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CAVENDISH, HENRY (1731-1810)

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Originally appearing in Volume V05, Page 581 of the 1911 Encyclopedia Britannica.
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CAVENDISH, See also:HENRY (1731-1810) , See also:English chemist and physicist, See also:elder son of See also:Lord See also:Charles Cavendish, See also:brother of the 3rd See also:duke of See also:Devonshire, and See also:Lady See also:Anne See also:Grey, daughter of the duke of See also:Kent, was See also:born at See also:Nice in See also:October 1731. He was sent to school at See also:Hackney in 1742, and in 1749 entered See also:Peter-See also:house, See also:Cambridge, which he See also:left in 1753, without taking a degree. Until he was about See also:forty he seems to have enjoyed a very mode-See also:rate See also:allowance from his See also:father, but in the latter See also:part of his See also:life he was left a See also:fortune which made him one of the richest men of his See also:time. He lived principally at Clapham See also:Common, but he had also a See also:town-house in Bloomsbury, while his library was in a house in See also:Dean See also:Street, Soho; and there he used to attend on appointed days to lend the books to men who were properly vouched for. So methodical was he that he never took down a See also:volume for his own use without entering it in the See also:loan-See also:book. He was a See also:regular attendant at the meetings of the Royal Society, of which he became a See also:fellow in 1760, and he dined every See also:Thursday with theclub composed of its members. Otherwise he had little inter-course with society; indeed, his See also:chief See also:object in life seems to have been to avoid the See also:attention of his See also:fellows. With his relatives he had little intercourse, and even Lord See also:George Cavendish, whom he made his See also:principal See also:heir, he saw only for a few minutes once a See also:year. His See also:dinner was ordered daily by a See also:note placed on the See also:hall-table, and his See also:women servants were instructed to keep out of his sight on See also:pain of dismissal. In See also:person he was tall and rather thin; his See also:dress was old-fashioned and singularly See also:uniform, and was inclined to be shabby about the times when the precisely arranged visits of his tailor were due. He had a slight hesitation in his speech, and his See also:air of timidity and reserve was almost ludicrous. He was never married.

He died at Clapham on the 24th of See also:

February 1810, leaving funded See also:property See also:worth 700,000, and a landed See also:estate of £8000 a year, together with See also:canal and other property, and £50,000 at his bankers. Cavendish's scientific See also:work is distinguished for the wideness of its range and for its extraordinary exactness and accuracy. The papers he himself published See also:form an incomplete See also:record of his researches, for many of the results he obtained only became generally known years after his See also:death; yet in spite of the See also:absence of anything approaching self-See also:advertisement he acquired a very high reputation within his own See also:country and abroad, recognized by the See also:Institute of See also:France in 1803 when it See also:chose him as one of its eight See also:foreign associates. See also:Arsenic formed the subject of his first recorded investigation, on which he was engaged at least as See also:early as 1764, and in 1766 he began those communications to the Royal Society on the See also:chemistry of gases, which are among his chief titles to fame. The first (Phil. Trans., 1766) consists of " Three papers containing experiments on Factitious Airs," dealing mostly with " inflammable air " (See also:hydrogen), which he was the first to recognize as a distinct substance, and " fixed air " (See also:carbon dioxide). He determined the specific gravity of these gases with reference to common air, investigated the extent to which they are absorbed by various liquids, and noted that common air containing one part in nine by volume of fixed air is no longer able to support See also:combustion, and that the air produced by See also:fermentation and putrefaction has properties identical with those of fixed air obtained from See also:marble. In the following year he published a See also:paper on the See also:analysis of one of the See also:London See also:pump-See also:waters (from Rathbone See also:Place, See also:Oxford Street), which is closely connected with the See also:memoirs just mentioned, since it shows that the calcareous See also:matter in that See also:water is held in See also:solution by the "fixed air" See also:present and can be precipitated by See also:lime. See also:Electrical studies seem next to have engaged his attention, and in 1771 and 1772 he read to the Royal Society his " See also:Attempt to explain some of the principal phenomena of See also:electricity by an elastic fluid," which was followed in 1775 by an " Attempt to imitate the effects of the See also:Torpedo (a See also:fish allied to the See also:ray)" (Phil. Trans., 1776). But these two memoirs contain only a part of the electrical researches he carried out between 1771 and 1781, and many more were found after his death in a number of sealed packets of papers. The contents of these for a See also:long time remained unknown, but ultimately by permission of the duke of Devonshire, to whom they belonged, they were edited by See also:James Clerk See also:Maxwell and published in 187g by the Cambridge University See also:Press as the Electrical Researches of the Hon.

