OF THE PROGRESS OF PHILOSOPHICAL CHEMISTRY IN SWEDEN.
Though Sweden, partly in consequence of her scanty population, and the
consequent limited sale of books in that country, and partly from the
propensity of her writers to imitate the French, which has prevented
that originality in her poets and historians that is requisite for
acquiring much eminence--though Sweden, for these reasons, has never
reached a very high rank in literature; yet the case has been very
different in science. She has produced men of the very first eminence,
and has contributed more than her full share in almost every department
of science, and in none has she shone with greater lustre than in the
department of Chemistry. Even in the latter part of the seventeenth
century, before chemistry had, properly speaking, assumed the rank of a
science, we find Hierne in Sweden, whose name deserves to be mentioned
with respect. Moreover, in the earlier part of the eighteenth century,
Brandt, Scheffer, and Wallerius, had distinguished themselves by their
writings. Cronstedt, about the middle of the eighteenth century, may
be said to have laid the foundation of systematic mineralogy upon
chemical principles, by the publication of his System of Mineralogy.
But Bergman is entitled to the merit of being the first person who
prosecuted chemistry in Sweden on truly philosophical principles,
and raised it to that high estimation to which its importance justly
entitles it.
Torbern Bergman was born at Catherinberg, in West Gothland, on the
20th of March, 1735. His father, Barthold Bergman, was receiver of the
revenues of that district, and his mother, Sara Hägg, the daughter of
a Gotheborg merchant. A receiver of the revenues was at that time,
in Sweden, a post both disagreeable and hazardous. The creatures of
a party which had had the ascendancy in one diet, they were exposed
to the persecution of the diet next following, in which an opposite
party usually had the predominance. This circumstance induced Bergman
to advise his son to turn his attention to the professions of law or
divinity, which were at that time the most lucrative in Sweden. After
having spent the usual time at school, and acquired those branches of
learning commonly taught in Sweden, in the public schools and academies
to which Bergman was sent, he went to the University of Upsala, in the
autumn of 1752, where he was placed under the guidance of a relation,
whose province it was to superintend his studies, and direct them to
those pursuits that were likely to lead young Bergman to wealth and
distinction. Our young student showed at once a decided predilection
for mathematics, and those branches of physics which were connected
with mathematics, or depended upon them. But these were precisely
the branches of study which his relation was anxious to prevent his
indulging in. Bergman attempted at once to indulge his own inclination,
and to gratify the wishes of his relation. This obliged him to study
with a degree of ardour and perseverance which has few examples.
His mathematical and physical studies claimed the first share of his
attention; and, after having made such progress in them as would
alone have been sufficient to occupy the whole time of an ordinary
student--to satisfy his relation, Jonas Victorin, who was at that
time a _magister docens_ in Upsala, he thought it requisite to study
some law books besides, that he might be able to show that he had not
neglected his advice, nor abandoned the views which he had held out.
He was in the habit of rising to his studies every morning at four
o'clock, and he never went to bed till eleven at night. The first year
of his residence at Upsala, he had made himself master of Wolf's Logic,
of Wallerius's System of Chemistry, and of twelve books of Euclid's
Elements: for he had already studied the first book of that work in
the Gymnasium before he went to college. He likewise perused Keil's
Lectures on Astronomy, which at that time were considered as the best
introduction to physics and astronomy. His relative disapproved of his
mathematical and physical studies altogether; but, not being able to
put a stop to them, he interdicted the books, and left his young charge
merely the choice between law and divinity. Bergman got a small box
made, with a drawer, into which he put his mathematical and physical
books, and over this box he piled the law books which his relative had
urged him to study. At the time of the daily visits of his relative,
the mathematical and physical books were carefully locked up in the
drawer, and the law books spread upon the table; but no sooner was his
presence removed, than the drawer was opened, and the mathematical
studies resumed.
This incessant study; this necessity under which he found himself to
consult his own inclinations and those of his relative; this double
portion of labour, without time for relaxation, exercise, or amusement,
proved at last injurious to young Bergman's health. He fell ill, and
was obliged to leave the university and return home to his father's
house in a state of bad health. There constant and moderate exercise
was prescribed him, as the only means of restoring his health. That his
time here might not be altogether lost to him, he formed the plan of
making his walks subservient to the study of botany and entomology.
At this time Linnæus, after having surmounted obstacles which would
have crushed a man of ordinary energy, was in the height of his glory;
and was professor of botany and natural history in the University of
Upsala. His lectures were attended by crowds of students from every
country in Europe: he was enthusiastically admired and adored by
his students. This influence on the minds of his pupils was almost
unbounded; and at Upsala, every student was a natural historian.
Bergman had studied botany before he went to college, and he had
acquired a taste for entomology from the lectures of Linnæus himself.
Both of these pursuits he continued to follow after his return home
to West Gothland; and he made a collection of plants and of insects.
Grasses and mosses were the plants to which he turned the most of his
attention, and of which he collected the greatest number. But he felt
a predilection for the study of insects, which was a field much less
explored than the study of plants.
Among the insects which he collected were several not to be found in
the _Fauna Suecica_. Of these he sent specimens to Linnæus at Upsala,
who was delighted with the present. All of them were till then unknown
as Swedish insects, and several of them were quite new. The following
were the insects at this time collected by Bergman, and sent to Upsala,
as they were named by Linnæus:
_Phalæna._ Bombyx monacha, camelina.
Noctua Parthenias, conspicillaris.
Perspicillaris, flavicornis, Plebeia.
Geometra pennaria.
Tortrix Bergmanniana, Lediana.
Tinea Harrisella, Pedella, Punctella.
_Tenthredo._ Vitellina, ustulata.
_Ichneumon._ Jaculator niger.
_Tipula._ Tremula.
When Bergman's health was re-established, he returned to Upsala with
full liberty to prosecute his studies according to his own wishes, and
to devote the whole of his time to mathematics, physics, and natural
history. His relations, finding it in vain to combat his predilections
for these studies, thought it better to allow him to indulge them.
He had made himself known to Linnæus by the collection of insects
which he had sent him from Catherinberg; and, drawn along by the
glory with which Linnæus was surrounded, and the zeal with which his
fellow-students prosecuted such studies, he devoted a great deal of
his attention to natural history. The first paper which he wrote upon
the subject contained a discovery. There was a substance observed in
some ponds not far from Upsala, to which the name of _coccus aquaticus_
was given, but its nature was unknown. Linnæus had conjectured that
it might be the _ovarium_ of some insect; but he left the point to be
determined by future observations. Bergman ascertained that it was the
ovum of a species of leech, and that it contained from ten to twelve
young animals. When he stated what he had ascertained to Linnæus, that
great naturalist refused to believe it; but Bergman satisfied him
of the truth of his discovery by actual observation. Linnæus, thus
satisfied, wrote under the paper of Bergman, _Vidi et obstupui_, and
sent it to the academy of Stockholm with this flattering panegyric. It
was printed in the Memoirs of that learned body for 1756 (p. 199), and
was the first paper of Bergman's that was committed to the press.
He continued to prosecute the study of natural history as an amusement;
though mathematics and natural philosophy occupied by far the greatest
part of his time. Various useful papers of his, connected with
entomology, appeared from time to time in the Memoirs of the Stockholm
Academy; in particular, a paper on the history of insects which attack
fruit-trees, and on the methods of guarding against their ravages: on
the method of classing these insects from the forms of their larvæ, a
time when it would be most useful for the agriculturist to know, in
order to destroy those that are hurtful: a great number of observations
on this class of animals, so various in their shape and their
organization, and so important for man to know--some of which he has
been able to overcome, while others, defended by their small size, and
powerful by their vast numbers, still continue their ravages; and which
offer so interesting a sight to the philosopher by their labours, their
manners, and their foresight.--Bergman was fond of these pursuits,
and looked back upon them in afterlife with pleasure. Long after, he
used to mention with much satisfaction, that by the use of the method
pointed out by him, no fewer than seven millions of destructive insects
were destroyed in a single garden, and during the course of a single
summer.
About the year 1757 he was appointed tutor to the only son of Count
Adolf Frederick Stackelberg, a situation which he filled greatly to the
satisfaction both of the father and son, as long as the young count
stood in need of an instructor. He took his master's degree in 1758,
choosing for the subject of his thesis on _astronomical interpolation_.
Soon after, he was appointed _magister docens_ in natural philosophy,
a situation peculiar to the University of Upsala, and constituting a
kind of assistant to the professor. For his promotion to this situation
he was obliged to M. Ferner, who saw how well qualified he was for it,
and how beneficial his labours would be to the University of Upsala. In
1761 he was appointed _adjunct_ in mathematics and physics, which, I
presume, means that he was raised to the rank of an associate with the
professor of these branches of science. In this situation it was his
business to teach these sciences to the students of Upsala, a task for
which he was exceedingly well fitted. During this period he published
various tracts on different branches of physical science, particularly
on the _rainbow_, the crepuscula, the aurora-borealis, the electrical
phenomena of Iceland spar, and of the tourmalin. We find his name
among the astronomers who observed the first transit of Venus over the
sun, in 1761, whose results deserve the greatest confidence.[1] His
observations on the electricity of the tourmalin are important. It was
he that first established the true laws that regulate these curious
phenomena.
