THE SCIENTIST--SIR HUMPHRY DAVY
Humphry Davy (1778-1829) was born in Cornwall, a part of England known
for its very mild climate and the combined beauty and majesty of its
scenery. On either side of the peninsula the Atlantic in varying mood
lies extended in summer sunshine, or from its shroud of mist thunders on
the black cliffs and their time-sculptured sandstones. From the
coast inland, stretch, between flowered lanes and hedges, rolling
pasture-lands of rich green made all the more vivid by the deep reddish
tint of the ploughed fields. In Penzance, then a town of about three
thousand inhabitants, and in its picturesque vicinity, the early years
of Davy's life were passed. Across the bay rose the great vision of the
guarded mount (St. Michael's) of which Milton's verse speaks. Farther to
the east lay Lizard Head, the southernmost promontory of England, and a
few miles to the north St. Ives with its sweep of sandy beach; while not
far to the west of Penzance Land's End stood sentry "'Twixt two
unbounded seas." The youthful Davy was keenly alive to the charms of his
early environment, and his genius was susceptible to the belief in
supernatural agencies native to the imaginative Celtic people among whom
he was reared. As a precocious child of five he improvised rhymes, and
as a youth set forth in excellent verse the glories of Mount's Bay:--
"There did I first rejoice that I was born
Amidst the majesty of azure seas."
Davy received what is usually called a liberal education, putting in
nine years in the Penzance and one year in the Truro Grammar School. His
best exercises were translations from the classics into English verse.
He was rather idle, fond of fishing (an enthusiasm he retained
throughout life) and shooting, and less appreciated and beloved by his
masters than by his school-fellows, who recognized his wonderful
abilities, sought his aid in their Latin compositions (as well as in the
writing of letters and valentines), and listened eagerly to his
imaginative tales of wonder and horror. Years later he wrote to his
mother: "After all, the way in which we are taught Latin and Greek does
not much influence the important structure of our minds. I consider it
fortunate that I was left much to myself when a child, and put upon no
particular plan of study, and that I enjoyed much idleness at Mr.
Coryton's school. I perhaps owe to these circumstances the little
talents that I have and their peculiar application."
When Davy was about sixteen years old, his father died, leaving the
widow and her five children, of whom Humphry was the eldest, with very
scanty provision. The mind of the youth seemed to undergo an immediate
change. He expressed his resolution (which he nobly carried out) to play
his part as son and brother. Within a few weeks he became apprenticed to
an apothecary and surgeon, and, having thus found his vocation, drew up
his own particular plan of self-education, to which he rigidly adhered.
His brother, Dr. John Davy, bears witness that the following is
transcribed from a notebook of Humphry's, bearing the date of the same
year as his apprenticeship (1795):--
1. Theology or Religion } Taught by Nature.
Ethics or Moral Virtues } by Revelation.
2. Geography.
3. My Profession--
1. Botany. 2. Pharmacy. 3. Nosology. 4. Anatomy.
5. Surgery. 6. Chemistry.
4. Logic.
5. Language, etc.
A series of essays which Davy wrote in pursuing his scheme of
self-culture proves how rapidly his mind drew away from the
superstitions which characterized the masses of the people among whom he
lived. He had as a boy been haunted by the fear of monsters and witches
in which the credulous of all classes then believed. His notebook shows
that he was now subjecting to examination the religious and political
opinions of his time. He composed essays on the immortality and
immateriality of the soul, on governments, on the credulity of mortals,
on the dependence of the thinking powers on the organization of the
body, on the ultimate end of being, on happiness, and on moral
obligation. He studied the writings of Locke, Hartley, Berkeley, Hume,
Helvetius, Condorcet, and Reid, and knew something of German philosophy.
It was not till he was nineteen that Davy entered on the experimental
study of chemistry.
Guided by the _Elements_ of Lavoisier, encouraged by the friendship of
Gregory Watt (a son of James Watt) and by another gentleman of
university education, stimulated by contact with the Cornish mining
industry, Davy pursued this new study with zeal, and within a few months
had written two essays full of daring generalizations on the physical
sciences. These were published early in 1799. Partly on the basis of the
ingenious experiment mentioned in the preceding chapter, he came to the
conclusion that "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 as a peculiar motion,
probably a vibration, of the corpuscles of bodies, tending to separate
them." Other passages might be quoted from these essays to show how the
gifted youth of nineteen anticipated the science of subsequent decades,
but in the main these early efforts were characterized by the faults of
overwrought speculation and incomplete verification. He soon regretted
the premature publication of his studies. "When I consider," he wrote,
"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."
