortune to make them; and I give up the _routine_ of
lecturing, merely that I may have more time to pursue original
inquiries, and forward more the great objects of science. This
has been for some time my intention, and it has been hastened by
my marriage.

“I shall have great pleasure in making you acquainted with Lady
D. She is a noble creature (if I may be permitted so to speak
of a wife), and every day adds to my contentment by the powers
of her understanding, and her amiable and delightful tones of
feeling.”

The allusion to the Institution is thus more circumstantially dealt with in the following Minutes of the Meetings of the Managers:--

“_May 11, 1812._ Mr. Hatchett reported that Sir H. Davy, though
he cannot pledge himself to deliver lectures, will be willing to
accept the offices of Professor of Chemistry and Director of the
Laboratory and Mineralogical Collection without salary.”

Following which we read--

“That the Managers hear with great regret the notification which
they have just received that Sir H. Davy cannot pledge himself
to continue the lectures which he has been accustomed to deliver
with so much honour to the Institution and advantage to the
public; but at the same time, they congratulate themselves on the
liberal offer which Sir Humphry Davy has made to superintend the
chemical department, and to assist and advise any lecturer the
Managers may be pleased to appoint.”

The Managers thereupon ordered a special general meeting to nominate him Professor of Chemistry, and he was elected on June 1st. How necessary Davy was to the very existence of the Institution may be gleaned from the fact that the balance in its favour at the end of the year was £3 9s. 11d.

The “Chemistry” above referred to is his “Elements of Chemical Philosophy,” which was published a few months after his marriage, with a dedication to Lady Davy. She is asked to receive it as a proof of his ardent affection, which must be unalterable, as it is founded upon the admiration of her moral and intellectual qualities. The work was begun in the autumn of 1811, and was composed with great rapidity, the “copy” being sent to the press as it left his pen. The introductory part on the History of Chemistry, and that on the General Laws of Chemical Changes and on Radiant or Ethereal Matter, and probably some other portions, are either transcripts or amplifications of his Royal Institution lectures. Other sections are avowedly based upon his own work as published in the _Philosophical Transactions_. Indeed, it was remarked by a critic that the work could never be completed upon the plan on which it was commenced, which was little less than a system of chemistry in which all the facts were to be verified by the author.

Thomas Young, his former colleague at the Royal Institution, in the _Quarterly Review_ for September, 1812, thus speaks of it:--

“With all its excellencies this work must be allowed to bear
no inconsiderable marks of haste, and we would easily have
conjectured, even if the author had not expressly told us so
in his dedication, that the period employed on it has been the
‘happiest of his life’....

“The style and manner of this work are nearly the same with
those of the author’s lectures delivered in the theatre of the
Royal Institution. They have been much admired by some of the
most competent judges of good language and good taste, and it
has been remarked that Davy was born a poet, and has only become
a chemist by accident. Certainly the situation in which he was
placed induced him to cultivate an ornamented and popular style
of expression and embellishment, and what was encouraged by
temporary motives has become natural to him from habit. Hence
have arisen a multitude of sentimental reflections and appeals
to the feelings, which many will think beauties and some only
prettinesses; nor is it necessary for us to decide in which of
the two classes of readers we wish ourselves to be arranged,
conceiving that in matters so indifferent to the immediate object
of the work a great latitude may be allowed to the diversity of
taste and opinion.”

Despite its egoism and the obvious marks of haste and imperfection it displays, the work may still be read with interest by the chemical student. We would recommend him before perusing it to study Dalton’s “New System of Chemical Philosophy,” and he will gain a vivid impression of the extraordinary strides which the science had made during the four years which intervened between the publication of these memorable books. Each work, too, is strongly typical of its author, and reflects in the most striking manner the range and limitations of his powers and the characteristics of his genius.

Towards the middle of October Davy returned to town. In a letter written to his friend Children, from Edinburgh, he says:--

“I have received a very interesting letter from Ampère. He says
that a combination of chlorine and azote has been discovered at
Paris, which is a fluid, and explodes by the heat of the hand;
the discovery of which cost an eye and a finger to the author.
He gives no details as to the mode of combining them. I have
tried in my little apparatus with ammonia cooled very low, and
chlorine, but without success.”

The substance here referred to is nitrogen chloride, one of the most formidable explosives known to chemists, and which seriously maimed Dulong, its discoverer, as stated. The “little apparatus” refers to a portable chemical chest which accompanied Davy on all his travels. Any new combination of nitrogen was certain to attract his immediate attention. He seems to have remained to the last convinced that nitrogen would turn out to be a non-elementary substance, and it is remarkable how eagerly he caught at any hint or surmise which appeared likely to afford support to his conjecture. He at once repeated Dulong’s experiments in Children’s laboratory at Tunbridge, and succeeded in obtaining considerable information concerning the chemical and physical properties of this extraordinary substance, when he was wounded in the eye by its explosion.

He thus breaks the news of his accident to Lady Davy:--

“... Yesterday I began some new experiments to which a very
interesting discovery and a slight accident put an end. I made
use of a compound more powerful than gunpowder destined perhaps
at some time to change the nature of war and influence the
state of society. An explosion took place which has done me no
other harm than that of preventing me from working this day
[Sunday] and the effects of which will be gone to-morrow and
which I should not mention at all, except that you may hear some
foolish exaggerated account of it, for it really is not worth
mentioning....”

In reality the accident was more serious than he would have Lady Davy believe, and the injury prevented him from resuming his work for some time.