[1] See Phil. Trans., vol. lii. p. 227, and vol. lvi. p. 85.
During the whole of this period he had been silently studying chemistry
and mineralogy, though nobody suspected that he was engaged in any
such pursuits. But in 1767 John Gottschalk Wallerius, who had long
filled the chair of chemistry in the University of Upsala, with high
reputation, resigned his chair. Bergman immediately offered himself
as a candidate for the vacant professorship: and, to show that he
was qualified for the office, published two dissertations on the
Manufacture of Alum, which probably he had previously drawn up, and had
lying by him. Wallerius intended to resign his chair in favour of a
pupil or relation of his own, whom he had destined to succeed him. He
immediately formed a party to oppose the pretensions of Bergman; and
his party was so powerful and so malignant, that few doubted of their
success: for it was joined by all those who, despairing of equalling
the industry and reputation of Bergman, set themselves to oppose and
obstruct his success. Such men unhappily exist in all colleges, and
the more eminent a professor is, the more is he exposed to their
malignant activity. Many of those who cannot themselves rise to any
eminence, derive pleasure from the attempt to pull down the eminent
to their own level. In these attempts, however, they seldom succeed,
unless from some want of prudence and steadiness in the individual
whom they assail. Bergman's Dissertations on Alum were severely
handled by Wallerius and his party: and such was the influence of the
ex-professor, that every body thought Bergman would be crushed by him.
Fortunately, Gustavus III. of Sweden, at that time crown prince,
was chancellor of the university. He took up the cause of Bergman,
influenced, it is said, by the recommendation of Von Swab, who pledged
himself for his qualifications, and was so keen on the subject that he
pleaded his cause in person before the senate. Wallerius and his party
were of course baffled, and Bergman got the chair.
For this situation his previous studies had fitted him in a peculiar
manner. His mathematical, physical, and natural-historical knowledge,
so far from being useless, contributed to free him from prejudices, and
to emancipate him from that spirit of routine under which chemistry
had hitherto suffered. They gave to his ideas a greater degree of
precision, and made his views more correct. He saw that mathematics
and chemistry divided between them the whole extent of natural
science, and that its bounds required to be enlarged, to enable it
to embrace all the different branches of science with which it was
naturally connected, or which depended upon it. He saw the necessity
of banishing from chemistry all vague hypotheses and explanations,
and of establishing the science on the firm basis of experiment. He
was equally convinced of the necessity of reforming the nomenclature
of chemistry, and of bringing it to the same degree of precision that
characterized the language of the other branches of natural philosophy.
His first care, after getting the chair, was to make as complete a
collection as he could of mineral substances, and to arrange them in
order according to the nature of their constituents, as far as they
had been determined by experiment. To another cabinet he assigned the
Swedish minerals, ranged in a geographical manner according to the
different provinces which furnished them.
When I was at Upsala, in 1812, the first of these collections still
remained, greatly augmented by his nephew and successor, Afzelius.
But no remains existed of the geographical collection. However, there
was a very considerable collection of this kind in the apartments
of the Swedish school of mines at Stockholm, under the care of Mr.
Hjelm, which I had an opportunity of inspecting. It is not improbable
that Bergman's collection might have formed the nucleus of this. A
geographical collection of minerals, to be of much utility, should
exhibit all the different formations which exist in the kingdom: and
in a country so uniform in its nature as Sweden, the minerals of one
county are very nearly similar to those of the other counties; with
the exception of certain peculiarities derived from the mines, or from
some formations which may belong exclusively to certain parts of the
country, as, for example, the coal formations in the south corner of
Sweden, near Helsinburg, and the porphyry rocks, in Elfsdale.
Bergman attempted also to make a collection of models of the apparatus
employed in the different chemical manufactories, to be enabled to
explain these manufactures with greater clearness to his students. I
was informed by M. Ekeberg, who, in 1812, was _magister docens_ in
chemistry at Upsala, that these models were never numerous. Nor is it
likely that they should be, as Sweden cannot boast of any great number
of chemical manufactories, and as, in Bergman's time, the processes
followed in most of the chemical manufactories of Europe were kept as
secret as possible.
Thus it was Bergman's object to exhibit to his pupils specimens of all
the different substances which the earth furnishes, with the order in
which these productions are arranged on the globe--to show them the
uses made of all these different productions--how practice had preceded
theory and had succeeded in solving many chemical problems of the most
complicated nature.
His lectures are said to have been particularly valuable. He drew
around him a considerable number of pupils, who afterwards figured as
chemical discoverers themselves. Of all these Assessor Gahn, of Fahlun,
was undoubtedly the most remarkable; but Hjelm, Gadolin, the Elhuyarts,
and various other individuals, likewise distinguished themselves as
chemists.
After his appointment to the chemical chair at Upsala, the remainder
of his life passed with very little variety; his whole time was
occupied with his favourite studies, and not a year passed that he
did not publish some dissertation or other upon some more or less
important branch of chemistry. His reputation gradually extended itself
over Europe, and he was enrolled among the number of the members
of most scientific academies. Among other honourable testimonies
of the esteem in which he was held, he was elected rector of the
University of Upsala. This university is not merely a literary body,
but owns extensive estates, over which it possesses great authority,
and, having considerable control over its students, and enjoying
considerable immunities and privileges (conferred in former times as
an encouragement to learning, though, in reality, they serve only to
cramp its energies, and throw barriers in the way of its progress),
constitutes, therefore, a kind of republic in the midst of Sweden: the
professors being its chiefs. But while, in literary establishments,
all the institutions ought to have for an object to maintain peace,
and free their members from every occupation unconnected with letters,
the constitution of that university obliges its professors to attend
to things very inconsistent with their usual functions; while it
gives men of influence and ambition a desire to possess the power and
patronage, though they may not be qualified to perform the duties, of
a professor. Such temptations are very injurious to the true cause
of science; and it were to be wished, that no literary body, in any
part of the world, were possessed of such powers and privileges. When
Bergman was rector, the university was divided into two great parties,
the one consisting of the theological and law faculties, and the other
of the scientific professors. Bergman's object was to preserve peace
and agreement between these two parties, and to convince them that it
was the interest of all to unite for the good of the university and the
promotion of letters. The period of his magistracy is remarkable in the
annals of the university for the small number of deliberations, and the
little business recorded in the registers; and for the good sense and
good behaviour of the students. The students in Upsala are numerous,
and most of them are young men. They had been accustomed frequently to
brave or elude the severity of the regulations; but during Bergman's
rectorship they were restrained effectually by their respect for his
genius, and their admiration of his character and conduct.
When the reputation of Bergman was at its height, in the year 1776,
Frederick the Great of Prussia formed the wish to attach him to the
Academy of Sciences of Berlin, and made him offers of such a nature
that our professor hesitated for a short time as to whether he ought
not to accept them. His health had been injured by the assiduity
with which he had devoted himself to the double duty of teaching and
experimenting. He might look for an alleviation of his ailments, if
not a complete recovery, in the milder climate of Prussia, and he
would be able to devote himself entirely to his academical duties; but
other considerations prevented him from acceding to this proposal,
tempting as it was. The King of Sweden had been his benefactor, and it
was intimated to him that his leaving the kingdom would afflict that
monarch. This information induced him, without further hesitation,
to refuse the proposals of the King of Prussia. He requested of the
king, his master, not to make him lose the merit of his sacrifice
by augmenting his income; but to this demand the King of Sweden very
properly refused to accede.
In the year 1771, Professor Bergman married a widow lady, Margaretha
Catharina Trast, daughter of a clergyman in the neighbourhood of
Upsala. By her he had two sons; but both of them died when infants.
This lady survived her husband. The King of Sweden settled on her an
annuity of 200 rix dollars, on condition that she gave up the library
and apparatus of her late husband to the Royal Society of Upsala.
Bergman's health had been always delicate; indeed he seems never to
have completely recovered the effects of his first year's too intense
study at Upsala. He struggled on, however, with his ailments; and, by
way of relaxation, was accustomed sometimes, in summer, to repair to
the waters of Medevi--a celebrated mineral spring in Sweden, situated
near the banks of the great inland lake, Wetter. One of these visits
seems to have restored him to health for the time. But his malady
returned in 1784 with redoubled violence. He was afflicted with
hemorrhoids, and his daily loss of blood amounted to about six ounces.
This constant drain soon exhausted him, and on the 8th of July, 1784,
he died at the baths of Medevi, to which he had repaired in hopes of
again benefiting by these waters.
The different tracts which he published, as they have been enumerated
by Hjelm, who gave an interesting account of Bergman to the Stockholm
Academy in the year 1785, amount to 106. They have been all collected
into six octavo volumes entitled "Opuscula Torberni Bergman Physica et
Chemica"--with the exception of his notes on Scheffer, his Sciagraphia,
and his chapter on Physical Geography, which was translated into
French, and published in the Journal des Mines (vol. iii. No. 15, p.
