CAVENDISH, HENRY, was the younger son of Lord Charles Cavendish, the brother of the great-grandfather of the present Duke of Devonshire, and was born at Nice, October 10, 1731. Having received his preliminary education in a private school at Hackney, he proceeded to Cambridge and matriculated December 18, 1749. He remained there till 1753, but did not graduate. He had during the life of his father a very moderate income, and his relatives wero estranged from him by his determination not to enter upon public or political life ; with the exception of an uncle, who, on his return from abroad in 1773, not being pleased with the conduct of the family towards Cavendish, made the latter heir to his fortune, which was vary large. Cavendish devoted himself to mathematics and chemistry, to which his attention was probably turned by his father, who was himself a cultivator of the sciences; but his success, or at least its evidence, did not come very early, for ho was more than 35 years of age before he published anything. He lived a retired life, and never married ; his manners seem to have been eccentric, and to strangers very reserved. Indeed this reserve extended far beyond what would by ordinary people be considered as strangers. It is said by Dr. Children (Wilson a Life of Cavendish ') that he was ao shy towards females that be would never see even a female domestic, and "if an unfortunate maid showed herself, she was immediately dismissed." In order to avoid communication with his servants, it is added by I Lord Brougham, "he used to order his dinner daily by a note, which he left at a certain hour on the hall table, whence the housekeeper was to take it." Hia library, Biot says, was immense, and he fixed it at a distance from his own residence, that he might not be disturbed by those who came to consult it. His friends ware allowed to take books, and he himself never withdrew a book without giving a receipt for it. He died February 24, 1810, leaving more than a million sterling among different relations.
Of Cavendish as a philosopher, those who judge by the quantity of brilliant discoveries will not be able to form any opinion. His writings consist of a few papers in the 'Philosophical Transactions,' from 1766 to 1809. But in these papers we find methods and results which have occasioned his being sometimes called the Newton of Chemistry. Without such hyperbole, it may safely be said that he was the first, and one of the most useful, of those who laid the foun dation of the science in its modern form. At the time when his first papar appeared, pneumatic chemistry had hardly an existence. It is true that different gases were known, that is, had been obtained as results of chemical processes; but they were not recognised as distinct substances. It was thought they consisted of common air mixed with foreign matter; and it was not imagined for instance, that the, inflammable air produced by operating with one substance was the same as that from another. In 1766, Cavendish for the first time asserted and demonstrated that the fixed air (carbonic acid gas) was the same, whatever was the substance from which it was derived, and the same for the inflammable air (hydrogen), and that neither had the specific gravity of common air. He investigated for the first time the
principal properties of the latter substance, and noticed the moisture which results from its combustion. In 1784, he completed the syn thetical formation of water; that is, he found the moisture above mentioned to be simple water, and discovered that the remaining element of air, now therefore called nitrogen, was the constituent of nitric acid. He produced this substance by passing the electric spark through air over mercury, and saturating the result with a solution of potash, by which he obtained nitrate of potash, commonly called nitre. It has been keenly debated whether the discovery of the com position of water should be assigned to Cavendish or to Watt ; but the result of the sifting which the question has undergone, appears to be that each arrived at the discovery by a different method and with out being at all cognisant of the other's investigations. Cavendish's well-known experiment for the sletermivation of the earth's density is described under ATTRACTION in the ARTS AND SCIENCES. Div. Caven dish also wrote on the civil year of the Hindus, and on the division of astronomical instruments, and various papers on electricity.
Wa resist the temptation to swell this article to an extent propor tionate to what the reputation of Cavendish deserves. The funda mentality, if we may use such a word, of his chemical results has not been surpassed by those of any other discoverer in chemistry. But he deserves fame for the great accuracy of his experiments, and the (then) unequalled aoundness of his views. One writer asserts that every sentence he has written will bear microscopic examination. A French writer admits (we should say affirms) that he furnished Lavoisier with the materials of his system ; and Sir Hurnpbry Davy in a lecture delivered shortly after the death of Cavendish, speaks as follows : "His processes were all of a finished nature, perfected by the hand of a master; they required no correction; and though many of them were performed in the very infancy of chemical science, yet their accuracy and their beauty have remained unimpaired amidst the of atmorary." The discoveries of Cavendish were finished' 1 Eel:Zed his substanore both by analysis and synthesis; ascertained that the weight of his product was the sum of that of Its components, and determined Ito specific gravity. lie was the first who carried the min I end methods of • mathematician into the field from which the alcherulat had Dot long retired, and in which the speculator still remained. And when we Pay the mind and methods of a mathema titian. we do not deny that the inductive philosopher had already been there; but it mu to remark phenomena, and not to measure quanthisa.
(Geo. M.D., Lift of SAe Hon. Henry Carcndish, including Asieges 41 As mess important scientific papers; printed for the Cavendish Society, Loud., 1551 ; Mot, Art. amanitas in Biographic l'airsessile. *NJ