In a letter written about the middle of January, 1813, from Wimpole, where he was staying with Lord Hardwicke, he says:--

“I have had another severe attack of inflammation in the eye,
and was obliged to have the conjunctiva and cornea punctured. I
suspect the cause was some little imperceptible fragment. I am
just recovering, and hope I shall see as well soon as with the
other eye.”

In the following April he was sufficiently recovered to resume the study of Dulong’s compound, and in a letter to Sir Joseph Banks, dated June 20th, 1813, and subsequently published in the _Philosophical Transactions_, he gives a number of details concerning its nature and composition. He accurately determined its specific gravity--viz. 1·653--but although he made a number of determinations of the amounts of its constituents by various methods, his deduction that it consisted of one proportion of nitrogen to four of chlorine was incorrect. The experiments of Gattermann, made with great skill and courage, have conclusively shown that the compound is, as long surmised, a trichloride of nitrogen.

At about the same period, as we learn from a letter to his brother, dated April 4th, 1813, he attacked the chemistry of fluorine:--

“I am now quite recovered, and Jane [Lady Davy] is very well, and
we have both enjoyed the last month in London. I have been hard
at work. I have expelled fluorine from fluate of lead, fluate of
silver, and fluate of soda by chlorine. It is a new acidifier,
forming three powerful acids; hydrofluoric, silicated fluoric,
and fluo-boric. It has the most intense energies of combination
of any known body, instantly combining with all metals, and
decomposing glass. Like the fabled waters of the Styx, it cannot
be preserved, not even in the ape’s hoof. We have now a triad of
supporters of combustion.”

The results of Davy’s work were communicated to the Royal Society on July 8th, 1813. In his paper he states that M. Ampère of Paris had furnished him with many ingenious and original arguments in favour of the analogy between the muriatic and fluoric compounds, based partly upon his (Davy’s) views of the nature of chlorine, and partly upon reasonings drawn from the experiments of Gay Lussac and Thenard. After a short account of the main properties of the silicated fluoric acid gas (silicon fluoride), discovered by Scheele, fluoric acid (hydrofluoric acid), discovered by Scheele but first obtained pure by Gay Lussac and Thenard, and fluoric acid (boron fluoride), discovered by Gay Lussac and Thenard, he states that, on the hypothesis of M. Ampère--

“the silicated fluoric acid is conceived to consist of a peculiar
undecompounded principle, analogous to chlorine and oxygen,
united to the basis of silica, or _silicum_; the fluo-boric
acid of the same principle united to boron; and the pure liquid
fluoric acid as this principle united to hydrogen,”

He then seeks to put the hypothesis to the test of experiment by combining fluoric acid with ammonia in a platinum apparatus; the white solid substance he obtained--so-called fluate of ammonia--contained no moisture, and hence he inferred that no water was present and that therefore fluoric acid was free from oxygen. The inference was more correct than the experiment warranted. He further found that the action of potassium upon fluate of ammonia is precisely similar to its action upon muriate of ammonia, when ammonia and hydrogen are disengaged and muriate of potassa formed. He then attempted to electrolyse solutions of hydrofluoric acid. He says:

“I undertook the experiment of electrizing pure liquid fluoric
acid, with considerable interest, as it seemed to offer the most
probable method of ascertaining its real nature; but considerable
difficulties occurred in executing the process. The liquid
fluoric acid immediately destroys glass, and all animal and
vegetable substances; it acts on all bodies containing metallic
oxides; and I know of no substances which are not rapidly
dissolved or decomposed by it except [certain] metals, charcoal,
phosphorus, sulphur and certain combinations of chlorine.”

After various unsuccessful attempts to make tubes of sulphur and of the chlorides of lead and copper, he succeeded

“in boring a piece of horn-silver in such a manner that I was
able to cement a platina wire into it by means of a spirit lamp,
and by inverting this in a tray of platina filled with liquid
fluoric acid, I contrived to submit the fluid to the agency of
electricity.”

He found that the platina wire at the positive pole rapidly corroded, and became covered with a chocolate powder, and what appeared by its inflammability to be hydrogen separated at the negative pole. He tried a number of other experiments with different vessels and various electrodes, but with no better success.

He suffered great inconvenience from the fumes of hydrofluoric acid; they acted vigorously on the nails, and produced a most painful sensation when in contact with the eyes. The conclusion he drew from his experiments was that fluoric acid is “composed of hydrogen, and a substance as yet unknown in a separate form, possessed like oxygen and chlorine, of the negative electrical energy, and hence determined to the positive surface, and strongly attracted by metallic substances.”

He then attempted to isolate the fluoric principle by treating various fluates in a platinum apparatus with chlorine gas, but although there was evidence of decomposition and the platinum was violently acted upon, he could obtain no new gaseous matter.

“From the general tenour of the results that I have stated, it
appears reasonable to conclude that there exists in the fluoric
compounds a peculiar substance, possessed of strong attractions
for metallic bodies and hydrogen, and which combined with certain
inflammable bodies forms peculiar acids, and which in consequence
of its strong affinities and high decomposing agencies, it will
be very difficult to examine in a pure form, and for the sake of
avoiding circumlocution, it may be denominated _fluorine_, a name
suggested to me by M. Ampère.

“It is easy to perceive in following the above theory, that all
the ideas current in chemical authors respecting the fluoric
combinations, must be changed. Fluor-spar, and other analogous
substances, for instance, must be regarded as binary compounds of
metals and fluorine.”

Davy’s views are now part of current chemical doctrine, and his previsions as to the nature of fluorine and its extraordinary chemical activity have been verified in the most striking manner by the admirable investigations of Moissan.