55). His Sciagraphia, which is an attempt to arrange minerals according
to their composition, was translated into English by Dr. Withering.
His notes on Scheffer were interspersed in an edition of the "Chemiske
Föreläsningar" of that chemist, published in 1774, which he seems to
have employed as a text-book in his lectures: or, at all events, the
work was published for the use of the students of chemistry at Upsala.
There was a new edition of it published, after Bergman's death, in the
year 1796, to which are appended Bergman's Tables of Affinities.
The most important of Bergman's chemical papers were collected by
himself, and constitute the three first volumes of his Opuscula. The
three last volumes of that work were published after his death. The
fourth volume was published at Leipsic, in 1787, by Hebenstreit, and
contains the rest of his chemical papers. The fifth volume was given
to the world in 1788, by the same editor. It contains three chemical
papers, and the rest of it is made up with papers on natural history,
electricity, and other branches of physics, which Bergman had published
in the earlier part of his life. The same indefatigable editor
published the sixth volume in 1790. It contains three astronomical
papers, two chemical, and a long paper on the means of preventing any
injurious effects from lightning. This was an oration, delivered before
the Royal Academy of Sciences of Stockholm, in 1764, probably at the
time of his admission into the academy.
It would serve little purpose in the present state of chemical
knowledge, to give a minute analysis of Bergman's papers. To judge
of their value, it would be necessary to compare them, not with our
present chemical knowledge, but with the state of the science when
his papers were published. A very short general view of his labours
will be sufficient to convey an idea of the benefits which the science
derived from them.
1. His first paper, entitled "On the Aerial Acid," that is, _carbonic
acid_, was published in 1774. In it he gives the properties of this
substance in considerable detail, shows that it possesses acid
qualities, and that it is capable of combining with the bases, and
forming salts. What is very extraordinary, in giving an account of
carbonate of lime and carbonate of magnesia, he never mentions the name
of Dr. Black; though it is very unlikely that a controversy, which had
for years occupied the attention of chemists, should have been unknown
to him. Mr. Cavendish's name never once appears in the whole paper;
though that philosopher had preceded him by seven or eight years. He
informs us, that he had made known his opinions respecting the nature
of this substance, to various foreign correspondents, among others
to Dr. Priestley, as early as the year 1770, and that Dr. Priestley
had mentioned his views on the subject, in a paper inserted in the
Philosophical Transactions for 1772. Bergman found the specific gravity
of carbonic acid gas rather higher than 1·5, that of air being 1.
His result is not far from the truth. He obtained his gas, by mixing
calcareous spar with dilute sulphuric acid. He shows that this gas
has a sour taste, that it reddens the infusion of litmus, and that
it combines with bases. He gives figures of the apparatus which he
used. This apparatus demands attention. Though far inferior to the
contrivances of Priestley, it answered pretty well, enabling him to
collect the gas, and examine its properties.
It is unnecessary to enter into any further details respecting this
paper. Whoever will take the trouble to compare it with Cavendish's
paper on the same subject, will find that he had been anticipated by
that philosopher in a great many of his most important facts. Under
these circumstances, I consider as singular his not taking any notice
of Cavendish's previous labours.
2. His next paper, "On the Analyses of Mineral Waters," was first
published in 1778, being the subject of a thesis, supported by J.
P. Scharenberg. This dissertation, which is of great length, is
entitled to much praise. He lays therein the foundation of the mode of
analyzing waters, such as is followed at present. He points out the
use of different reagents, for detecting the presence of the various
constituents in mineral water, and then shows how the quantity of each
is to be determined. It would be doing great injustice to Bergman, to
compare his analyses with those of any modern experimenter. At that
time, the science was not in possession of any accurate analyses of
the neutral salts, which exist in mineral waters. Bergman undertook
these necessary analyses, without which, the determination of the
saline constituents of mineral waters was out of the question. His
determinations were not indeed accurate, but they were so much
better than those that preceded them, and Bergman's character as an
experimenter stood so high, that they were long referred to as a
standard by chemists. The first attempt to correct them was by Kirwan.
But Bergman's superior reputation as a chemist enabled his results
still to keep their ground, till his character for accuracy was finally
destroyed by the very accurate experiments which the discovery of
the atomic theory rendered it necessary to make. These, when once
they became generally known, were of course preferred, and Bergman's
analyses were laid aside.
It is a curious and humiliating fact, as it shows how much chemical
reputation depends upon situation, or accidental circumstances, that
Wenzel had, in 1766, in his book on _affinity_, published much more
accurate analyses of all these salts, than Bergman's--analyses indeed
which were almost perfectly correct, and which have scarcely been
surpassed, by the most careful ones of the present day. Yet these
admirable experiments scarcely drew the attention of chemists; while
the very inferior ones of Bergman were held up as models of perfection.
3. Bergman, not satisfied with pointing out the mode of analyzing
mineral waters, attempted to imitate them artificially by chemical
processes, and published two essays on the subject; in the first he
showed the processes by which cold mineral waters might be imitated,
and in the other, the mode of imitating hot mineral waters. The attempt
was valuable, and served to extend greatly the chemical knowledge of
mineral waters, and of the salts which they contain; but it was made
at too early a period of the analytical art, to approach perfection.
A similar remark applies to his analysis of sea-water. The water
examined was brought by Sparmann from a depth of eighty fathoms, near
the latitude of the Canaries: Bergman found in it only common salt,
muriate of magnesia, and sulphate of lime. His not having discovered
the presence of sulphate of magnesia is a sufficient proof of the
imperfection of his analytical methods; the other constituents exist
in such small quantity in sea-water that they might easily have been
overlooked, but the quantity of sulphate of magnesia in sea-water is
considerable.
4. I shall pass over the paper on oxalic acid, which constituted the
subject of a thesis, supported in 1776, by John Afzelius Arfvedson.
It is now known that oxalic acid was discovered by Scheele, not by
Bergman. It is impossible to say how many of the numerous facts
stated in this thesis were ascertained by Scheele, and how many
by Afzelius. For, as Afzelius was already a _magister docens_ in
chemistry, there can be little doubt that he would himself ascertain
the facts which were to constitute the foundation of his thesis. It
is indeed now known that Bergman himself intrusted all the details of
his experiments to his pupils. He was the contriver, while his pupils
executed his plans. That Scheele has nowhere laid claim to a discovery
of so much importance as that of oxalic acid, and that he allowed
Bergman peaceably to bear away the whole credit, constitutes one of
the most remarkable facts in the history of chemistry. Moreover, while
it reflects so much credit on Scheele for modesty and forbearance,
it seems to bear a little hard upon the character of Bergman. When
he published the essay in the first volume of his Opuscula, in 1779,
why did he not in a note inform the world that Scheele was the
true discoverer of this acid? Why did he allow the discovery to be
universally assigned to him, without ever mentioning the true state of
the case? All this appeared so contrary to the character of Bergman,
that I was disposed to doubt the truth of the statement, that Scheele
was the discoverer of oxalic acid. When I was at Fahlun, in the year
1812, I took an opportunity of putting the question to Assessor Gahn,
who had been the intimate friend of Scheele, and the pupil, and
afterwards the friend of Bergman. He assured me that Scheele really was
the discoverer of oxalic acid, and ascribed the omission of Bergman to
inadvertence. Assessor Gahn showed me a volume of Scheele's letters
to him, which he had bound up: they contained the history of all his
chemical labours. I have little doubt that an account of oxalic acid
would be found in these letters. If the son of Assessor Gahn, in whose
possession these letters must now be, would take the trouble to inspect
the volume in question, and to publish any notices respecting this acid
which they may contain, he would confer an important favour on every
person interested in the history of chemistry.
5. The dissertation on the manufacture of alum has been mentioned
before. Bergman shows himself well acquainted with the processes
followed, at least in Sweden, for making alum. He had no notion of
the true constitution of alum; nor was that to be expected, as the
discovery was thereby years later in being made. He thought that the
reason why alum leys did not crystallize well was, that they contained
an excess of acid, and that the addition of potash gave them the
property of crystallizing readily, merely by saturating that excess
of acid. Alum is a double salt, composed of three integrant particles
of sulphate of alumina, and one integrant particle of sulphate of
potash, or sulphate of ammonia. In some cases, the alum ore contains
all the requisite ingredients. This is the case with the ore at Tolfa,
in the neighbourhood of Rome. It seems, also, to be the case with
respect to some of the alum ores in Sweden; particularly at Hœnsœter
on Kinnekulle, in West Gothland, which I visited in 1812. If any
confidence can be put in the statements of the manager of those works,
no alkaline salt whatever is added; at least, I understood him to say
so when I put the question.