Henry Cavendish. About 1777 or 1778 he resumed his pneumatic inquiries, though he published nothing on the subject till 1783. In that year he described a new eudiometer to the Royal Society and detailed observations he had made to determine whether or not the See also:

atmosphere is See also:constant in See also:composition; after testing the air on nearly 60 different days in 1781 he could find in the proportion of See also:oxygen no difference of which he could be sure, nor could he detect any sensible variation at different places. Two papers on " Experiments with Airs," printed in the Phil. Trans. for 1784 and 1785, contain his See also:great discoveries of the See also:compound nature of water and the composition of nitric See also:acid. Starting from an experiment, narrated by See also:Priestley, in which See also:John Warltire fired a mixture of common air and hydrogen by electricity, with the result that there was a diminution of volume and a deposition of moisture, Cavendish burnt about two parts of hydrogen with five of common air, and noticed that almost all the hydrogen and about one-fifth of the common air lost their See also:elasticity and were condensed into a See also:dew which lined the inside of the See also:vessel employed. This dew he judged to be pure water. In another experiment he fired, by the electric spark, a mixture of hydrogen and oxygen (dephlogisticated air), and found that the resulting water contained nitric acid, which he argued must be due to the See also:nitrogen present as an impurity in the oxygen (" phlogisticated air with which it the dephlogisticated air] is debased "). In the 1785 paper he proved the correctness of this supposition by showing that when electric See also:sparks are passed through common air there is a shrinkage of volume owing to the nitrogen uniting with the oxygen to form nitric acid. Further, remarking that little was known of the phlogisticated part of our atmosphere, and thinking it might fairly be doubted " whether there are not in reality many different substances confounded together by us under the name of phlogisticated air," he made an experiment to determine whether the whole of a given portion of nitrogen (phlogisticated air) of the atmosphere could be reduced to nitric acid. He found that a small fraction, not more than -14-uth part, resisted the See also:change, and in this See also:residue he doubtless had a See also:sample of the inert See also:gas See also:argon which was only recognized as a distinct entity more than a See also:hundred years later. His last chemical paper, published in 1788, on the " See also:Conversion of a mixture of dephlogisticated and phlogisticated air into nitrous acid by the electric spark," describes See also:measures he took to authenticate the truth of the experiment described in the 1785 paper, which had " since been tried by persons of distinguished ability in such pursuits without success." It may be noted here that, while Cavendish adhered to the phlogistic See also:doctrine, he did not hold it with any-thing like the tenacity that characterized Priestley; thus, in his 1784 paper on " Experiments on Air," he remarks that not only the experiments he is describing, but also " most other phenomena of nature seem explicable as well, or nearly as well," upon the Lavoisierian view as upon the commonly believed principle of phlogiston, and he goes on to give an explanation in terms of the antiphlogistic See also:hypothesis.

Early in his career Cavendish took up the study of See also:

heat, and had he promptly published his results he might have anticipated See also:Joseph See also:Black as the discoverer of latent heat and of specific heat. But he made no reference to his work till 1783, when he presented to the Royal Society some " Observations on Mr Hutchins's experiments for determining the degree of See also:cold at which quicksilver freezes." This paper, with others published in 1786 and 1788, is concerned with the phenomena attending the freezing of various substances, and is noteworthy because in it he expresses doubt of the supposition that " the heat of bodies is owing to their containing more or less of a substance called the matter of heat," and inclines to See also:Newton's See also:opinion that it " consists in the See also:internal See also:motion of the particles of bodies." His " See also:Account of the Meteorological Apparatus used at the Royal Society's House " (Phil. Trans., 1776) contains remarks on the precautions necessary in making and using thermometers, a subject which is continued in the following year in a See also:report signed by him and six others. Cavendish's last great achievement was his famous See also:series of experiments to determine the See also:density of the See also:earth (Phil. Trans., 1798). The apparatus he employed was devised by the Rev. John See also:Michell, though he had the most important parts reconstructed to his own designs; it depended on measuring the attraction exercised on a See also:horizontal See also:bar, suspended by a See also:vertical See also:wire and bearing a small See also:lead See also:ball at each end, by two large masses of lead. (See See also:GRAVITATION.) The figure he gives for the specific gravity of the earth is 5.48, water being i, but in fact the mean of the 29 results he records See also:works out at 5.448. Other publications of his later years dealt with the height of an See also:aurora seen in 1784 (Phil. Trans., 1790), the See also:civil year of the See also:Hindus (Id. 1792), and an improved method of graduating astronomical See also:instruments (Id. 1809).

Cavendish also had a See also:

taste for See also:geology, and made several See also:tours in See also:England for the purpose of gratifying it. A life by George See also:Wilson (1818–1859), printed for the Cavendish Society in 1851, contains an account of his writings, both published and unpublished, together with a See also:critical inquiry into the claims of all the alleged discoverers of the composition of water. Some of his instruments are preserved in the Royal Institution, London, and his name is commemorated in the Cavendish See also:Physical Laboratory at Cambridge, which was built by his kinsman the 7th duke of See also:Devon-See also:shire.

End of Article: CAVENDISH, HENRY (1731-1810)

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