“THE SCEPTICAL CHEMIST”: THE DAWN OF SCIENTIFIC CHEMISTRY.
The latter half of the seventeenth century was a remarkable period
in the history of the intellectual development of Europe. At that
time nearly every department of human knowledge seemed to have become
permeated by an eager spirit of scepticism, inquiry, and reform.
The foundation of the Royal Society of London for Improving Natural
Knowledge, the Accademia del Cimento of Florence, the Academie Royale
at Paris, the Berlin Academy, all within a few years of each other,
was significant of the times. Chemistry was no longer to be a sacred
mystery, to be known only to priests, and its secrets jealously
guarded by them. Science had chafed under the domination of the
schoolmen; it was now contemptuous of the dialectics of the Spagyrists.
Experimentarian philosophy became even fashionable; and the purely
deductive methods of the Peripatetics gradually gave place to the only
sound method of advancing natural knowledge. The supremacy of the
old philosophy may be said to have been first distinctly challenged
by Robert Boyle. The appearance in 1661 of his book, _The Sceptical
Chemist_, marks a turning-point in the history of chemistry. The
“Chemico-physical Doubts and Paradoxes” raised by Boyle “touching the
experiments whereby vulgar Spagyrists are wont to endeavour to evince
their Salt, Sulphur, and Mercury to be the true Principles of Things,”
eventually sealed the fate of the doctrine of the _tria prima_, and of
the tenets of the school of Paracelsus.
In this treatise Boyle sets out to prove that the number of the
peripatetic elements or principles hitherto assumed by chemists is, to
say the least, doubtful. The words “element” and “principle” are used
by him as equivalent terms, and signify those primitive and simple
bodies of which compounds may be said to be composed, and into which
these compounds are ultimately resolvable. He considered that the
matter of all bodies was originally divided into small particles of
different shapes and sizes, and that these particles might unite into
small “parcels,” not easily separable again; that a great variety of
compounds may arise from a few ingredients; that various substances are
obtainable from bodies by fire; that fire is not the true and genuine
analyser of bodies, since it does not separate the principles of a
body, but variously alters its nature; and that some things obtained
from a body by fire were not its proper or essential ingredients.
Three is not precisely and universally the number of the distinct
substances or elements into which all compound bodies are resolvable
by fire, inasmuch as some bodies afford more than three principles.
Earth and water are as much chemical principles as salt, sulphur, and
mercury. Even the limitation to five chemical principles is too narrow.
Such is proved to be the case by the mode in which bodies, animals
and vegetable, grow, and by the analysis of minerals and metals. The
chemical theory of “qualities” of the Spagyrists is narrow, defective,
and uncertain; supposes things not proved; is often superfluous, and
frequently contradicts the phenomena of nature. The “principles” found
in bodies cannot be the cause of their qualities, since contrary
qualities are ascribed to the same body. He concludes, therefore, that
the Paracelsian elements—their “salt,” “sulphur,” and “mercury”—are not
the first and most simple principles of bodies; but that these consist,
at most, of concretions of corpuscles or particles more simple than
they, and possessing the radical and universal properties of volume,
shape, and motion.
[Illustration: ROBERT BOYLE.
From a painting by F. Kerseboom in the possession of the Royal Society.]
=Robert Boyle=, fourteenth child and the seventh and youngest son of
Richard the “Great” Earl of Cork, and Lord High Chancellor of Ireland,
was born at Lismore in 1626. He was educated at Eton under Sir Henry
Wotton, and, after spending some years on the Continent, settled at
Stalbridge in Dorset, where he owned a manor. He became a member of
what was known as the Invisible College, a small association of men
interested in the new philosophy, who met at each other’s houses in
London, and occasionally at Gresham College, “to discourse and consider
of philosophical inquiries and such as related thereunto.” The meetings
were subsequently held in Oxford, and Boyle took up his residence there
in 1654. Here—in association with Wilkins; John Wallis and Seth Ward,
the two Savilian Professors of Geometry and Astronomy; Thomas Willis,
the physician, then student of Christ Church; Christopher Wren, then
Fellow of All Souls’ College; Goddard, Warden of Merton; and Ralph
Bathurst, Fellow of Trinity, and afterwards its President—they sought
to cultivate the new philosophy, “being satisfied that there was no
certain way of arriving at any competent knowledge unless they made a
variety of experiments upon natural bodies. In order to discover what
phenomena they would produce, they pursued that method by themselves
with great industry, and then communicated their discoveries to each
other.” The Invisible College eventually grew into the Royal Society,
which received its charter in 1663. Boyle removed to London in 1668,
and died there on December 31st, 1691, in the sixty-fifth year of his
age.