6. In his dissertation on tartar-emetic, he gives an interesting
historical account of this salt and its uses. His notions respecting
the antimonial preparations best fitted to form it, are not accurate:
nor, indeed, could they be expected to be so, till the nature and
properties of the different oxides of antimony were accurately
known. Antimony forms three _oxides_: now it is the protoxide alone
that is useful in medicine, and that enters into the composition
of tartar-emetic; the other two oxides are inert, or nearly so.
Bergman was aware that tartar-emetic is a double salt, and that its
constituents are tartaric acid, potash, and oxide of antimony; but it
was not possible, in 1773, when his dissertation was published, to have
determined the true constituents of this salt by analysis.
7. Bergman's paper on magnesia was also a thesis defended in 1775,
by Charles Norell, of West Gothland, who in all probability made the
experiments described in the essay. In the introduction we have a
history of the discovery of magnesia, and he mentions Dr. Black as the
person who first accurately made out its peculiar chemical characters,
and demonstrated that it differs from lime. This essay contains a
pretty full and accurate account of the salts of magnesia, considering
the state of chemistry at the time when it was published. There is no
attempt to analyze any of the magnesian salts; but, in his treatise on
the analysis of mineral waters, he had stated the quantity of magnesia
contained in one hundred parts of several of them.
8. His paper on the _shapes of crystals_, published in 1773, contains
the germ of the whole theory of crystallization afterwards developed by
M. Hauy. He shows how, from a very simple primary form of a mineral,
other shapes may proceed, which seem to have no connexion with, or
resemblance to the primary form. His view of the subject, so far as
it goes, is the very same afterwards adopted by Hauy: and, what is
very curious, Hauy and Bergman formed their theory from the very
same crystalline shape of calcareous spar--from which, by mechanical
divisions, the same rhombic nucleus was extracted by both. Nothing
prevented Bergman from anticipating Hauy but a sufficient quantity of
crystals to apply his theory to.[2]
[2] I shall mention afterwards that the real discoverer of this fact
was Assessor Gahn, of Fahlun.
9. In his paper on silica he gives us a history of the progress of
chemical knowledge respecting this substance. Its nature was first
accurately pointed out by Pott; though Glauber, and before him Van
Helmont, were acquainted with the _liquor silicus_, or the combination
of silica and potash, which is soluble in water. Bergman gives a
detailed account of its properties; but he does not suspect it to
possess acid properties. This great discovery, which has thrown a
new light upon mineral bodies, and shown them all to be chemical
combinations, was reserved for Mr. Smithson.
10. Bergman's experiments on the precious stones constitute the first
rudiments of the method of analyzing stony bodies. His processes are
very imperfect, and his apparatus but ill adapted to the purpose. We
need not be surprised, therefore, that the results of his analyses
are extremely wide of the truth. Yet, if we study his processes, we
shall find in them the rudiments of the very methods which we follow
at present. The superiority of the modern analyses over those of
Bergman must in a great measure be ascribed to the platinum vessels
which we now employ, and to the superior purity of the substances which
we use as reagents in our analyses. The methods, too, are simplified
and perfected. But we must not forget that this paper of Bergman's,
imperfect as it is, constitutes the commencement of the art, and that
fully as much genius and invention may be requisite to contrive the
first rude processes, how imperfect soever they may be, as are required
to bring these processes when once invented to a state of comparative
perfection. The great step in analyzing minerals is to render them
soluble in acids. Bergman first thought of the method for accomplishing
this which is still followed, namely, fusing them or heating them to
redness with an alkali or alkaline carbonate.
11. The paper on fulminating gold goes a great way to explain the
nature of that curious compound. He describes the properties of this
substance, and the effects of alkaline and acid bodies on it. He
shows that it cannot be formed without ammonia, and infers from his
experiments that it is a compound of oxide of gold and ammonia. He
explains the fulmination by the elastic fluid suddenly generated by the
decomposition of the ammonia.
12. The papers on platinum, carbonate of iron, nickel, arsenic, and
zinc, do not require many remarks. They add considerably to the
knowledge which chemists at that time possessed of these bodies; though
the modes of analysis are not such as would be approved of by a modern
chemist; nor were the results obtained possessed of much precision.
13. The Essay on the Analysis of Metallic Ores by the wet way, or by
solution, constitutes the first attempt to establish a regular method
of analyzing metallic ores. The processes are all imperfect, as might
be expected from the then existing state of analytical chemistry, and
the imperfect knowledge possessed, of the different metallic ores.
But this essay constituted a first beginning, for which the author is
entitled to great praise. The subject was taken up by Klaproth, and
speedily brought to a great degree of improvement by the labours of
modern chemists.
14. The experiments on the way in which minerals behave before the
blowpipe, which Bergman published, were made at Bergman's request
by Assessor Gahn, of Fahlun, who was then his pupil. They constitute
the first results obtained by that very ingenious and amiable man. He
afterwards continued the investigation, and added many improvements,
simplifying the reagents and the manner of using them. But he was too
indolent a man to commit the results of his investigations to writing.
Berzelius, however, had the good sense to see the importance of the
facts which Gahn had ascertained. He committed them to writing, and
published them for the use of mineralogists. They constitute the book
entitled "Berzelius on the Blowpipe," which has been translated into
English.
15. The object of the Essay on Metallic Precipitates is to determine
the quantity of phlogiston which each metal contains, deduced from
the quantity of one metal necessary to precipitate a given weight of
another. The experiments are obviously made with little accuracy:
indeed they are not susceptible of very great precision. Lavoisier
afterwards made use of the same method to determine the quantity of
oxygen in the different metallic oxides; but his results were not more
successful than those of Bergman.
16. Bergman's paper on iron is one of the most important in his whole
works, and contributed very materially to advance the knowledge of
the cause of the difference between iron and steel. He employed
his pupils to collect specimens of iron from the different Swedish
forges, and gave them directions how to select the proper pieces.
All these specimens, to the number of eighty-nine, he subjected to a
chemical examination, by dissolving them in dilute sulphuric acid. He
measured the volume of hydrogen gas, which he obtained by dissolving
a given weight of each, and noted the quantity and the nature of the
undissolved residue. The general result of the whole investigation
was that pure malleable iron yielded most hydrogen gas; steel less,
and cast-iron least of all. Pure malleable iron left the smallest
quantity of insoluble matter, steel a greater quantity, and cast-iron
the greatest of all. From these experiments he drew conclusions with
respect to the difference between iron, steel, and cast-iron. Nothing
more was necessary than to apply the antiphlogistic theory to these
experiments, (as was done soon after by the French chemists,) in
order to draw important conclusions respecting the nature of these
bodies. Iron is a simple body; steel is a compound of iron and carbon;
and cast-iron of iron and a still greater proportion of carbon. The
defective part of the experiments of Bergman in this important paper
is his method of determining the quantity of _manganese_ in iron. In
some specimens he makes the manganese amount to considerably more than
a third part of the weight of the whole. Now we know that a mixture of
two parts iron and one part manganese is brittle and useless. We are
sure, therefore, that no malleable iron whatever can contain any such
proportion of manganese. The fact is, that Bergman's mode of separating
manganese from iron was defective. What he considered as manganese was
chiefly, and might be in many cases altogether, oxide of iron. Many
years elapsed before a good process for separating iron from manganese
was discovered.
17. Bergman's experiments to ascertain the cause of the brittleness of
cold-short iron need not occupy much of our attention. He extracted
from it a white powder, by dissolving the cold-short iron in dilute
sulphuric acid. This white powder he succeeded in reducing to the state
of a white brittle metal, by fusing it with a flux and charcoal.
Klaproth soon after ascertained that this metal was a phosphuret of
iron, and that the white powder was a phosphate of iron: and Scheele,
with his usual sagacity, hit on a method of analyzing this phosphate,
and thus demonstrating its nature. Thus Bergman's experiments led to
the knowledge of the fact that cold-short iron owes its brittleness to
a quantity of phosphorus which it contains. It ought to be mentioned
that Meyer, of Stettin, ascertained the same fact, and made it known to
chemists at about the same time with Bergman.
18. The dissertation on the products of volcanoes, first published in
1777, is one of the most striking examples of the sagacity of Bergman
which we possess. He takes a view of all the substances certainly known
to have been thrown out of volcanoes, attempts to subject them to a
chemical analysis, and compares them with the basalt, and greenstone or
trap-rocks, the origin of which constituted at that time a keen matter
of dispute among geologists. He shows the identity between lavas and
basalt and greenstone, and therefore infers the identity of formation.
This is obviously the true mode of proceeding, and, had it been adopted
at an earlier period, many of those disputes respecting the nature of
trap-rocks, which occupied geologists for so long a period, would never
have been agitated; or, at least, would have been speedily decided. The
whole dissertation is filled with valuable matter, still well entitled
to the attention of geologists. His observations on _zeolites_, which
he considered as unconnected with volcanic products, were very natural
at the time when he wrote: though the subsequent experiments of Sir
James Hall, and Mr. Gregory Watt, and, above all, an accurate attention
to the scoriæ from different smelting-houses, have thrown a new light
on the subject, and have shown the way in which zeolitic crystals
might easily have been formed in melted lava, provided circumstances
were favourable. In fact, we find abundant cavities in real lava from
Vesuvius, filled with zeolitic crystals.
