It was the fortune of this eminent philosopher, in the course of a long,
uncompromising advocacy of his own views of truth, to become prominently
engaged in controversy on those two great sources of discord, religion
and politics. He was grossly maltreated by those who disapproved of his
doctrines; and, as the natural consequence, he was regarded with warm,
not to say immoderate, admiration by his friends. His opinions, however,
were the result of patient inquiry, instituted and pursued, as we
believe, with a sincere desire to arrive at truth; and therefore he is
entitled to be treated with respect, even by those who think his
opinions of pernicious tendency. A good life of such a man can hardly
satisfy both friends and enemies. It is, however, as a man of science,
not as a party disputant, that Priestley is entitled to a place here;
and we shall therefore hold ourselves excused from entering at length
into his political or theological controversies.
JOSEPH PRIESTLEY was born at Fieldhead, near Leeds, March 13, 1733, O.S.
His father was of middle rank, engaged in the woollen manufactures of
the neighbourhood. His mother died while he was still a child: but this
loss was alleviated by the kindness of his paternal aunt, who undertook
the care of his education from the time that he was nine years old. He
underwent some disadvantage, in being shifted about from one tutor to
another; but being of a studious turn, he made considerable progress in
the study of ancient and modern languages, Asiatic as well as European,
of mathematics, metaphysics, and other branches of learning; so that he
was found to be unusually well informed, on his admission at the
Dissenting Academy at Daventry, in 1752. His father and his aunt were
Calvinistic Dissenters, and Priestley was brought up in an unusually
strict observance of all the external duties of religion. He
acknowledges in his memoirs an obligation to this course of life, as
having early given him a serious turn of mind, but without recommending
a similar course for general adoption. As was natural, he imbibed the
principles of Calvinism; and suffered at one time severe uneasiness,
because he could not realize in his mind those feelings which he had
been taught to consider as the index of salvation. This we mention,
because it shows that his early prepossessions were diametrically
opposed to that system of religion to which he ultimately worked his
way.
For three years Priestley continued at Daventry, labouring sedulously in
studying to qualify himself for the ministry. At the end of that time,
he accepted an invitation to become assistant preacher to a dissenting
congregation at Needham Market, near Ipswich. His residence there, a
period of three years more, was one of considerable want and difficulty.
His stipulated salary amounted only to 40_l._, and was so ill paid, that
his receipts generally fell short of 30_l._: insomuch that, without
occasional assistance, procured from different charities by his friends,
he could scarcely have subsisted. This deficiency arose partly from the
poverty of the congregation, partly from his own unpopularity. His
religious views, which, during his abode at Daventry, had changed to
Arianism, did not accord with those of his hearers; and he laboured
under an impediment of speech. Yet, notwithstanding these unfavourable
circumstances, he says, “I was far from being unhappy at Needham. I
firmly believed that a wise Providence was disposing every thing for the
best, and I applied with great assiduity to my studies, which were
classical, mathematical, and theological. These required but few books.
As to experimental philosophy, I had always cultivated an acquaintance
with it, but I had not the means of prosecuting it.” The result of his
theological studies was a still more decided rejection of the doctrines
in which he had been brought up In his own words, “I had become, in
consequence of much pains and thought, persuaded of the falsity of the
doctrine of atonement, of the inspiration of the authors of the books of
scripture as writers, and of all idea of supernatural influence, except
for the purpose of miracles. But I was still an Arian, having never
turned my attention to the Socinian doctrine, and contenting myself with
seeing the absurdity of the Trinitarian system.”
Priestley’s situation was somewhat improved by an invitation to
Nantwich, in Cheshire, in 1758. He remained there for three years,
engaged in the double duty of preaching and keeping a school; and then
accepted an appointment as tutor of languages in the Dissenting Academy
newly established at Warrington. Not confining himself to the strict
letter of his duties, he composed and delivered lectures on the theory
of language, oratory, and criticism; on history in general, and on the
history, laws, and constitution of England. It is a remarkable instance
of his versatility and activity of mind, that, in addition to this
extensive course of study, he undertook to write his History of
Electricity, a subject with which he then was little acquainted, and
finished it within a year, though in the course of the work he had been
led into a large field of original experiments. After a residence of six
years, the situation affording him a bare livelihood, he removed to
Leeds, and took the charge of Mill Hill Chapel, in September, 1767.
