Dictionary of National Biography, 1885-1900/Gassiot, John Peter
GASSIOT, JOHN PETER (1797–1877), scientific writer, was born in London 2 April 1797. He went to school at Lee, and afterwards was for a few years a midshipman in the royal navy. He married in 1818, and had nine sons and three daughters, six of whom survived him. Gassiot was a member of the firm of Martinez, Gassiot, & Co., wine merchants, of London and Oporto. He was a munificent friend to science. His house on Clapham Common was always open to his fellow-workers, and was provided with the best apparatus for scientific experiments. He was the chairman of the committee of Kew Observatory, which he helped to endow; he also endowed the Cowper Street Middle Class School, London, to which he bequeathed valuable apparatus; he founded the Royal Society Scientific Relief Fund; and was one of the founders of the Chemical Society in 1847. He was also a magistrate of Surrey. Gassiot wrote forty-four papers in various scientific periodicals; the first an ‘Account of Experiments with Voltameters having Electrodes exposing different Surfaces,’ appearing in the Electrical Society's ‘Transactions,’ 1837–40, pp. 107–10; and the last ‘On the Metallic Deposit obtained from the Induction Discharge in Vacuum Tubes,’ in the British Association Report for 1869, p. 46. His work was almost entirely concerned with the phenomena of electricity.
In the ‘Philosophical Transactions’ for 1840 and 1844, Gassiot, who was a fellow of the Royal Society, described experiments made with a view to obtaining an electric spark before the circuit of the voltaic battery was completed. For these experiments he constructed batteries of immense power, commencing with a water battery of five hundred cells, and ending with 3,500 Leclanché cells. In 1844 he published perhaps his most important research—his experiments with a battery of one hundred Grove's cells, specially made of glass, with long glass stems, so that each cell was effectually insulated from its neighbours. With this battery Gassiot was able to prove that the static effects of a battery increase with its chemical action, a fact which had been denied or doubted by other experimenters.
In 1844 Gassiot showed by experimenting with delicate micrometer apparatus (Philosophical Magazine for October) that Grove's arguments against the contact theory of electricity were correct. In conducting a series of experiments upon the decomposition of water by electricity, Gassiot showed that when the liquid was under a pressure of 447 atmospheres it offered no extra resistance to the passage of the electric current. In 1852 Grove discovered the dark bands, striæ, or stratification, of the electric discharge; and to the study of this phenomenon he devoted much time and money. He showed that these striæ accompany all electric discharges in vacuum tubes, and that they occur equally well when, as is the case when the discharge takes place in the Torricellian vacuum of a barometer, no contact-breaker is employed. His researches on this matter formed the subject of the Bakerian lecture before the Royal Society in 1858. Gassiot further proved that when vacuum tubes are exhausted of their gases beyond a certain limit, the electric discharge will not pass at all. Gassiot died in the Isle of Wight, 15 Aug. 1877.[Journ. of Chemical Soc. for 1878, xxxiii. 227; Nature for September 1877, pp. 388, 399; Royal Soc. Cat. of Scientific Papers; information communicated by relatives.]