19. The last of the labours of Bergman which I shall notice here is
his Essay on Elective Attractions, which was originally published
in 1775, but was much augmented and improved in the third volume of
his Opuscula, published in 1783. An English translation of this last
edition of the Essay was made by Dr. Beddoes, and was long familiar to
the British chemical world. The object of this essay was to elucidate
and explain the nature of chemical affinity, and to account for all the
apparent anomalies that had been observed. He laid it down as a first
principle, that all bodies capable of combining chemically with each
other, have an attraction for each other, and that this attraction is
a definite and fixed force which may be represented by a number. Now
the bodies which have the property of uniting together are chiefly the
acids and the alkalies, or bases. Every acid has an attraction for each
of the alkalies or bases; but the force of this attraction differs in
each. Some bases have a strong attraction for acids, and others a weak;
but the attractive force of each may be expressed by numbers.
Now, suppose that an acid _a_ is united with a base _m_ with a certain
force, if we mix the compound _a m_ with a certain quantity of the
base _n_, which has a stronger attraction for _a_ than _m_ has, the
consequence will be, that _a_ will leave _m_ and unite with _n_;--_n_
having a stronger attraction for _a_ than _m_ has, will disengage it
and take its place. In consequence of this property, which Bergman
considered as the foundation of the whole of the science, the
strength of affinity of one body for another is determined by these
decompositions and combinations. If _n_ has a stronger affinity for
_a_ than _m_ has, then if we mix together _a_, _m_, and _n_ in the
requisite proportions, _a_ and _n_ will unite together, leaving _m_
uncombined: or if we mix _n_ with the compound _a m_, _m_ will be
disengaged. Tables, therefore, may be drawn up, exhibiting the strength
of these affinities. At the top of a column is put the name of an
_acid_ or a _base_, and below it are put the names of all the _bases_
or _acids_ in the order of their affinity. The following little table
will exhibit a specimen of these columns:
_Sulphuric Acid._
Barytes
Strontian
Potash
Soda
Lime
Magnesia.
Here sulphuric acid is the substance placed at the head of the column,
and under it are the names of the bases capable of uniting with it in
the order of their affinity. Barytes, which is highest up, has the
strongest affinity, and magnesia, which is lowest down, has the weakest
affinity. If sulphuric acid and magnesia were combined together, all
the bases whose names occur in the table above magnesia would be able
to separate the sulphuric acid from it. Potash would be disengaged from
sulphuric acid by barytes and strontian, but not by soda, lime, and
magnesia.
Such tables then exhibited to the eye the strength of affinity of all
the different bodies that are capable of uniting with one and the same
substance, and the order in which decompositions are effected. Bergman
drew up tables of affinity according to these views in fifty-nine
columns. Each column contained the name of a particular substance,
and under it was arranged all the bodies capable of uniting with it,
each in the order of its affinity. Now bodies may be made to unite,
either by mixing them together, and then exposing them to heat, or
by dissolving them in water and mixing the respective solutions
together. The first of these ways is usually called the _dry way_,
the second the _moist way_. The order of decompositions often varies
with the mode employed. On this account, Bergman divided each of his
fifty-nine columns into two. In the first, he exhibited the order of
decompositions in the moist way, in the second in the dry. He explained
also the cases of double decomposition, by means of these unvarying
forces acting together or opposing each other--and gave sixty-four
cases of such double decompositions.
These views of Bergman's were immediately acceded to by the chemical
world, and continued to regulate their processes till Berthollet
published his Chemical Statics in 1802. He there called in question the
whole doctrine of Bergman, and endeavoured to establish one of the very
opposite kind. I shall have occasion to return to the subject when I
come to give an account of the services which Berthollet conferred upon
chemistry.
I have already observed, that we are under obligations to Bergman, not
merely for the improvements which he himself introduced into chemistry,
but for the pupils whom he educated as chemists, and the discoveries
which were made by those persons, whose exertions he stimulated and
encouraged. Among those individuals, whose chemical discoveries were
chiefly made known to the world by his means, was Scheele, certainly
one of the most extraordinary men, and most sagacious and industrious
chemists that ever existed.
Charles William Scheele was born on the 19th of December, 1742, at
Stralsund, the capital of Swedish Pomerania, where his father was a
tradesman. He received the first part of his education at a private
academy in Stralsund, and was afterwards removed to a public school.
At a very early period he expressed a strong desire to study pharmacy,
and obtained his father's consent to make choice of this profession.
He was accordingly bound an apprentice for six years to Mr. Bouch, an
apothecary in Gotheborg, and after his time was out, he remained with
him still, two years longer.
It was here that he laid the groundwork of all his future celebrity,
as we are informed by Mr. Grunberg, who was his fellow-apprentice,
and afterwards settled as an apothecary in Stralsund. He was at that
time very reserved and serious, but uncommonly diligent. He attended
minutely to all the processes, reflected upon them while alone, and
studied the writings of Neumann, Lemery, Kunkel, and Stahl, with
indefatigable industry. He likewise exercised himself a good deal
in drawing and painting, and acquired some proficiency in these
accomplishments without a master. Kunkel's Laboratorium was his
favourite book, and he was in the habit of repeating experiments out of
it secretly during the night-time. On one occasion, as he was employed
in making pyrophorus, his fellow-apprentice was malicious enough to
put a quantity of fulminating powder into the mixture. The consequence
was a violent explosion, which, as it took place in the night, threw
the whole family into confusion, and brought a very severe rebuke
upon our young chemist. But this did not put a stop to his industry,
which he pursued so constantly and judiciously, that, by the time his
apprenticeship was ended, there were very few chemists indeed who
excelled him in knowledge and practical skill. His fellow-apprentice,
Mr. Grunberg, wrote to him in 1774, requesting to know by what means he
had become such a proficient in chemistry, and received the following
answer: "I look upon you, my dear friend, as my first instructor,
and as the author of all I know on the subject, in consequence of
your advising me to read Neumann's Chemistry. The perusal of this
book first gave me a taste for experimenting, myself; and I very well
remember, that upon mixing some oil of cloves and smoking spirit of
nitre together, they took fire. However, I kept this matter secret.
I have also before my eyes the unfortunate experiment which I made
with pyrophorus. Such accidents only served to increase my passion for
making experiments."
In 1765 Scheele went to Malmo, to the house of an apothecary, called
Mr. Kalstrom. After spending two years in that place, he went to
Stockholm, to superintend the apothecary's shop of Mr. Scharenberg. In
1773 he exchanged this situation for another at Upsala, in the house of
Mr. Loock. It was here that he accidentally formed an acquaintance with
Assessor Gahn, of Fahlun, who was at that time a student at Upsala, and
a zealous chemist. Mr. Gahn happening to be one day in the shop of Mr.
Loock, that gentleman mentioned to him a circumstance which had lately
occurred to him, and of which he was anxious to obtain an explanation.
If a quantity of saltpetre be put into a crucible and raised to such a
temperature as shall not merely melt it, but occasion an agitation in
it like boiling, and if, after a certain time, the crucible be taken
out of the fire and allowed to cool, the saltpetre still continues
neutral; but its properties are altered: for, if distilled vinegar be
poured upon it, red fumes are given out, while vinegar produces no
effect upon the saltpetre before it has been thus heated. Mr. Loock
wished from Gahn an explanation of the cause of this phenomenon: Gahn
was unable to explain it; but promised to put the question to Professor
Bergman. He did so accordingly, but Bergman was as unable to find an
explanation as himself. On returning a few days after to Mr. Loock's
shop, Gahn was informed that there was a young man in the shop who had
given an explanation of the phenomenon. This young man was Scheele, who
had informed Mr. Loock that there were two species of acids confounded
under the name of _spirit of nitre_; what we at present call _nitric_
and _hyponitrous_ acids. Nitric acid has a stronger affinity for potash
than vinegar has; but hyponitrous acid has a weaker. The heat of the
fire changes the _nitric_ acid of the saltpetre to _hyponitrous_: hence
the phenomenon.
Gahn was delighted with the information, and immediately formed an
acquaintance with Scheele, which soon ripened into friendship. When he
informed Bergman of Scheele's explanation, the professor was equally
delighted, and expressed an eager desire to be made acquainted with
Scheele; but when Gahn mentioned the circumstance to Scheele, and
offered to introduce him to Bergman, our young chemist rejected the
proposal with strong feelings of dislike.
It seems, that while Scheele was in Stockholm, he had made experiments
on cream of tartar, and had succeeded in separating from it tartaric
acid, in a state of purity. He had also determined a number of the
properties of tartaric acid, and examined several of the tartrates. He
drew up an account of these results, and sent it to Bergman. Bergman,
seeing a paper subscribed by the name of a person who was unknown to
him, laid it aside without looking at it, and forgot it altogether.
