Gassiot, John Peter

(b. London, England, 2 April 1797:d. Isle of Wight, 15 August 1877),

electricity.

Gassiot, a wealthy wine merchant, was elected a fellow of the Royal Society in 1840 and was one of the founders of the Chemical Society in 1841. He also helped to endow the Kew observatory and for many years was the chairman of the Royal Society’s Kew Observatory Committee. In 1863 Gassiot was awarded the Royal Society’s Royal Medal in recognition of his work on voltaic electricity and on the discharge of electricity through gases at low pressure.¹.

In the late 1830’s, when Gassiot began his investigations, the identity of static and voltaic electricity seemed likely. But if this were so, voltaic, like static, electricity ought to produce sparks before the circuit was completed. In 1839 Gassiot showed that even with a battery of 1,024 Daniell cells no sparks occurred. But if he used these cells either to charge a bank of nine Leyden jars or in conjunction with a circuit interrupter and transformer, he could produce sparks before contact. He also obtained sparks with a Zamboni dry pile of 10,000 cells and, later, of 1,000 cells.² But in 1843, using a massive battery of 3,520 zinc-copper rainwater cells, he produced sparks through 0.020 inch of air. Gassiot attributed his success to his great care in insulating the individual cells to prevent the loss of their electrical tension.³.

At that time it had not been decided whether voltaic electricity is produced by contact between metals or by chemical reaction. In an attempt to decide this question Gassiot showed in the same paper that “the elements constituting the voltaic battery, when arranged in a series, assume polar tension before the circuit is completed….” Yet a few months later he concluded that “to produce static effects in a voltaic battery, it is indispensible that the elements should be such as can combine by their chemical affinities….” Furthermore, “in all the experiments I made, the higher the chemical affinities of the elements used, the greater was the evidence of tension.” These discoveries gave further evidence to support the decision in favor of the chemical theory that had already been reached in 1839 by Gassiot’s friend Michael Faraday.⁴.

Faraday’s discovery in 1838 of the negative dark space had revived interest in the glow discharge caused by conduction of electricity through gases at low pressure,⁵ but Gassiot’s interest in this discharge was directly stimulated by W. R. Grove’s almost incidental report in 1852 that the discharge was “striated by transverse non-luminous bands….”⁶ In his initial investigations Gassiot showed that if enough care were exercised to achieve a sufficiently low pressure, striations could be produced in the Torricellian vacuum. Next he demonstrated that both a static electric machine and a Ruhmkorff coil with a Grove cell produced a striated discharge. This once again confirmed the identity of these two electricities.⁷ He also noticed that a powerful electromagnet divided the striations into what appeared to be two distinct columns.⁸ The paper in which Gassiot announced these discoveries was honored as the Royal Society’s Bakerian lecture for 1858.

During the next two years Gassiot continued his efforts to obtain the striations, which he thought were caused by “pulsations or impulses of a force acting on highly attenuated but a resisting medium…, “⁹ Although his theory here was not correct, his investigations produced much new information. First, because his 3,520-cell battery or a 400-cell Grove battery unassisted did produce striations, it was clear that the “induction coil is not necessary for the production of the striae…”¹⁰ Next Gassiot demonstrated experimentally that the striae exist only within a narrower range of pressure and temperature than the luminous discharge itself; that a sufficiently low pressure not only ends the discharge but also that this relative vacuum does not conduct electricity; that changes in the electrical resistance of the external circuit change the discharge; and that at least sometimes the luminous discharge; is actually intermittent even though it appears to be continuous.¹¹.

In Gassiot’s final group of experiments on the gaseous discharge he showed that in a series circuit containing two discharge tubes, if a magnet is used to interrupt one discharge, the electrical current in both is completely disrupted;¹² that excitation of a spiral “carbonic acid vacuum tube…” gives a brilliant white light;¹³ that there is a mechanical disruption of the metal in the negative electrode;¹⁴ and that changes in the external resistance in the electrical circuit also change the striae in the discharge.¹⁵ Gassiot also perfected a rotating and vibrating mirror technique that he used to reconfirm his discovery that the discharge, under certain conditions, is intermittent. His last papers generally concerned improvements in spectroscopes, In particular he designed and had constructed a spectroscope with nine glass prisms and another with eleven prisms filled with carbon disulfide, which he presented to Kew observatory.¹⁶

NOTES

1. “Anniversary Meeting—President’s Address,” in Proceedings of the Royal Society, 13 (1864), 183-185.

2. “An Account of Experiments Made With the View of Ascertaining the possibility of Obtaining a spark Before the Circuit of the Voltaic Battery Is Completed,” in Philosophical Transactions of the Royal Society, 130 (1840), 183-192.

3. “A Description of an Extensive Series of the Water Battery,” ibid., 134 (1844), 39-42.

4.Ibid.; see also Michael Faraday, Experimantal Researches in Electricity, par. 2053.

5.Ibid., pars. 1544-1560.

6. “On the Electro-Chemical Polarity of Gases,” in Philosophical Transactions of the Royal Society, 142 (1852), 100.

7. “On the Stratification and Dark Band in Electrical Discharges as Observed in the Torricellian Vacua,” ibid., 148 (1858), 6.

8.Ibid., p. 15.

9.Ibid., p. 14.

10. “On the Electrical Discharge in Observed in of the Voltaic Battery,” in Proceedings of the Royal Socity, 10 (1860), 36-37.

11. “On the Stratification in Electrical Discharges Observed in Torricellian and Other Vacua—Second Communication,” in PhilosoPhicalggg Transactions of the Royal Society,149 (1859), 137-160.

12. “On the Interruption of the Voltaic Discharge in vacuo by Magnetic Force,” in Proceedings of the Royal Society, 10 (1860), 269-274.

13.Ibid., p. 432.

14.British Association Report (London, 1861), section 2, 38-39.

15. “Experimental Investigations on the Stratified Appearance in Electrical Discharges,” in Proceedings of the Royal Society, 12 (1863), 329-340.

16.Philosophical Magazine, 27 (1864), 143-144.

BIBLIOGRAPHY

I. Original Works. Gassiot’s papers are listed in Poggendorff, I, 849-850, and III, 495; and in Royal Society, Catalogue of Scientific Papers, II. 779-780; VII, 741-742 Michael Faraday assisted Gassiot with some of his experiments on gas discharge. Faraday’s notes on these experiments are reprinted in Faraday’s Diary. VII (London, 1936), 412-461. There is no collected edition of his works.

II Secondary Liteature. There is no biography of Gassiot, Biographical information is based on the article on him in the Dictionary of National Biography, VII, 935-936, and on the references given there. The most useful survey of his scientific work is contained in the speech made by Edward Sabine, president of the Royal Society, in presenting Gassiot’s Royal Medal. It is reprinted in Proceeding of the Royal Society, 13 (1864), 36-39. The debate about the “contact” and “chemical” theories of the voltaic battery is discussed in Edmund Whittaker, History of the Theories of Aether and Electricity, I (New York, 1960), 180—184. Whittaker’s brief account of the work on conduction of electricity through rarefied gases, pp. 348-366, can be supplemented by J. J. Thomson, Conduction of Electricity Through Gases, 2 vols. (3rd ed., Cambridge, 1933).

Edgar W. Morse