In the mean time Davy had been chosen superintendent of the Pneumatic
Institution at Bristol by Dr. Beddoes, its founder. It was supported by
the contributions of Thomas Wedgwood and other distinguished persons,
and aimed at discovering by means of experiment the physiological effect
of inhaling different gases, or "factitious airs," as they were called.
The founding of such an establishment has been termed a scientific
aberration, but the use now made in medical practice of oxygen, nitrous
oxide, chloroform, and other inhalations bears witness to the sanity of
the sort of research there set on foot. Even before going to Bristol,
Davy had inhaled small quantities of nitrous oxide mixed with air, in
spite of the fact that this gas had been held by a medical man to be the
"principle of contagion." He now carried on a series of tests, and
finally undertook an extended experiment with the assistance of a
doctor. In an air-tight or box-chamber he inhaled great quantities of
the supposedly dangerous gas. After he had been in the box an hour and a
quarter, he respired twenty quarts of pure nitrous oxide. He described
the experience in the following 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 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
theorized, 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 endeavored to recall the ideas: they were feeble and
indistinct; one collection of terms, however, presented itself; and with
the 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!_'"
Davy aroused the admiration and interest of every one who met him. A
literary man to whom he was introduced shortly after his arrival in
Bristol spoke of the intellectual character of the young man's face. His
eye was piercing, and when he was not engaged in conversation, its
expression indicated abstraction, as though his mind were pursuing some
severe train of thought scarcely to be interrupted by external objects;
"and," this writer adds, "his ingenuousness impressed me as much as his
mental superiority." Mrs. Beddoes, a gay, witty, and elegant lady, and
an ardent admirer of the youthful scientist, was a sister of Maria
Edgeworth. The novelist's tolerance of Davy's enthusiasm soon passed
into a clear recognition of his commanding genius. Coleridge, Southey,
and other congenial friends, whom the chemist met under Dr. Beddoes'
roof, shared in the general admiration of his mental and social
qualities. Southey spoke of him as a miraculous young man, at whose
talents he could only wonder. Coleridge, when asked how Davy compared
with the cleverest men he had met on a visit to London, replied
expressively: "Why, Davy can eat them all! There is an energy, an
elasticity in his mind, which enables him to seize on and analyze all
questions, pushing them to their legitimate consequences. Every subject
in Davy's mind has the principle of vitality. Living thoughts spring up
like turf under his feet." He thought that if Davy had not been the
first chemist he would have been the first poet of the age. Their
correspondence attests the intimate interchange of ideas and sentiments
between these two men of genius, so different, yet with so much in
common.
In 1801 Davy was appointed assistant lecturer in chemistry at the Royal
Institution (Albemarle Street, London), which had been founded from
philanthropic motives by Count Rumford in 1799. Its aim was to promote
the application of science to the common purposes of life. Its founder
desired while benefiting the poor to enlist the sympathies of the
fashionable world. Davy, with a zeal for the cause of humanity and a
clear recognition of the value of a knowledge of chemistry in technical
industries and other daily occupations, lent himself readily to the
founder's plans. His success as a public expositor of science soon won
him promotion to the professorship of chemistry in the new institution,
and through his influence an interest in scientific investigation became
the vogue of London society. His popularity as a lecturer was so great
that his best friends feared that the head of the brilliant provincial
youth of twenty-two might be turned by the adulation of which he soon
became the object. "I have read," writes his brother, "copies of verses
addressed to him then, ... anonymous effusions, some of them displaying
much poetical taste as well as fervor of writing, and all showing the
influence which his appearance and manner had on the more susceptible of
his audience."