Scheele was very much provoked at this contemptuous and unmerited
treatment. He drew up another account of his experiments and gave it to
Retzius, who sent it to the Stockholm Academy of Sciences (with some
additions of his own), in whose Memoirs it was published in the year
1770.[3] It cost Assessor Gahn considerable trouble to satisfy Scheele
that Bergman's conduct was merely the result of inadvertence, and that
he had no intention whatever of treating him either with contempt or
neglect. After much entreaty, he prevailed upon Scheele to allow him
to introduce him to the professor of chemistry. The introduction took
place accordingly, and ever after Bergman and Scheele continued steady
friends--Bergman facilitating the researches of Scheele by every means
in his power.
[3] Konig. Vetensk. Acad. Handl. 1770, p. 207.
So high did the character of Scheele speedily rise in Upsala, that when
the Duke of Sudermania visited the university soon after, in company
with Prince Henry of Prussia, Scheele was appointed by the university
to exhibit some chemical processes before him. He fulfilled his charge,
and performed in different furnaces several curious and striking
experiments. Prince Henry asked him various questions, and expressed
satisfaction at the answers given. He was particularly pleased
when informed that he was a native of Stralsund. These two princes
afterwards stated to the professors that they would take it as a favour
if Scheele could have free access to the laboratory of the university
whenever he wished to make experiments.
In the year 1775, on the death of Mr. Popler, apothecary at Köping (a
small place on the north side of the lake Mæler), he was appointed by
the Medical College _provisor_ of the apothecary's shop. In Sweden all
the apothecaries are under the control of the Medical College, and no
one can open a shop without undergoing an examination and receiving
licence from that learned body. In the course of the examinations
which he was obliged to undergo, Scheele gave great proofs of his
abilities, and obtained the appointment. In 1777 the widow sold him
the shop and business, according to a written agreement made between
them; but they still continued housekeeping at their joint expense. He
had already distinguished himself by his discovery of fluoric acid,
and by his admirable paper on manganese. It is said, too, that it was
he who made the experiments on carbonic acid gas, which constitute the
substance of Bergman's paper on the subject, and which confirmed and
established Bergman's idea that it was an acid. At Köping he continued
his researches with unremitting perseverance, and made more discoveries
than all the chemists of his time united together. It was here that he
made the experiments on air and fire, which constitute the materials of
his celebrated work on these subjects. The theory which he formed was
indeed erroneous; but the numerous discoveries which the book contains
must always excite the admiration of every chemist. His discovery of
oxygen gas had been anticipated by Priestley; but his analysis of
atmospheric air was new and satisfactory--was peculiarly his own. The
processes by means of which he procured oxygen gas were also new,
simple, and easy, and are still followed by chemists in general. During
his residence at Köping he published a great number of chemical papers,
and every one of them contained a discovery. The whole of his time was
devoted to chemical investigations. Every action of his life had a
tendency to forward the advancement of his favourite science; all his
thoughts were turned to the same object; all his letters were devoted
to chemical observations and chemical discussions. Crell's Annals was
at that time the chief periodical work on chemistry in Germany. He got
the numbers regularly as they were published, and was one of Crell's
most constant and most valuable correspondents. Every one of his
letters published in that work either contains some new chemical fact,
or exposes the errors and mistakes of some one or other of Crell's
numerous correspondents.
Scheele's outward appearance was by no means prepossessing. He seldom
joined in the usual conversations and amusements of society, having
neither leisure nor inclination for them. What little time he had to
spare from the hurry of his profession was always employed in making
experiments. It was only when he received visits from his friends,
with whom he could converse on his favourite science, that he indulged
himself in a little relaxation. For such intimate friends he had
a sincere affection. This regard was extended to all the zealous
cultivators of chemistry in every part of the world, whether personally
known to him or not. He kept up a correspondence with several; though
this correspondence was much limited by his ignorance of all languages
except German; for at least he could not write fluently in any other
language. His chemical papers were always written in German, and
translated into Swedish, before they were inserted in the Memoirs of
the Stockholm Academy, where most of them appeared.
He was kind and affable to all. Before he adopted an opinion in
science, he reflected maturely on it; but, after he had once embraced
it, his opinions were not easily shaken. However, he did not hesitate
to give up an opinion as soon as it had been proved to be erroneous.
Thus, he entirely renounced the notion which he once entertained that
_silica_ is a compound of _water_ and _fluoric acid_; because it was
demonstrated, by Meyer and others, that this _silica_ was derived
from the glass vessels in which the fluoric acid was prepared; that
these glass vessels were speedily corroded into holes; and that, if
fluoric acid was prepared in metallic vessels, and not allowed to come
in contact with glass or any substance containing silica, it might be
mixed with water without any deposition of silica whatever.
It appears also by a letter of his, published in Crell's Annals, that
he was satisfied of the accuracy of Mr. Cavendish's experiments,
showing that water was a compound of oxygen and hydrogen gases, and
of Lavoisier's repetition of them. He attempted to reconcile this
fact with his own notion, that heat is a compound of oxygen and
hydrogen. But his arguments on that subject, though ingenious, are not
satisfactory; and there is little doubt that if he had lived somewhat
longer, and had been able to repeat his own experiments, and compare
them with those of Cavendish and Lavoisier, he would have given up
his own theory and adopted that of Lavoisier, or, at any rate, the
explanation of Cavendish, which, being more conformable to his own
preconceived notions, might have been embraced by him in preference.
It is said by Dr. Crell that Scheele was invited over to England, with
an offer of an easy and advantageous situation; but that his love of
quiet and retirement, and his partiality for Sweden, where he had
spent the greatest part of his life, threw difficulties in the way
of these overtures, and that a change in the English ministry put a
stop to them for the time. The invitation, Crell says, was renewed
in 1786, with the offer of a salary of 300_l._ a-year; but Scheele's
death put a final stop to it. I have very great doubts about the truth
of this statement; and, many years ago, during the lifetime of Sir
Joseph Banks, Mr. Cavendish, and Mr. Kirwan, I made inquiry about the
circumstance; but none of the chemists in Great Britain, who were at
that time numerous and highly respectable, had ever heard of any such
negotiation. I am utterly at a loss to conceive what one individual
in any of the ministries of George III. was either acquainted with
the science of chemistry, or at all interested in its progress. They
were all so intent upon accomplishing their own objects, or those of
their sovereign, that they had neither time nor inclination to think
of science, and certainly no money to devote to any of its votaries.
What minister in Great Britain ever attempted to cherish the sciences,
or to reward those who cultivate them with success? If we except Mr.
Montague, who procured the place of master of the Mint for Sir Isaac
Newton, I know of no one. While in every other nation in Europe science
is directly promoted, and considerable sums are appropriated for its
cultivation, and for the support of a certain number of individuals
who have shown themselves capable of extending its boundaries, not a
single farthing has been devoted to any such purpose in Great Britain.
Science has been left entirely to itself; and whatever has been done
by way of promoting it has been performed by the unaided exertions of
private individuals. George III. himself was a patron of literature
and an encourager of _botany_. He might have been disposed to reward
the unrivalled eminence which Scheele had attained; but this he could
only have done by bestowing on him a pension out of his privy purse.
No situation which Scheele could fill was at his disposal. The
universities and the church were both shut against a Lutheran; and no
pharmaceutical places exist in this country to which Scheele could have
been appointed. If any such project ever existed, it must have been an
idea which struck some man of science that such a proposal to a man
of Scheele's eminence would redound to the credit of the country. But
that such a project should have been broached by a British ministry, or
by any man of great political influence, is an opinion that no person
would adopt who has paid any attention to the history of Great Britain
since the Revolution to the present time.
Scheele fell at last a sacrifice to his ardent love for his science. He
was unable to abstain from experimenting, and many of his experiments
were unavoidably made in his shop, where he was exposed during winter,
in the ungenial climate of Sweden, to cold draughts of air. He caught
rheumatism in consequence, and the disease was aggravated by his ardour
and perseverance in his pursuits. When he purchased the apothecary's
shop in which his business was carried on, he had formed the resolution
of marrying the widow of his predecessor, and he had only delayed
it from the honourable principle of acquiring, in the first place,
sufficient property to render such an alliance desirable on her part.
At length, in the month of March, 1786, he declared his intention of
marrying her; but his disease at this time increased very fast, and
his hopes of recovery daily diminished. He was sensible of this; but
nevertheless he performed his promise, and married her on the 19th of
May, at a time when he lay on his deathbed. On the 21st, he left her by
his will the disposal of the whole of his property; and, the same day
on which he so tenderly provided for her, he died.
I shall now endeavour to give the reader an idea of the principal
chemical discoveries for which we are indebted to Scheele: his papers,
with the exception of his book on _air and fire_, which was published
separately by Bergman, are all to be found either in the Memoirs of
the Stockholm Academy of Science, or in Crell's Journal; they were
collected, and a Latin translation of them, made by Godfrey Henry
Schaefer, published at Leipsic, in 1788, by Henstreit, the editor of
the three last volumes of Bergman's Opuscula. A French translation of
them was made in consequence of the exertions of M. Morveau; and an
English translation of them, in 1786, by means of Dr. Beddoes, when he
was a student in Edinburgh. There are also several German translations,
but I have never had an opportunity of seeing them.