At Leeds, Priestley resided for another period of six years, actively
employed in clerical and scientific labours. Here his experiments on
fixed air were undertaken, and published. He undertook a History of
Discoveries relating to Vision, Light, and Colours, as part of a
projected history of all the branches of experimental philosophy; but
the sale of this portion was discouraging, and he abandoned the rest of
the undertaking. He also published his well-known Chart of History, and
wrote an Essay on Government, with other pieces, in addition to a great
number of religious pamphlets. These various pursuits, with occasional
visits to London, made him well known to literary men; and, by the
friendship of Dr. Price, he was recommended to the Earl of Shelburne, as
well qualified to fill the station of a literary companion and friend.
In consequence, he removed to Calne in Wiltshire, close to that
nobleman’s seat, Bowood. Nominally filling the office of librarian, and
treated by Lord Shelburne with uniform respect and kindness, he had
access to the best society, both at Bowood and in London: he also had
the advantage of foreign travel. But at length a coldness grew up on the
part of his patron; and at the end of seven years the connection was
dissolved. By the terms of his agreement, Dr. Priestley became entitled
to an annuity of 150_l._, which was punctually paid. Each party bore
testimony to the honourable conduct of the other. The cause of this
estrangement never was avowed; but it is probable that the boldness with
which Priestley wrote in support of his peculiar metaphysical and
religious doctrines may have displeased Lord Shelburne.
Induced by motives of family connection, Dr. Priestley now took up his
residence at Birmingham. Local convenience and the society of various
distinguished men, among whom James Watt was pre-eminent, rendered that
town peculiarly suitable to his scientific pursuits, which, however,
were never suffered to occupy him to the exclusion of theology. He
undertook the ministry of a chapel. He revived the Theological
Repository, which had been commenced and discontinued at Leeds. He
composed and published his History of the Corruptions of Christianity.
This work involved him in a well-known controversy with Dr. Horsley, who
is commonly said to have owed his bishopric to his exertions in it.
Priestley pursued the dispute in a history of early opinions concerning
Jesus Christ; and for some time he wrote an annual pamphlet in answer to
the attacks on Unitarianism. His intimate friend, Dr. Price, was the
most distinguished among his opponents, and their controversy was
carried on with eminent decency and candour. It was published in 1778,
entitled “A free Discussion of the Doctrines of Materialism and
Necessity, in a Correspondence between Dr. Price and Dr. Priestley, &c.”
The Socinian tenets of the latter were again advocated in his General
History of the Christian Church to the Fall of the Western Empire. These
active labours in the field of controversy, backed by his general
reputation, caused Priestley to be regarded as the leading person among
the Dissenters, a body at that time distrusted by the government, and
disliked by a large portion of their fellow-countrymen. The agitation of
the repeal of the Test Act increased the prejudice against them, while
it gave Priestley a fresh motive for exertion. Loud was the outcry, and
bitter the hatred of the “Church and King” party. One of the clergy of
Birmingham attacked him from the pulpit. To him and to another he
replied in a series of Familiar Letters to the Inhabitants of
Birmingham. At length party rage grew so high, that a meeting (at which
Priestley was not present) being held by some persons, who looked
favourably on the commencement of the French Revolution, July 14, 1791,
to celebrate the anniversary of the destruction of the Bastile, the
house in which they assembled was attacked by an infuriated mob. Dr.
Priestley’s meeting-house and dwelling-house were the next objects of
outrage; and the latter, with his valuable library, philosophical
apparatus, papers, &c., was destroyed. The houses of several other
Dissenters were more or less injured. He recovered a certain
compensation for his losses; but the sum awarded, according to his
statement, fell two thousand pounds short of their real amount. The
liberality of his friends, however, more than made up the pecuniary
deficiency. The French testified a warm sense of his ill-usage; and on
the meeting of the National Convention, several of the departments
invited him to become a member of it. This compliment he wisely
declined.
