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 elasticity and were condensed into a dew which lined the inside of the 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 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 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 1120th part, resisted the change, and in this residue he doubtless had a sample of the inert gas argon which was only recognized as a distinct entity more than a hundred years later. His last chemical paper, published in 1788, on the “Conversion of a mixture of dephlogisticated and phlogisticated air into nitrous acid by the electric spark,” describes 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 doctrine, he did not hold it with anything 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 hypothesis.
Early in his career Cavendish took up the study of heat, and had he promptly published his results he might have anticipated Joseph 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 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 Newton’s opinion that it “consists in the internal motion of the particles of bodies.” His “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 report signed by him and six others.
Cavendish’s last great achievement was his famous series of experiments to determine the density of the earth (Phil. Trans., 1798). The apparatus he employed was devised by the Rev. John Michell, though he had the most important parts reconstructed to his own designs; it depended on measuring the attraction exercised on a horizontal bar, suspended by a vertical wire and bearing a small lead ball at each end, by two large masses of lead. (See Gravitation.) The figure he gives for the specific gravity of the earth is 5.48, water being 1, but in fact the mean of the 29 results he records works out at 5.448. Other publications of his later years dealt with the height of an aurora seen in 1784 (Phil. Trans., 1790), the civil year of the Hindus (Id. 1792), and an improved method of graduating astronomical instruments (Id. 1809). Cavendish also had a taste for geology, and made several tours in England for the purpose of gratifying it.
A life by George Wilson (1818–1859), printed for the Cavendish Society in 1851, contains an account of his writings, both published and unpublished, together with a 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 Physical Laboratory at Cambridge, which was built by his kinsman the 7th duke of Devonshire.
CAVENDISH [Candish], THOMAS (1555?–1592), the third circumnavigator of the globe, was born at Trimley St Martin, Suffolk. On quitting Corpus Christi College, Cambridge (without a degree), he almost ruined himself by his extravagance as a courtier. To repair his fortune he turned to maritime and colonial enterprise, and in 1585 accompanied Sir Richard Grenville to America. Soon returning to England, he undertook an elaborate imitation of Drake’s great voyage. On the 21st of July 1586, he sailed from Plymouth with 123 men in three vessels, only one of which (the “Desire,” of 140 tons) came home. By way of Sierra Leone, the Cape Verde Islands and C. Frio in Brazil, he coasted down to Patagonia (where he discovered “Port Desire,” his only important contribution to knowledge), and passing through Magellan’s Straits, fell upon the Spanish settlements and shipping on the west coast of South and Central America and of Mexico. Among his prizes were nineteen vessels of worth, and especially the treasure-galleon, the “Great St Anne,” which he captured off Cape St Lucas, the southern extremity of California (November 14, 1587). After this success he struck across the Pacific for home; touched at the Ladrones, Philippines, Moluccas and Java; rounded the Cape of Good Hope; and arrived again at Plymouth (September 9–10, 1588), having circumnavigated the globe in two years and fifty days. It is said that his sailors were clothed in silk, his sails were damask, and his top-mast covered with cloth of gold. Yet by 1591 he was again in difficulties, and planned a fresh American and Pacific venture. John Davis (q.v.) accompanied him, but the voyage (undertaken with five vessels) was an utter failure, much of the fault lying with Cavendish himself, who falsely accused Davis, with his last breath, of deserting him (May 20, 1592). He died and was buried at sea, on the way home, in the summer of 1592.
See Hakluyt’s Principal Navigations, (a) edition of 1589, p. 809 (N. H.’s narrative of the voyage of 1586–1588); (b) edition of 1599–1600, vol. iii. pp. 803-825 (Francis Pretty’s narrative of the same); (c) edition of 1599–1600, vol. iii. pp. 251-253 (on the venture of 1585); (d) edition of 1599–1600, vol. iii. pp. 845-852 (John Lane’s narrative of the last voyage, of 1591–1592); also Stationers’ Registers (Arber), vol. ii. pp. 505-509; the Molyneux Globe of 1592, in the library of the Middle Temple, London, and the Ballads in Biog. Brit., vol. i. p. 1196.
CAVENDISH, SIR WILLIAM (c. 1505–1557), founder of the English noble house of Cavendish, was the younger brother of George Cavendish (q.v.). His father, Thomas, was a descendant of Sir John Cavendish, the judge, who in 1381 was murdered by Jack Straw’s insurgent peasants at Bury St Edmunds. Of William’s education nothing seems known, but in 1530 he was appointed one of the commissioners for visiting monasteries; he worked directly under Thomas Cromwell, whom he calls “master” and to whom many of his extant letters are addressed. In 1541 he was auditor of the court of augmentations, in 1546 treasurer of the king’s chamber, and was knighted and sworn of the privy council. Under Edward VI. and Mary he continued in favour at court; during the latter’s reign he partially conformed, but on the occasion of the war with France he with other Derbyshire gentlemen refused the loan of £100 demanded by the queen. He died in 1557. Cavendish acquired large properties from the spoils of the monasteries, but in accordance with the wish of his third wife Elizabeth he sold them to purchase land in Derbyshire. This wife was the celebrated “building Bess of Hardwick,” daughter of John Hardwicke, of Hardwicke, Derbyshire; she completed the original building of Chatsworth House,—begun in 1553 by her husband,—of which nothing now remains. Her fourth husband was George Talbot, 6th earl of Shrewsbury. By her Cavendish had six children; an elder son who died without issue; William, who in 1618 was created earl of Devonshire; Charles, whose son William became 1st duke of Newcastle;