1. Scheele's first paper was published by Retzius, in 1770; it gives a
method of obtaining pure tartaric acid: the process was to decompose
cream of tartar by means of chalk. One half of the tartaric acid unites
to the lime, and falls down in the state of a white insoluble powder,
being _tartrate of lime_. The cream of tartar, thus deprived of half
its acid, is converted into the neutral salt formerly distinguished
by the name of _soluble tartar_, from its great solubility in water:
it dissolves, and may be obtained in crystals, by the usual method of
crystallizing salts. The tartrate of lime is washed with water, and
then mixed with a quantity of dilute sulphuric acid, just capable of
saturating the lime contained in the tartrate of lime; the mixture
is digested for some time; the sulphuric acid displaces the tartaric
acid, and combines with the lime; and, as the sulphate of lime is but
very little soluble in water, the greatest part of it precipitates,
and the clear liquor is drawn off: it consists of tartaric acid,
held in solution by water, but not quite free from sulphate of lime.
By repeated concentrations, all the sulphate of lime falls down,
and at last the tartaric acid itself is obtained in large crystals.
This process is still followed by the manufacturers of this country;
for tartaric acid is used to a very considerable extent by the
calico-printers, in various processes; for example, it is applied,
thickened with gum, to different parts of cloth dyed Turkey red; the
cloth is then passed through water containing the requisite quantity of
chloride of lime: the tartaric acid, uniting with the lime, sets the
chlorine at liberty, which immediately destroys the red colour wherever
the tartaric acid has been applied, but leaves all the other parts of
the cloth unchanged.
2. The paper on _fluoric acid_ appeared in the Memoirs of the Stockholm
Academy, for 1771, when Scheele was in Scharenberg's apothecary's
shop in Stockholm, where, doubtless, the experiments were made. Three
years before, Margraaf had attempted an analysis of fluor spar, but
had discovered nothing. Scheele demonstrated that it is a compound of
lime and a peculiar acid, to which he gave the name of _fluoric_ acid.
This acid he obtained in solution in water; it was separated from
the fluor spar by sulphuric, muriatic, nitric, and phosphoric acids.
When the fluoric acid came in contact with water, a white crust was
formed, which proved, on examination, to be silica. Scheele at first
thought that this silica was a compound of fluoric acid and water; but
it was afterwards proved by Weigleb and by Meyer, that this notion is
inaccurate, and that the silica was corroded from the retort into which
the fluor spar and sulphuric acid were put. Bergman, who had adopted
Scheele's theory of the nature of silica, was so satisfied by these
experiments, that he gave it up, as Scheele himself did soon after.
Scheele did not obtain fluoric acid in a state of purity, put only
_fluosilicic acid_; nor were chemists acquainted with the properties
of fluoric acid till Gay-Lussac and Thenard published their Recherches
Physico-chimiques, in 1811.
3. Scheele's experiments on _manganese_ were undertaken at the request
of Bergman, and occupied him three years; they were published in the
Memoirs of the Stockholm Academy, for 1774, and constitute the most
memorable and important of all his essays, since they contain the
discovery of two new bodies, which have since acted so conspicuous a
part, both in promoting the progress of the science, and in improving
the manufactures of Europe. These two substances are _chlorine_ and
_barytes_, the first account of both of which occur in this paper.
The ore of manganese employed in these experiments was the _black
oxide_, or _deutoxide_, of manganese, as it is now called. Scheele's
method of proceeding was to try the effect of all the different
reagents on it. It dissolved in sulphurous and nitrous acids, and the
solution was colourless. Dilute sulphuric acid did not act upon it,
nor nitric acid; but concentrated sulphuric acid dissolved it by the
assistance of heat. The solution of sulphate of manganese in water was
colourless and crystallized in very oblique rhomboidal prisms, having
a bitter taste. Muriatic acid effervesced with it, when assisted by
heat, and the elastic fluid that passed off had a yellowish colour, and
the smell of aqua regia. He collected quantities of this elastic fluid
(_chlorine_) in bladders, and determined some of its most remarkable
properties: it destroyed colours, and tinged the bladder yellow,
as nitric acid does. This elastic fluid, in Scheele's opinion, was
muriatic acid deprived of phlogiston. By phlogiston Scheele meant, in
this place, hydrogen gas. He considered muriatic acid as a compound
of chlorine and hydrogen. Now this is the very theory that was
established by Davy in consequence of his own experiments and those of
Gay-Lussac and Thenard. Scheele's mode of collecting chlorine gas in a
bladder, did not enable him to determine its characters with so much
precision as was afterwards done. But his accuracy was so great, that
every thing which he stated respecting it was correct so far as it went.
Most of the specimens of manganese ore which Scheele examined,
contained more or less barytes, as has since been determined, in
combination with the oxide. He separated this barytes, and determined
its peculiar properties. It dissolved in nitric and muriatic acids,
and formed salts capable of crystallizing, and permanent in the air.
Neither potash, soda, nor lime, nor any _base_ whatever, was capable of
precipitating it from these acids. But the alkaline carbonates threw it
down in the state of a white powder, which dissolved with effervescence
in acids. Sulphuric acid and all the sulphates threw it down in the
state of a white powder, which was insoluble in water and in acids.
This sulphate cannot be decomposed by any acid or base whatever. The
only practicable mode of proceeding is to convert the sulphuric acid
into sulphur, by heating the salt with charcoal powder, along with a
sufficient quantity of potash, to bring the whole into fusion. The
fused mass, edulcorated, is soluble in nitric or muriatic acid, and
thus may be freed from charcoal, and the barytes obtained in a state
of purity. Scheele detected barytes, also, in the potash made from
trees or other smaller vegetables; but at that time he was unacquainted
with _sulphate of barytes_, which is so common in various parts of the
earth, especially in lead-mines.
To point out all the new facts contained in this admirable essay,
it would be necessary to transcribe the whole of it. He shows the
remarkable analogy between manganese and metallic oxides. Bergman, in
an appendix affixed to Scheele's paper, states his reasons for being
satisfied that it is really a metallic oxide. Some years afterwards,
Assessor Gahn succeeded in reducing it to the metallic state, and thus
dissipating all remaining doubts on the subject.
4. In 1775 he gave a new method of obtaining benzoic acid from benzoin.
His method was, to digest the benzoin with pounded chalk and water,
till the whole of the acid had combined with lime, and dissolved in the
water. It is requisite to take care to prevent the benzoin from running
into clots. The liquid thus containing benzoate of lime in solution is
filtered, and muriatic acid added in sufficient quantity to saturate
the lime. The benzoic acid is separated in white flocks, which may be
easily collected and washed. This method, though sufficiently easy, is
not followed by practical chemists, at least in this country. The acid
when procured by precipitation is not so beautiful as what is procured
by sublimation; nor is the process so cheap or so rapid. For these
reasons, Scheele's process has not come into general use.
5. During the same year, 1775, his essay on arsenic and its acid was
also published in the Memoirs of the Stockholm Academy. In this essay
he shows various processes, by means of which white arsenic may be
converted into an acid, having a very sour taste, and very soluble in
water. This is the acid to which the name of _arsenic acid_ has been
since given. Scheele describes the properties of this acid, and the
salts which it forms, with the different bases. He examines, also, the
action of white arsenic upon different bodies, and throws light upon
the arsenical salt of Macquer.
6. The object of the little paper on silica, clay, and alum, published
in the Memoirs of the Stockholm Academy, for 1776, is to prove that
alumina and silica are two perfectly distinct bodies, possessed
of different properties. This he does with his usual felicity of
experiment. He shows, also, that alumina and lime are capable of
combining together.
7. The same year, and in the same volume of the Stockholm Memoirs, he
published his experiments on a urinary calculus. The calculus upon
which his experiments were made, happened to be composed of _uric
acid_. He determined the properties of this new acid, particularly
the characteristic one of dissolving in nitric acid, and leaving a
beautiful pink sediment when the solution is gently evaporated to
dryness.
8. In 1778 appeared his experiments on molybdena. What is now called
_molybdena_ is a soft foliated mineral, having the metallic lustre,
and composed of two atoms sulphur united to one atom of metallic
molybdenum. It was known before, from the experiments of Quest, that
this substance contains sulphur. Scheele extracted from it a white
powder, which he showed to possess acid properties, though it was
insoluble in water. He examined the characters of this acid, called
molybdic acid, and the nature of the salts which it is capable of
forming by uniting with bases.