A man of integrity, modest, simple, and unassuming, Boyle was an
assiduous and true student of science, and practically the whole of
his life was given to its pursuit. His social position, his example,
the purity of his private life, and the fame of his discoveries made
his personal influence very considerable, to the great advantage of
science in this country. His experimental work was of a high order.
He introduced the air-pump into England, and his “pneumatical engine”
enabled him to discover many of the fundamental properties of a gas,
notably the relation of its volume to pressure. He also discovered
the dependence of the boiling point of a liquid upon atmospheric
pressure, explained the action of the syphon, the effect of the air
on the vibration of a pendulum and on the propagation of sound, and
made experiments on the nature of flame, and on the relation of air to
combustion and respiration. In his _History of Fluidity_ he seeks to
show that a body seems to be fluid by consisting of corpuscles touching
one another only in some parts of their surfaces; whence, by reason of
the numerous spaces between them, they easily glide along each other
till they meet with some resisting body to whose internal surface they
exquisitely accommodate themselves. He considers the requisites of
fluidity to be chiefly these: The smallness of the component particles,
their determinate figure, the vacant spaces between them, and the fact
of their being agitated variously and apart by their own innate motion
or by some thinner substance which tosses them about in its passage
through them. His published works contain many well-authenticated
chemical facts, which are commonly held to be the discovery of a
later time. He prepared acetone by the distillation of the acetates
of lead and lime; and he isolated methyl alcohol from the products of
the destructive distillation of wood. He was one of the earliest to
insist on the necessity of studying the forms of crystals. He saw in
their formation proof that the internal motions, configuration, and
position of the integral parts are all that is necessary to account for
alterations and diversities in outward character. Some of the stock
illustrations of our lecture-rooms were of his contrivance. Thus he
illustrated the expansive power of freezing water by bursting a plugged
gun-barrel filled with water by solidifying the water by means of a
mixture of snow and salt—a freezing mixture which he first introduced.
Boyle was the first to formulate our present conception of an element
in contradistinction to that of the Greeks and the schoolmen who
influenced the theories of the iatro-chemists. In the sense understood
by him, the Aristotelian elements were not true elements, nor were the
salt, sulphur, and mercury of the school of Paracelsus. He was also
the first to define the relation of an element to a compound, and to
draw the distinction we still make between compounds and mixtures. He
revived the atomic hypothesis, and explained chemical combination on
the basis of affinity. He contended that one of the main objects of
the chemist was to ascertain the nature of compounds; and thereby he
stimulated the application of analysis to chemistry. Boyle discovered a
number of qualitative reactions, and applied them to the detection of
substances, either free or in combination.
But Boyle’s greatest service to learning consisted in the new spirit
he introduced into chemistry. Henceforward chemistry was no longer
the mere helpmeet of medicine. She became an independent science, the
principles of which were to be ascertained by experiment; a science
to be studied with the object of discovering the laws regulating the
phenomena with which it is concerned—and hence elucidating truth for
truth’s sake. The old philosophy of the Greeks had, as we have seen,
become merged into the doctrine of the iatro-chemists; and this was now
to be purified from the theosophical mysticism with which Paracelsus
and his followers had enshrouded it. “The dialectical subtleties of
the schoolmen much more,” says Boyle, “declare the wit of him that
uses them than increase the knowledge or remove the doubts of sober
lovers of truth.... For in such speculative inquiries where the naked
knowledge of the truth is the thing principally aimed at, what does
he teach me worth thanks, that does not, if he can, make his notion
intelligible to me, but by mystical terms and ambiguous phrases darkens
what he should clear up, and makes me add the trouble of guessing at
the sense of what he equivocally expresses, to that of learning the
truth of what he seems to deliver.” The influence of the new spirit
thus infused into the science by Boyle is seen in the general style
of chemical literature at the end of the seventeenth century, when
compared with that of the close of the sixteenth. The mysticism and
obscurity of the alchemists were no longer tolerated.