Birmingham was no longer a pleasant, nor even a safe abode for the
philosopher. He removed to Hackney, where the congregation of Dr. Price
soon invited him to become the successor of his deceased friend. By
degrees he replaced his philosophical instruments, and resumed his
studies, hoping to finish his life without more removals. But as the
French Revolution advanced, and political dissension in England ran
higher and higher, his situation grew more unpleasant, and, in his
estimation, more dangerous. He found himself shunned at the meetings of
the Royal Society, and he ceased to attend them; he was harassed by
threats and insults; he believed the violence of the high church party
against him to be on the increase; he saw oppressive political
prosecutions instituted against others, and thought himself a likely
person to be marked for ruin. Above all, he found the evil repute into
which he had fallen an effectual bar to the favourable establishment of
his sons in England; and when they were gone to seek their fortunes in
America, he resolved to follow them. He landed at New York in June,
1794, and shortly after settled at Northumberland, a town about one
hundred and thirty miles N. W. of Philadelphia. There rejecting more
than one advantageous offer of situations in the University of
Philadelphia, he spent the remainder of life, continuing to the last his
philosophical and theological studies. The chief fruit of these latter
years was his General History of the Christian Church, in four volumes.
After a gradual decline of strength, he died, February 6, 1804.
The private character of Priestley was such as to command respect.
Modest, benevolent, pious, of studious and retired habits and
unimpeached morals, the worst his enemies had to say of him was, that he
taught heresy, and was an enemy of the established order of things. His
works, not including those on scientific subjects, have recently been
edited by Mr. Rutt, in twenty-five volumes 8vo., the first of which
contains his own memoirs, illustrated by notes by the editor, and very
numerous letters; and a catalogue of his publications in the order in
which they appeared. The same memoirs, written by himself, in an
unpretending and dispassionate style, and continued down to the author’s
death, by his son Joseph Priestley, appeared in 1805, with an appendix,
containing notices of his works and opinions. With respect to his
philosophical merits, the eloge pronounced on him by Cuvier to the
Institute, of which Priestley was an associate, in 1805, will command
attention, like every production of its distinguished author.
In the space to which we are restricted, it will be impossible to give
an adequate idea of the vast importance of Dr. Priestley’s chemical
discoveries: they are justly regarded as forming the basis of our
knowledge of pneumatic chemistry, and indeed of the science in general;
for upon one of them alone, that of oxygen gas, is founded our
acquaintance with the nature of air, earth, and water, and the same
discovery has served also to explain the action of fire.
Dr. Priestley’s residence at Leeds was near a brewery; and his first
pneumatic experiments were made on the carbonic acid gas, or _fixed
air_, largely generated during fermentation. Gradually pursuing the
subject, he examined various other aëriform bodies, and submitted to
experiment numerous substances which were convertible into, or capable
of yielding, air. These investigations led him to the discovery of new
gaseous bodies, both elementary and compound. So little cultivated had
been the field in which he commenced his researches, that he was under
the necessity of imagining and constructing new instruments, in order to
carry them on. To his inventive genius chemistry is indebted for the
pneumatic trough, the method of receiving and retaining gases over
mercury, and the process of combining and decomposing them by
electricity. “The very implements,” Dr. Henry remarks, in his Estimate
of the Philosophical Character of Dr. Priestley, “with which he was to
work were, for the most part, to be invented; and of the merits of those
which he did invent, it is a sufficient proof that they continue in use
to this day, with no very important modification. All his contrivances
for collecting, transferring, and preserving different kinds of air, and
for submitting those airs to the action of solid and liquid substances,
were exceedingly simple, beautiful, and effectual. They were chiefly,
too, the work of his own hands, or were constructed under his directions
by unskilled persons.” Dr. Priestley’s first publication on pneumatic
chemistry appeared in 1772; it was called “Directions for impregnating
Water with fixed Air,” &c. &c. In this work he proposed the use of a
condensing engine for the purpose of causing the water to dissolve a
larger quantity of the gas, and thus to prepare artificial mineral
waters: this plan, it is well known, is now practised to a great extent.
