DUKE 
 
 UNIVERSITY 
 
 LIBRARY 
 
 FRANK BAKER COLLECTION 
 
 OF 
 
 WESLEYANA 
 
 AND 
 
 BRITISH METHODISM 
 
NEW EXPERIMENTS 
 
 o N 
 
 ELECTRICITY. 
 
 W H H R E I N 
 
 THE CAUSES OF THUNDER AND LIGHTNING 
 
 AS WELL AS THE CONSTANT STATE OF 
 
 Pofitive or negative Eledricity in the Air or 
 Clouds, are explained^ 
 
 WITH 
 
 Experiments on Clouds of Powders and Vapours 
 
 ARTIFICIALLY DIFFUSED IN THE AIR. 
 ALSO 
 
 A DESCRIPTION OF 
 
 A DOUBLER of ELECTRICITY, 
 
 AND OF THE MOST 
 
 SENSIBLE ELECTROMETER YET CONSTRUCTED. 
 
 WITH OTHER 
 
 New Experiments and Difcoverles in the Science, 
 
 m 
 
 ILLUSTRATED BY EXPLANATORY PLATES. 
 
 By the Rev. A. B E N N E T, F. R. S. 
 
 Curate of Wirksworth, Derhyjbire, 
 
 DERBY : 
 
 PRINTF.n BY JOHN DR EWR Y. — M,DCC,I.XXXrx. 
 
Digitized by the Internet Archive 
 in 2011 with funding from 
 Duke University Libraries 
 
 http://www.archive.org/details/newexperimentsonOObenn 
 

 TO THE 
 REVEREND 
 
 Dr. RICHARD KAYE, F. R. S. 6c F. S. A. 
 
 DEAN OF LINCOLN, 
 
 AND 
 
 TRUSTEE 
 
 OF THE 
 
 BRITISH MUSEUM, 
 
 THIS 
 WORK 
 
 IS DEDICATED, 
 BY 
 HIS OBLIGED 
 
 HUMBLE SERVANT 
 
 ABRAHAM BENNET, 
 
nTHE AUTHOR takes this opportunity of ex- 
 
 prejjing his moji Jincere thanks to his fuhfcribers^ 
 
 and efpecially to the following ladies and gentlemen who 
 
 have liberally encouraged his work^ and recommended 
 
 it to their numerous and refpe£iable friends. 
 
 Mr. ADAMS, 
 
 MATHEMATICAL INSTRUMENT MAKER TO HIS MAJXSTY, ANJ> 
 OPTICIAN TO HIS ROYAI. HIGHNESS THE PRINCE OF WALES. 
 
 Sir JOSEPH BANKS, Baronet, F. R. S. 
 
 Mr. G. BLADON. 
 
 Mr. J. CHATTERTON. 
 
 ERASMUS DARWIN, M.D. F.R.S. 
 
 THE REV. THE DEAN OF LINCOLN. 
 
 Mr. FOX, Surgeon. 
 
 PHILIP CELL, Efq. 
 
 Mrs. CELL. 
 
 Captain GELL. 
 
 PHILIP GELL, Efq. Wirkhvortii. 
 
 Rev. Mr. GREVILLE. 
 
 CHARLES HURT, Efq. 
 
 Mr. JACKSON. 
 
 Mifs JONES. 
 
 SAMUEL LANKFORD, Efq. 
 
 Mr. MORE, Sec. S. A. 
 
 THOMAS PERCIVAL, M. D. F. R. S. 
 
 J. H. PIGOT, M. D. 
 
 Rev. JOSEPH PRIESTLY, LL. D. F. R. S. 5:c. 
 
 Mr. JOHN SOUTHERN. 
 
 Mr. WILLIAM STRUTT, Jun. 
 
 JOSIAH WEDGWOOD, Efq. F.R.S.&F./i.S. 
 
 LIST 
 
LIST OF SUBSCRIBERS. 
 
 A. 
 