His study of the tanning industry (1801-1802) and his lectures on
agricultural chemistry (1803-1813) are indicative of the early purpose
of the Royal Institution and of Davy's lifelong inclination. The focus
of his scientific interest, however, rested on the furtherance of the
application of the electrical studies of Galvani and Volta in chemical
analysis. In a letter to the chairman of managers of the Royal
Institution Volta had in 1800 described his voltaic pile made up of a
succession of zinc and copper plates in pairs separated by a moist
conductor, and before the end of the same year Nicholson and Carlisle
had employed an electric current, produced by this newly devised
apparatus, in the decomposition of water into its elements.
In the spring of the following year the _Philosophical Magazine_ states:
"We have also to notice a course of lectures, just commenced at the
institution, on a new branch of philosophy--we mean Galvanic Phenomena.
On this interesting branch Mr. Davy (late of Bristol) gave the first
lecture on the 25th of April. He began with the history of Galvanism,
detailed the successive discoveries, and described the different methods
of accumulating influence.... He showed the effects of galvanism on the
legs of frogs, and exhibited some interesting experiments on the
galvanic effects on the solutions of metals in acids." In a paper
communicated to the Royal Society in 1806, _On Some Chemical Agencies of
Electricity_, Davy put on record the result of years of experiment. For
example, as stated by his biographer, he had connected a cup of gypsum
with one of agate by means of asbestos, and filling each with purified
water, had inserted the negative wire of the battery in the agate cup,
and the positive wire in that of the sulphate of lime. In about four
hours he had found a strong solution of lime in the agate cup, and
sulphuric acid in the cup of gypsum. On his reversing the arrangement,
and carrying on the process for a similar length of time, the sulphuric
acid appeared in the agate cup, and the solution of lime on the opposite
side. It was thus that he studied the transfer of certain of the
constituent parts of bodies by the action of electricity. "It is very
natural to suppose," says Davy, "that the repellent and attractive
energies are communicated from one particle to another particle of the
same kind, so as to establish a conducting _chain_ in the fluid. There
may be a succession of decompositions and recompositions before the
electrolysis is complete."
The publication of this paper in 1806 attracted much attention abroad,
and gained for him--in spite of the fact that England and France were
then at war--a medal awarded, under an arrangement instituted by
Napoleon a few years previously, for the best experimental work on the
subject of electricity. "Some people," said Davy, "say I ought not to
accept this prize; and there have been foolish paragraphs in the papers
to that effect; but if the two countries or governments are at war, the
men of science are not. That would, indeed, be a civil war of the worst
description: we should rather, through the instrumentality of men of
science, soften the asperities of national hostility."
In the following year Davy reported other chemical changes produced by
electricity; he had succeeded in decomposing the fixed alkalis and
discovering the elements potassium and sodium. To analyze a small piece
of pure potash slightly moist from the atmosphere, he had placed it on
an insulated platinum disk connected with the negative side of a voltaic
battery. A platinum wire connected with the positive side was brought in
contact with the upper surface of the alkali. "The potash began to fuse
at both its points of electrization." At the lower (negative) surface
small globules having a high metallic luster like quicksilver appeared,
some of which burned with explosion and flame while others remained and
became tarnished. When Davy saw these globules of a hitherto unknown
metal, he danced about the laboratory in ecstasy and for some time was
too much excited to continue his experiments.
After recovering from a very severe illness, owing in the judgment of
some to overapplication to experimental science, and in his own judgment
to a visit to Newgate Prison with the purpose of improving its sanitary
condition, Davy made an investigation of the alkaline earths. He failed
in his endeavor to obtain from these sources pure metals, but he gave
names to barium, strontium, calcium, and magnesium, conjecturing that
the alkaline earths were, like potash and soda, metallic oxides. In
addition Davy anticipated the isolation of silicon, aluminium, and
zirconium. No doubt what gave special zest to his study of the alkalis
was the hope of overthrowing the doctrine of French chemists that oxygen
was the essential element of every acid. Lavoisier had given it, indeed,
the name oxygen (acid-producer) on that supposition. Davy showed,
however, that this element is a constituent of many alkalis.
In 1810 he advanced his controversy by explaining the nature of
chlorine. Discovered long before by the indefatigable Scheele, it bore
at the beginning of the nineteenth century the name oxymuriatic acid.