9. In the year 1777 was published the Experiments of Scheele on Air
and Fire, with an introduction, by way of preface, from Bergman, who
seems to have superintended the publication. This work is undoubtedly
the most extraordinary production that Scheele has left us; and is
really wonderful, if we consider the circumstances under which it was
produced. Scheele ascertained that common air is a mixture of two
distinct elastic fluids, one of which alone is capable of supporting
combustion, and which, therefore, he calls _empyreal air_; the
other, being neither capable of maintaining combustion, nor of being
breathed, he called _foul air_. These are the _oxygen_ and _azote_
of modern chemists. Oxygen he showed to be heavier than common air;
bodies burnt in it with much greater splendour than in common air.
Azote he found lighter than common air; bodies would not burn in it at
all. He showed that metallic _calces_, or metallic _oxides_, as they
are now called, contain oxygen as a constituent, and that when they
are reduced to the metallic state, oxygen gas is disengaged. In his
experiments on fulminating gold he shows, that during the fulmination
a quantity of azotic gas is disengaged; and he deduces from a great
many curious facts, which are stated at length, that ammonia is a
compound of _azote_ and _hydrogen_. His apparatus was not nice enough
to enable him to determine the proportions of the various ingredients
of the bodies which he analyzed: accordingly that is seldom attempted;
and when it is, as was the case with common air, the results are very
unsatisfactory. He deduces from his experiments, that the volume of
oxygen gas, in common air, is between a third and a fourth: we now know
that it is exactly a fifth.
In this book, also, we have the first account of sulphuretted
hydrogen gas, and of its properties. He gives it the name of stinking
sulphureous air.
The observations and new views respecting heat and light in this
work are so numerous, that I am obliged to omit them: nor do I think
it necessary to advert to his theory, which, when his book was
published, was exceedingly plausible, and undoubtedly constituted
a great step towards the improvements which soon after followed.
His own experiments, had he attended a little more closely to the
_weights_, and the alterations of them, would have been sufficient
to have overturned the whole doctrine of phlogiston. Upon the whole
it may be said, with confidence, that there is no chemical book in
existence which contains a greater number of new and important facts
than this work of Scheele, at the time it was published. Yet most of
his discoveries were made, also, by others. Priestley and Lavoisier,
from the superiority of their situations, and their greater means of
making their labours speedily known to the public, deprived him of
much of that reputation to which, in common circumstances, he would
have been entitled. Priestley has been blamed for the rapidity of his
publications, and the crude manner in which he ushered his discoveries
to the world. But had he kept them by him till he had brought them to
a sufficient degree of maturity, it is obvious that he would have been
anticipated in the most important of them by Scheele.
10. In the Memoirs of the Stockholm Academy, for 1779, there is a
short but curious paper of Scheele, giving an account of some results
which he had obtained. If a plate of iron be moistened by a solution
of common salt, or of sulphate of soda, and left for some weeks in a
moist cellar, an efflorescence of carbonate of soda covers the surface
of the plate. The same decomposition of common salt and evolution of
soda takes place when unslacked quicklime is moistened with a solution
of common salt, and left in a similar situation. These experiments led
afterwards to various methods of decomposing common salt, and obtaining
from it carbonate of soda. The phenomena themselves are still wrapped
up in considerable obscurity. Berthollet attempted an explanation
afterwards in his Chemical Statics; but founded on principles not
easily admissible.
11. During the same year, his experiments on _plumbago_ were published.
This substance had been long employed for making black-lead pencils;
but nothing was known concerning its nature. Scheele, with his usual
perseverance, tried the effect of all the different reagents, and
showed that it consisted chiefly of _carbon_, but was mixed with a
certain quantity of iron. It was concluded from these experiments,
that plumbago is a carburet of iron. But the quantity of iron differs
so enormously in different specimens, that this opinion cannot be
admitted. Sometimes the iron amounts only to one-half per cent., and
sometimes to thirty per cent. Plumbago, then, is carbon mixed with a
variable proportion of iron, or carburet of iron.
12. In 1780 Scheele published his experiments on milk, and showed that
sour milk contains a peculiar acid, to which the name of _lactic_ acid
has been given.
He found that when sugar of milk is dissolved in nitric acid, and the
solution allowed to cool, small crystalline grains were deposited.
These grains have an acid taste, and combine with bases: they have
peculiar properties, and therefore constitute a particular acid, to
which the name of _saclactic_ was given. It is formed, also, when
gum is dissolved in nitric acid; on this account it has been called,
_mucic_ acid.
13. In 1781 his experiments on a heavy mineral called by the Swedes
_tungsten_, were published. This substance had been much noticed on
account of its great weight; but nothing was known respecting its
nature. Scheele, with his usual skill and perseverance, succeeded in
proving that it was a compound of lime and a peculiar acid, to which
the name of _tungstic acid_ was given. Tungsten was, therefore, a
tungstate of lime. Bergman, from its great weight, suspected that
tungstic acid was in reality the oxide of a metal, and this conjecture
was afterwards confirmed by the Elhuyarts, who extracted the same acid
from wolfram, and succeeded in reducing it to the metallic state.
14. In 1782 and 1783 appeared his experiments on _Prussian blue_, in
order to discover the nature of the colouring matter. These experiments
were exceedingly numerous, and display uncommon ingenuity and sagacity.
He succeeded in demonstrating that _prussic acid_, the name at that
time given to the colouring principle, was a compound of _carbon_ and
_azote_. He pointed out a process for obtaining prussic acid in a
separate state, and determined its properties. This paper threw at once
a ray of light on one of the obscurest parts of chemistry. If he did
not succeed in elucidating this difficult department completely, the
fault must not be ascribed to him, but to the state of chemistry when
his experiments were made; in fact, it would have been impossible to
have gone further, till the nature of the different elastic fluids at
that time under investigation had been thoroughly established. Perhaps
in 1783 there was scarcely any other individual who could have carried
this very difficult investigation so far as it was carried by Scheele.
15. In 1783 appeared his observations on the _sweet principle of oils_.
He observed, that when olive oil and litharge are combined together,
a sweet substance separates from the oil and floats on the surface.
This substance, when treated with nitric acid, yields _oxalic acid_. It
was therefore closely connected with sugar in its nature. He obtained
the same sweet matter from linseed oil, oil of almonds, of rape-seed,
from hogs' lard, and from butter. He therefore concluded that it was a
principle contained in all the expressed or fixed oils.
16. In 1784 he pointed out a method by which _citric acid_ may be
obtained in a state of purity from lemon-juice. He likewise determined
its characters, and showed that it was entitled to rank as a peculiar
acid.
It was during the same year that he observed a white earthy matter,
which may be obtained by washing rhubarb, in fine powder, with a
sufficient quantity of water. This earthy matter he decomposed, and
ascertained that it was a neutral salt, composed of oxalic acid,
combined with lime. In a subsequent paper he showed, that the same
oxalate of lime exists in a great number of roots of various plants.
17. In 1786 he showed that apples contain a peculiar acid, the
properties of which he determined, and to which the name of _malic
acid_ has been given. In the same paper he examined all the common acid
fruits of this country--gooseberries, currants, cherries, bilberries,
&c., and determined the peculiar acids which they contain. Some owe
their acidity to malic acid, some to citric acid, and some to tartaric
acid; and not a few hold two, or even three, of these acids at the same
time.
The same year he showed that the syderum of Bergman was phosphuret of
iron, and the _acidum perlatum_ of Proust _biphosphate of soda_.
The only other publication of Scheele, during 1785, was a short
notice respecting a new mode of preparing _magnesia alba_. If
sulphate of magnesia and common salt, both in solution, be mixed in
the requisite proportions, a double decomposition takes place, and
there will be formed sulphate of soda and muriate of magnesia. The
greatest part of the former salt may be obtained out of the mixed ley
by crystallization, and then the magnesia alba may be thrown down,
from the muriate of magnesia, by means of an alkaline carbonate. The
advantage of this new process is, the procuring of a considerable
quantity of sulphate of soda in exchange for common salt, which is a
much cheaper substance.
18. The last paper which Scheele published appeared in the Memoirs
of the Stockholm Academy, for 1786: in it he gave an account of the
characters of gallic acid, and the method of obtaining that acid from
nutgalls.
Such is an imperfect sketch of the principal discoveries of Scheele.
I have left out of view his controversial papers, which have now lost
their interest; and a few others of minor importance, that this notice
might not be extended beyond its due length. It will be seen that
Scheele extended greatly the number of acids; indeed, he more than
doubled the number of these bodies known when he began his chemical
labours. The following acids were discovered by him; or, at least, it
was he that first accurately pointed out their characters:
Fluoric acid
Molybdic acid
Tungstic acid
Arsenic acid
Lactic acid
Gallic acid
Tartaric acid
Oxalic acid
Citric acid
Malic acid
Saclactic
Chlorine.
To him, also, we owe the first knowledge of barytes, and of the
characters of manganese. He determined the nature of the constituents
of ammonia and prussic acid: he first determined the compound nature of
common air, and the properties of the two elastic fluids of which it is
composed. What other chemist, either a contemporary or predecessor of
Scheele, can be brought in competition with him as a discoverer? And
all was performed under the most unpropitious circumstances, and during
the continuance of a very short life, for he died in the 44th year of
his age.