Boyle was slender and tall, with a countenance pale and emaciated.
His constitution was delicate and his body feeble, and it was only
by strict attention to diet and regularity of exercise that he
accomplished what he did. Although he suffered occasionally from an
excessive lowness of spirits, there was nothing morose or ascetic
in his nature. He was never married, although, says his friend John
Evelyn, “few men were more facetious and agreeable in conversation with
the ladies whenever he happened to be engaged among them.”
Kindly, courteous, charitable; unaffected, and temperate in his
manner of life, Boyle enjoyed the respect and esteem of all his
contemporaries. It was said of him that he was never known to have
offended any person in his whole life by any part of his deportment.
He allowed himself a great deal of decent cheerfulness, and had about
him all the tenderness of good nature, as well as all the softness of
friendship. These gave him a large share of other men’s concerns, for
he had a quick sense of the miseries of mankind. Although a philosopher
in the broadest sense of that term, his peculiar and favourite study
was chemistry, “in which,” says Bishop Burnet, “he engaged with none
of those ravenous and ambitious designs that drew many into them. His
design was only to find out nature, to see into what principles things
might be resolved, and of what they were compounded.”
=John Kunkel=, born in 1630, was the son of an alchemist attached
to the Court of the Duke of Holstein. After serving his father for
some years, he obtained employment as chemist and pharmacist under
the Dukes Charles and Henry, of Lauenburg. He subsequently entered
the laboratory at Dresden of John George II., Elector of Saxony,
and, after teaching chemistry at the University of Wittenburg, then
famous as a medical school, he accepted an invitation to take charge
of the glass works and laboratory of the Elector of Brandenburg, at
Berlin. The laboratory was burnt down, and then Charles XI. of Sweden
called him to Stockholm and ennobled him as Baron von Lowenstiern. He
died in Stockholm in 1702. Kunkel’s chief work is his _Laboratorium
Chymicum_, published after his death. It was written in German. In
it Kunkel relates how he acquired possession of a knowledge of the
manufacture of Baldwin’s phosphorus, and of the phosphorus discovered
by Brand—perhaps the most important, as it certainly was one of the
most striking, of the chemical discoveries of the seventeenth century.
Kunkel did much to liberate chemical literature from the mysticism and
obscurity of alchemy. He was scornful of the theories of the adepts,
and contemptuous of their _tria prima_.
I, old man that I am, who have been occupied with chemistry for
sixty years, have never yet been able to discover their fixed
sulphur, or how it enters into the composition of metals....
Moreover, they are not agreed among themselves respecting the kind
of sulphur. The sulphur of one is not the sulphur of the other. To
that one may reply that each is at liberty to baptise his child as
he likes. I agree: you may even, if you are so disposed, call an
ass a cow; but you will never make anyone believe that your cow is
an ass.
As to the alkahest he says:—
There has been much discussion concerning this grand natural
solvent. Some derive it from the Latin—_akali est_; others from the
two German words _all geist_ (all gas); lastly, others say it is
from _alles est_ (that’s all). As to myself, I do not believe in
Van Helmont’s universal solvent. I call it by its true name—_alles
Lügen heist_, or _alles Lügen ist_ (it is all a lie).
Kunkel discovered the secret of the manufacture of aventurine glass
and of ruby glass by means of the purple of Cassius—a product from
gold first obtained by a doctor of medicine of that name in Hamburg.
He made observations on fermentation and putrefaction—recognised that
alum was a double salt (_salduplicatum_); described the present method
of repairing pure silver, and of parting gold and silver by means
of sulphuric acid. He also described the mode of preparing a number
of essential oils, detected the presence of stearopten in oils, and
discovered nitrous ether.