Davy proved that it contained neither oxygen nor muriatic (hydrochloric)
acid (though, as we know, it forms, with hydrogen, muriatic acid). He
gave the name _chlorine_ because of the color of the gas (χλωρός, pale
green). Davy studied later the compounds of fluorine, and though unable
to isolate the element, conjectured its likeness to chlorine.
He lectured before the Dublin Society in 1810, and again in the
following year; on the occasion of his second visit receiving the degree
of LL.D. from Trinity College. He was knighted in the spring of 1812,
and was married to a handsome, intellectual, and wealthy lady. He was
appointed Honorary Professor of Chemistry at the Royal Institution. His
new independence gave him full liberty to pursue his scientific
interests. Toward the close of 1812 he writes 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 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...."
The compound on the investigation of which he was then engaged is now
known as the trichloride of nitrogen.
In the autumn of 1813 Sir Humphry and Lady Davy, accompanied by Michael
Faraday, who on Davy's recommendation had in the spring of the same year
received a post at the Royal Institution, set out, in spite of the
continuance of the war, on a Continental tour. At Paris Sir Humphry was
welcomed by the French scientists with every mark of distinction. A
substance which had been found in the ashes of seaweed two years
previously, by a soap-boiler and manufacturer of saltpeter, was
submitted to Davy for chemical examination. Until Davy's arrival in
Paris little had been done to determine its real character. On December
6 Gay-Lussac presented a brief report on the new substance, which he
named _iode_ and considered analogous to chlorine. Davy, working with
almost incredible rapidity in the presence of his rivals, was able a
week later to sketch the chief characters of this new element, now known
by the name he chose for it--_iodine_.
We have passed over his investigation of boracic acid, ammonium nitrate,
and other compounds; we can merely mention in passing his later studies
of the diamond and other forms of carbon, of the chemical constituents
of the pigments used by the ancients, his investigation of the torpedo
fish, and his anticipation of the arc light.
It seems fitting that Sir Humphry Davy should be popularly remembered
for his invention of the miner's safety-lamp. At the beginning of the
nineteenth century the development of the iron industry, the increasing
use of the steam engine and of machinery in general led to great
activity and enterprise in the working of the coal mines. Colliery
explosions of fire-damp (marsh gas) became alarmingly frequent,
especially in the north of England. The mine-owners in some cases sought
to suppress the news of fatalities. A society, however, was formed to
protect the miners from injury through gas explosions, and Davy was
asked for advice. On his return from the Continent in 1815 he applied
himself energetically to the matter. He visited the mines and analyzed
the gas. He found that fire-damp explodes only at high temperature, and
that the flame of this explosive mixture will not pass through small
apertures. A miner's lamp was therefore constructed with wire gauze
about the flame to admit air for combustion. The fire-damp entering the
gauze burned quietly inside, but could not carry a high enough
temperature through the gauze to explode the large quantity outside. To
one of the members of the philanthropic society which had appealed to
him Davy wrote: "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."
Davy was elected President of the Royal Society in 1820, and retained
that dignity till he felt compelled by ill health to relinquish it in
1827. "It was his wish," says his brother, "to have seen the Royal
Society an efficient establishment for all the great practical purposes
of science, similar to the college contemplated by Lord Bacon, and
sketched in his _New Atlantis_; having subordinate to it the Royal
Observatory at Greenwich for astronomy; the British Museum, for natural
history, in its most extensive acceptation."
Sir Humphry Davy, after a life crowded with splendid achievements, died
at Geneva in 1829 with many of his noblest dreams unfulfilled.
Fortunately in Michael Faraday, who is sometimes referred to as the
greatest of his discoveries, he had a successor who was fully adequate
to the task of furthering the various investigations that his genius had
set on foot, and who, to the majority of men of mature mind, is no less
personally interesting than the Cornish scientist, poet, and
philosopher.
REFERENCES
John Davy, _Works of Sir Humphry Davy_.
John Davy, _Fragmentary Remains, literary and scientific, of Sir
Humphry Davy, Bart._
Bence Jones, _Life and Letters of Faraday_.
John Tyndall, _Faraday as a Discoverer_.
E. v. Meyer, _History of Chemistry_.
S. P. Thompson, _Michael Faraday; his Life and Work_.
Sir Edward Thorpe, _Humphry Davy, Poet and Philosopher_.