 Rev. Mr. Achefon. 
 Mr. James Adam. 
 Rev. Dr. Adamchwaite. 
 Dr. Aldrich. 
 Mr. Allen. 
 
 Sir John Anftruther, Bart. 
 Sir Richard Arkwright. 
 Mifs Arnold. 
 Francis Afliby, Efq. 
 Mr. William Atkinfon. 
 Mr. Ifaac Atkinfon. 
 Alexander Aubert,Efq. F. R. S. 
 and F. 8. A. 
 
 B. 
 Mr. A. B. 
 
 Mr. John Bailey. 
 
 Jof. Bainbridgc, Efq. 
 
 Mr. Barr, Surgeon. 
 
 John Barker, Efq. 
 
 Thomas Barker, Efq. 
 
 Mr. Barker. 
 
 Mr. H. Barlow. _ 
 
 John Barnard, Efq. 
 
 Rev. Benj. Barnard. 
 
 Mr. Miles Barnard. 
 
 Rev. T. Barnes, D. D. 
 
 Sir Brooke Boothby, Bart. 
 
 Rev. William Becher, B. D. 
 
 Mrs. Becher. 
 
 Sir Richard Brooke, Bart. 
 
 Lady Brooke. 
 
 Thomas Brooke, Efq. M.P. 
 
 Mrs. Brooke. 
 
 Mifs Bird 
 
 Matthew Boulton, Efq. F.R.S. 
 
 Mr. Matt. Robinfon Boulton. 
 
 Mr. Beard. 
 
 Rev. Theophilus Buckeridge, 
 Principal Surrogate of the 
 Diocefe of Lichfield. 
 
 Rev. Charles Buckeridge. 
 
 Mr. Ch. Broad. 
 
 J. Buxton, Efq, 
 
 Brooke Boothby, Efq. 
 
 Mr. John Birch. 
 
 Mr. Brant. 
 
 John Blackburne, Efq. M. P. 
 
 T. P. Bonnell, Efq. 
 
 Mr. Burman, Surgeon. 
 
 Mr. Brock. 
 
 M,. Brigham. 
 
 Mr. Boot. 
 
 Mr. Johh Beaumont. 
 
 Mr. Jofeph Boden. 
 
 Mr. John Birtles. 
 
 Dr. Blagden, Sec. R. S. 
 
 R. H. A. Bennet, Efq. 
 
 Mr. Blount, Surgeon. 
 
 Mr. Brooke. 
 
 Rev. Thomas Bingham. 
 
 Mr. F. Burton. 
 
 Mr. William Bakewell. 
 
 Mr. Biddulph. 
 
 Mr. H. Brown. 
 
 Rev. Wm. Blackwall, M. A. 
 
 Francis Bradfhaw, Efq. 
 
 Mr. Beaumont, Surgeon. 
 
 Right Hon. Lord G. Cavendifh 
 Henry Cavendifli, Efq. F.R.S. 
 Rt. Hon. Lady Ann Margaret 
 
 Coventry. 
 Rev. Archdeacon Clive. 
 Mrs. Clive. 
 
 Sir Fofter Cunliffe, Bart. 
 Lady Cunliffe. 
 Dr. Crompton. 
 Mr. John Cox. 
 Rev. James Hadley Cox. 
 Mifs Cox. 
 Mifs J. Cox. 
 Mr. William Cantrell. 
 Samuel Crompton, Efq. 
 Mr. Peter Clare. 
 Mr. Samuel Cooper. 
 Thomas Charleton, Efq. 
 Rev, Mr. Chapman. 
 James Chadwick, Efq. 
 Mr. Caldwell. 
 Rev. Benjamin Clay, M. A. 
 Mr. Cropper. 
 
 Rev. 
 
LIST OF SUBSCRIBERS. 
 
 Rev. Mr. Cuffon. 
 Rev. James Cooke. 
 Robert Cheney, Efq. 
 Mr. Clapham. 
 Rev. T. Clarke. 
 Mr. Hollis Clay. 
 Mr. Cockfhutt. 
 Rev. D'Ewes Coke. 
 Mr. Clarke. 
 