=John Joachim Becher=, the son of a Lutheran minister, was born at
Speyer in 1635. Owing to the death of his father and the devastation
of the family property during the Thirty Years’ War, Becher had a
hard struggle with poverty during his youth, and led a restless,
wandering life. In 1666 he was Professor of Medicine in the University
of Mayence. Subsequently he went to Munich as head of the finest
laboratory in Europe, but, quarrelling with the Chancellor of the
Bavarian Court, betook himself to Vienna. After a short stay there, he
quitted Austria for Holland, and established himself in Haarlem. Here
he proposed to the States-General to extract gold from the sand-dunes;
but, the project failing, he left for England and visited the Cornish
mines. On the invitation of the Duke of Mecklenburg-Güstrow, he
returned to Germany. Shortly afterwards (in 1682) he died, in the
forty-seventh year of his age. Becher’s name is remembered mainly in
connection with his theory of combustion, which, as we shall see,
was subsequently developed by Stahl into the theory of Phlogiston—a
generalisation which dominated chemistry until near the close of the
eighteenth century.
=John Mayow=, born in Cornwall in 1645, was a practising physician,
whose name chiefly lives by virtue of his clear recognition of the
substance or principle in the air which is concerned in combustion,
the calcination of metals, respiration, and the conversion of venous
into arterial blood. This substance, which he found to be contained in
saltpetre, he called _spiritus igno-aëreus_ or _nitro aëreust_. Mayow
died at the age of thirty-four. Had he been able to follow up his
observations, he might have influenced very materially the development
of theoretical chemistry. As it was, he was practically overlooked by
his contemporaries, and the real significance of his work was not
appreciated until long afterwards.
=Nicolas Lemery=, also born in 1645, wrote a _Cours de Chimie_, one
of the best text-books of the time, which passed through as many as
thirteen editions, and was translated into English, German, Latin,
Italian, and Spanish.
In this book he strove, as he says, to express himself clearly, and to
avoid the obscurities which were to be found in the authors who had
preceded him.
The fine imaginations of other philosophers concerning their
physical principles may elevate the spirit by their grand ideas,
but they prove nothing demonstratively. And, as chemistry is a
science of observation, it can only be based on what is palpable
and demonstrative.
Nicolas Lemery, who is not to be confounded with his son Louis, also a
chemist, made a considerable number of contributions to pharmaceutical
chemistry; and his _Pharmacopée Universelle_, _Dictionnaire Universel
des Drogues Simples_, and _Traité de l’Antimoine_ were standard works
in their day.
Lemery was at one time a Protestant, and on the revocation of the Edict
of Nantes fled to England; but, embracing Catholicism, he returned to
Paris, re-established his pharmacy, and was elected into the Academy in
1699. He died in 1715.
=William Homberg=, born in Batavia in 1652, was originally intended
for the profession of law, but, becoming attached to science, studied
botany and medicine in Padua, chemistry at Bologna and in London,
mechanics and optics at Rome, and anatomy at Leyden. In the course of
his travels he visited the mines of Germany, Hungary, Bohemia, and
Sweden. In 1682 he was invited to Paris by Colbert, and in 1691 was
made a member of the Academy and was placed by the Duke of Orleans in
charge of his laboratory—then one of the finest in Europe. Homberg
married the daughter of Dodart, the physician. She became an expert
_préparateur_, and was of great assistance to him in his experimental
inquiries. He first made known the existence of phosphorus in France,
discovered by Brand, of Hamburg, and he described the phosphorescent
salt associated with his name. He made important observations on the
saturation of alkalis by acids, and was aware that they combined in
different proportions. He was an industrious worker, and, with the
exception of Cassini, was the most active member of the Academy. He
died on September 24th, 1715.
Next to Boyle, perhaps the most active agent in emancipating chemistry
from the yoke of alchemy was Boerhaave, who, by his teaching as
Professor of Physic, raised the University of Leyden to the summit of
its fame.
=Hermann Boerhaave=, the son of a minister, was born near Leyden, in
1668. He occupied himself in turn with theology, classics, mathematics,
chemistry, and botany, when he turned to physic, and, after a course of
study at the University of Harderwyk, in Gelderland, began to practise.
In 1702 he was appointed to a lectureship, and eventually to the Chair
of Medicine, in the University of Leyden, of which he became Rector
in 1714. His reputation as a teacher spread throughout Europe, and
steadily increased until his death.
[Illustration: HERMANNUS BOERHAAVE
Medicinæ, Botanices, Chemiæ
& Collegii practici, in ACAD. LUGD. BAT.
PROFESSOR ORDINARIUS.
