INGENHOUSZ, JOHN, an eminent physician and na-
tural philosopher, was born at Breda in 1730. He was
first established in medical practice there, but removed to
London in 1767, particularly with a view to study the im-
proved methods of inoculation then recently introduced.
Having become acquainted with Sir John Pringle, at that
time President of the Royal Society, he was by him re-
commended to the Austrian ambassador, for the purpose of
inoculating the Imperial family at Vienna, the Empress
Maria Theresa having lost two of her children by the na-
tural small-pox. He accepted this engagement in 1768,
and having been perfectly successful in his operations, he
was remunerated by the grant of a pension of £600 a-year
for life, together with the titles of Aulic Counsellor and
Physician to the Imperial Family. He was also consulted,
in his medical capacity, by many others of the most dis-
tinguished personages at Vienna, and he enjoyed the par-
ticular esteem of the Emperor Joseph II., who was fond of
receiving him in his cabinet, and of witnessing the exhibi-
tion of a variety of physical experiments, with which it was
always the delight of Ingenhousz to amuse and instruct his
acquaintance of both sexes. The following spring he went
to Italy, and inoculated the Grand Duke of Tuscany. He
was made a Fellow of the Royal Society in May 1769; but
he appears to have remained some years in Italy, for he
was at Leghorn in January 1773; in March he dates from
Salzburg; and in November 1775 from Vienna. The
next year he was in London; and, in the winter of 1779,
he went to Paris. The latter part of his life he spent prin-
cipally in England, which, notwithstanding his dislike to
the chillness of the climate, was always his favourite resi-
dence, and "where he enjoyed during many years," to use
his own words, "that felicity which a free and independent
man finds in the pursuit of knowledge and wisdom, in the
society and friendly intercourse of those who have distin-
guished themselves by their learning."
Dr Ingenhousz was cheerful in his disposition, and often
playful in his conversation. Though his pursuits were
chiefly scientific, he was not destitute of taste for literature
and poetry. He had a particular predilection for Lucan,
and for the Cardinal de Polignac, and would frequently
recite passages from their poems with great energy, and
with a strong German accent. Nor did he disdain the
comforts of commercial opulence, and he was often a visitor
at the magnificent villa of the late Mr Rucker of Roham-
pton. He had been introduced there by his friend Dr
Brocklesby, who was in many respects of a perfectly con-
genial disposition, and who had great pleasure in prevail-
ing on him to partake occasionally of his own hospitality,
when his table would otherwise have been solitary. He
died the 7th September 1799, at Bow Wood, in Wilts-
hire, the house of the Marquis of Lansdown, who had long
known and esteemed him.
Dr Ingenhousz's principal publications are, 1. Experi-
ments on the Torpedo. Phil. Trans. 1775, p. 1. Mr
Walsh had lately gained considerable reputation by his ac-
count of the effects of the torpedo. These experiments,
which were made off Leghorn, in company with Dr Drum-
mond, are merely illustrative of the properties of that ani-
mal, which are now better known; and they afford no de-
cided test of the electrical nature of the phenomena.
2. Methods of Measuring the Bulk of Mixtures of Com-
mon Air, and Nitrous Air, with Experiments on Platina.
Phil. Trans. 1776, p. 257. The eudiometrical apparatus
is described as an improvement on Fontana's. The ex-
periments are intended to shew that platina is not an alloy of
iron and gold, since it may be deprived of all magnetic
properties by repeated cupellation.
3. A Way of Lighting a Candle by an Electrical Spark.
Phil. Trans. 1778, p. 1022. A very small charged jar
setting fire to pulverised resin, strewed on cotton.
4. On the Electrophorus, p. 1027. This is a Bakerian
lecture, read by appointment of the President and Council
of the Royal Society, relating to the instrument then lately
invented by Professor Volta, and which had been made
known to the author by the Archduke Ferdinand. Its ac-
tion is explained upon the elementary principles of the
Franklinian theory. The next article in the volume con-
tains some experiments of Mr Henly in confirmation of the
doctrines here advanced.
5. On a New Inflammable Gas. Phil. Trans. 1779,
p. 576. A powerful explosion is produced by the detona-
tion of the vapour of a single drop of ether with oxygen
gas. The author takes occasion to investigate the elasti-
city of the gas evolved by the detonation of gunpowder;
and agrees with Bernoulli in estimating it as equivalent
to near 2500 atmospheres. It may here be remarked, that
notwithstanding Bernoulli's general accuracy, and great
mathematical talents, he has fallen into a very singular
error, in comparing the force of gunpowder with the daily
labour of men; and has accidentally made the force of one
pound equivalent to the daily work of 100 men, while, in
fact, the force of 40 pounds is only equivalent to the daily
labour of a single man.
6. On a Mode of Suspending Magnetical Needles, p. 537.
Proposing that a hollow needle should be immersed in lin-
seed oil, so as to press with a small portion of its weight
only on its axis, in order that the friction may be greatly
diminished.
7. Improvements in Electricity, p. 661. On plate ma-
ingots of glass and pasteboard, and on a riband machine. A Bakerian lecture.
8. Experiments on Vegetables. London, 1779. This volume is chiefly occupied by the detailed proofs of the author's principal discovery, that vegetables in general pour out a portion of oxygen gas in the sunshine, while they rather diminish its proportion at night and in the shade. It is dedicated to Sir John Pringle, and was translated into French by the author. Paris, 1786. Second edition, 2 vols. 8vo. 1787-9. Latin by Scherer. Vienna, 1786. Dutch by Dr Van Breda, of Delft, with others of his works.
9. On the Salubrity of the Air at Sea, and at Places far removed from the Sea. Phil. Trans. 1780, p. 554. From the imperfection of the test employed, it was easy to imagine that some differences were discovered, which subsequent observations have shewn to have no existence.
10. Nouvelles Expériences et Observations, 2 vols. 8vo. Paris. On different subjects of natural philosophy. In German by Molitor, Vermischte Schriften. Vienna, 1784.
11. On the Influence of the Vegetable Kingdom in the Animal Creation. Phil. Trans. 1782, p. 426. Asserting the accuracy of his experiments, and denying some statements of Dr Priestley; advancing, in particular, many arguments to prove that the air obtained is really supplied by the vegetables, and not by the water in which they are usually immersed, in order to collect it. Dr Ingenhousz was, on all occasions, anxious to support his claim to this very interesting discovery; and he insisted that Priestley's earlier experiments, on the green matter contained in stagnant water, had little or nothing in common with his own, because that matter was, in fact, of an animal nature. He was in the habit of collecting the gas from cabbage leaves, and of keeping it bottled up in his pocket; and he was prepared with some coils of iron wire fastened into the corks, in order to exhibit the brilliant phenomenon of their combustion to his friends; the public being at that time less accustomed to this dazzling exhibition, than it has become in later years, when elementary lectures on chemistry have been more commonly addressed to mixed audiences than heretofore.
12. Essay on the Food of Plants, 8vo. London, 1798. From the French.
13. Dr Ingenhousz also inserted some essays in different volumes of the Journal de Physique; but they possess less originality and importance than his English publications.
(Chalmers's Biographical Dictionary, xix. London, 1815, 8vo; Kesteloot in Biographie Universelle, xxi. Paris, 1818, 8vo.) (L. L.)