In the Philosophical Transactions for 1772, he announced the discovery
that air, which had been vitiated by respiration or the burning of
candles, was restored by the vegetation of plants; that air exposed to a
mixture of sulphur and iron filings, as had previously been done by
Hales, was diminished by about one-fourth or one-fifth in bulk, and that
the residual air was lighter than atmospheric air, and noxious to
animals. This diminished air he afterwards called phlogisticated air; it
is now named azotic, or nitrogen gas. The discovery of this fluid is
generally attributed to Dr. Rutherford, who, in his treatise “De Aëre
Mephitico,” also published in 1772, mentioned a few of its properties
without giving it any name. As Dr. Priestley’s papers were read before
the Royal Society so early as in March, it is not improbable that he was
the first discoverer of the gas in question. In 1774 appeared the first
of three volumes, entitled “Experiments and Observations on different
kinds of Air;” and these were followed by three more, entitled
“Experiments and Observations relating to various Branches of Natural
Philosophy, with a continuation of the Observations on Air:” the last of
these was published in 1786. This work contains a series of experiments,
unrivalled for their number, novelty, and importance.
Dr. Priestley’s greatest discovery, that of oxygen gas, which he called
dephlogisticated air, was made on the 1st of August, 1774, and announced
in the Philosophical Transactions for 1775. This gas he first procured
from red oxide of mercury, and afterwards from red oxide of lead, and
several other substances.
In 1776 Dr. Priestley’s Observations on Respiration were read before the
Royal Society. In these he showed that atmospheric air, during
inspiration, was diminished in quantity, and deteriorated in quality, by
the action of the blood upon it through the blood-vessels of the lungs.
He also proved that gases have the power of acting through bladders, and
one of his latest papers was on this curious subject: it appeared in the
fifth volume of the American Philosophical Transactions, and seems to
have been completely overlooked by later experimenters on the same
subject. Another of his early and important observations related to the
permanent mixture of gases of different densities, in cases in which
they do not combine; and he cited this circumstance to account for the
perfect mixture of the two gases which form the atmosphere, and which
are well known to be of different densities.
In addition to oxygen gas, already mentioned, Dr. Priestley also
discovered muriatic acid gas, sulphurous acid gas, fluoric acid gas,
nitrous oxide gas, ammoniacal gas, and carbonic oxide gas; but he
entirely mistook the nature of the last-mentioned body. He also showed
that muriatic acid gas and ammoniacal gas, when mixed, condense into
solid sal ammoniac. He must also have obtained chlorine gas, but it
escaped his notice, because, being received over mercury, it quickly
combined with it. Hydrogen gas and carbonic acid gas were known before
his time; but his experiments upon them greatly extended our
acquaintance with their properties. Nitrous gas, barely discovered by
Dr. Hales, was first investigated by Priestley, and applied by him to
eudiometry, a most important branch of chemical science originating with
himself.
In 1778, he pursued his experiments on the property of vegetables
growing in the light, to renovate impure air, and on the use of
vegetation in this part of the economy of nature. Chemistry is also
indebted to him for the method of decomposing metallic oxides by means
of hydrogen gas, and for noticing that this gas has the property of
dissolving iron. He observed also that lime is less soluble in hot than
cold water; and that when a solution of lime in cold water is heated,
part of the lime is deposited.
In the first volume of his work on air (p. 278), Dr. Priestley has
anticipated the idea of Dr. Arnott and Sir J. F. W. Herschel, that
electricity, acting on the brain and nerves, may excite muscular action.
Dr. Henry, in the memoir already quoted, has remarked, that facts are to
be met with in various parts of Dr. Priestley’s works that might have
given him a hint of the law, since unfolded by the sagacity of M.
Gay-Lussac, “that gaseous substances combine in definite volumes.” From
the same memoir we extract the following observations, in conclusion of
this short account of Dr. Priestley’s scientific labours:—“He greatly
enlarged our knowledge of the important class of metals, and traced out
many of their most interesting relations to oxygen and to acids. He
unfolded, and illustrated by simple and beautiful experiments, distinct
views of combustion; of the respiration of animals, both of the inferior
and higher classes; of the changes produced in organized bodies by
putrefaction, and of the causes that accelerate or retard that process;
of the importance of azote as the characteristic ingredient of animal
substances, observable by the action of dilute nitric acid on muscle and
tendon; of the functions and economy of living vegetables; and of the
relations and subserviency which exist between the animal and vegetable
kingdoms.”
[Illustration:
_Engraved by Rob^t. Hart._