After a painting by T. Wandelaar]
Boerhaave was one of the most learned men of his age, and singularly
well cultured, not only in science but in history, poetry, and polite
literature. He conversed in English, French, and German, and read
Italian and Spanish with facility. “The Latin he spoke extempore in
lectures or conversation was so clear that, with his action, method,
and the aptness of his similes, he could level the most abstruse
points to the meanest capacities.”[2] He was fond of music, and a good
performer on several instruments, particularly the lute. He delighted
to welcome musicians to his house. His profession as a physician
brought him wealth, much of which he spent in horticulture; and the
garden of his country seat, nearly eight acres in extent, was enriched
with all the exotic trees he could procure and induce to flourish in
the climate of Holland.
[2] Burton, _Life of Boerhaave_, p. 58 _et seq._
Boerhaave was of a robust frame and healthy constitution, early inured
to constant exercise and the inclemencies of weather. His stature was
rather tall, and his habit corpulent. He had a large head, short neck,
florid complexion, light brown curled hair (for he did not wear a wig),
an open countenance, and resembled Socrates in the flatness of his nose
and his natural urbanity. He died at Leyden on September 23rd, 1738, in
the seventieth year of his age.
As a chemist Boerhaave is chiefly known by his _Elementa Chemia_,
published in 1732—the most complete and most luminous chemical treatise
of its time, translations of which appeared in the chief European
languages. The work is divided into three main parts. The first is
concerned with the origin and progress of the art, and with the
personal history of its most distinguished cultivators. The second and
largest part deals with the attempt to form a system of chemistry based
on such observational matter as seemed well established. The third
consists of a collection of chemical processes relating to the analysis
or decomposition of bodies, grouped under the heads of “vegetables,”
“animals,” and “fossils”—the beginnings, in fact, of subdivision of the
science into organic and inorganic chemistry.
As regards his belief in alchemy, Boerhaave was an agnostic: he neither
affirmed nor denied the possibility of transmutation. In this respect
he resembled Newton and Boyle. Boyle, indeed, was singularly cautious
and reticent in his references to alchemistic matters. As was said of
him by Shaw, he was too wise to set any bounds to nature: he was not
prone to say that every strange thing must needs be impossible, for
he saw strange things every day, and was well aware that there are
powerful forces in the world of whose laws and modes of action he knew
nothing. With that wariness which was habitual to him, he was wont to
say that “those who had seen them might better believe them than those
who had not”; and he was modest enough to suppose that Paracelsus or
Helmont might conceivably know of agents of which he was ignorant.
Boerhaave unquestionably spent much time in the study of alchemical
works, particularly those of Paracelsus and Helmont, which he
repeatedly read. The _Philosophical Transactions_ of the Royal Society
contain the results of a laborious but fruitless investigation by
him on quicksilver, which he undertook in the hope of discovering
the seminal or engendering matter which, on the old theory of the
generation of metals, was supposed to be contained in mercury.
But although, as he relates, he tortured it by “conquassation,
trituration, digestion, and by distillation, either alone or
amalgamated with lead, tin, or gold, repeating this operation to 511
or even to 877 distillations,” the mercury appeared only “rather more
bright and liquid, without any other variation in its form or virtues,
and acquired very little, if any, increase of its specific gravity.”
=Stephen Hales= (1677–1761), an ingenious divine—he held the perpetual
curacy of Teddington, and lived practically the greater part of his
life there—distinguished as a physiologist and inventor, occupied
himself in chemical pursuits, and made a number of observations on the
production of gaseous substances. His results were communicated to the
Royal Society and subsequently republished, in a collected form, under
the title of _Statical Essays_. In these experiments he used methods
very similar in principle to those subsequently employed by Priestley.
It is evident from his description of his experiments that he must
have prepared a considerable number of gaseous substances—hydrogen,
carbonic acid, carbonic oxide, sulphur dioxide, marsh gas, etc.—but he
seems to have made no systematic attempt to study their properties,
as he considered that they were simply air, modified or “tinctured”
by the presence of substances which he regarded as more or less
fortuitous. Prior to the time of Black all forms of gaseous substance
were regarded as substantially identical—in fact, as being _air_,
as understood by the Ancients—a simple elementary substance. It was
Black’s study of carbonic acid which first clearly established that
there were essentially distinct varieties of gaseous matter.