 D. 
 
 His Grace the Duke of Devon- 
 
 fhire. 
 Alexander Dalrymple, Efqulre, 
 
 F. R. S. F. S. A. Ac. R. 
 
 Sc. Holm. Soc. 
 C. Dagfon, Efq, 
 Mr. Jennings, Deritend. 
 Mrs. Darwin. 
 Mr. Darwin, Attorney. 
 Mrs. Dawfon. 
 Mr. Thomas Dobbs. 
 Mr. John Dovafton. 
 Rev. Mr. Darwall. 
 Mr. William Dobinfon. 
 C. Davies, Efq. 
 William Dewis, Efq. 
 Mr. Thomas Dicken, Jun, 
 
 E. 
 
 The Hon. & Right Rev. Lord 
 
 BirtiopofEly. 
 George Errington, Efq. 
 T. W. Edge, Efq. • 
 Mrs. Edge. 
 Dr. Eafon. 
 Francis Evans, Efq. 
 Mr. John Eginton. 
 Mr. Francis Eginton. 
 Mr. William Evans. 
 Mr. Elliot. 
 
 His Royal Highnefs Ferdinand 
 Archduke of Aullria, Gover- 
 nor of Milan, &c. 
 
 Sir William Fitzherbert. 
 
 Lady Fitzherbert. 
 
 Mr. Finch. 
 
 Richard French, Efq. 
 
 Samuel Fox, Efq. 
 
 Mr. Edward Fox. 
 
 Mr. William Fox. 
 
 T. Ferriar, M. D. 
 
 Mr. Robinfon Foxley. 
 
 Mr. Field. 
 
 Mr. John Fell, Surgeon. 
 
 Mr. Chrift. Fuller, Attorney. 
 
 Rev. Mr. Freeman. 
 
 Mr. W. Frankland. 
 
 Mifs Fletcher. 
 
 Samuel Frith, Efq. 
 
 G. 
 
 Samuel Galton, Efq. F. R. S. 
 Sam. Galton,jun. Efq. F.R.S. 
 Mr. Goodwin, Surgeon. 
 Mrs. Goodwin. 
 Robert Grimfhavv, Efq. 
 Thomas Gould, Efq. 
 Mr. Thomas Gell. 
 Robert Greaves, Efq. 
 Mrs. E. Grimfhavv. 
 Mr. Gill, Jun. Attorney. 
 Right Hon. Henry Grattan. 
 Rev. Edmund Gregory, M. A. 
 Mrs. Temperance GsJl. 
 Mrs. Gould. 
 Mr. Graham. 
 Mr. F. Geaft. 
 
 Right Hon. Lord Harrington. 
 
 Right Hon. Lady Harrington. 
 
 Sir Henry Harpur, Bart. 
 
 Lady Frances Harpur. 
 
 Henry Harpur, Efq. 
 
 John Hatfell, Efq. 
 
 Mr. James ilatfcll. 
 
 Mr. Hands. 
 
 Mrs. Hands. 
 
 Robert Holden, Efq. 
 
 Mr. Hadley, Surgeon. 
 
 Mr. Haden, Surgeon. 
 
 Francis Hurt, Efq. 
 
 Mann Horsfield, Efq. 
 
 Dr. Hunter. 
 
 Rev. John Le Hunt. 
 
 T. H. Hodges I'^fq. 
 
 Mr. Thomas Henry, F. R. S. 
 
 Mr. Cli. Hey wood. 
 
 Mr. Rich. Hall, Surgeon. 
 
 Mr. Thomas Hadficld. 
 
 Rev. 
 
LIST OF SUBSCRIBERS. 
 
 Rev. Bcnj. Holland. 
 
 Mr. William Harrifon, Surgeon 
 
 Mr. Jof. Hart. 
 
 Mr. John Holmes. 
 
 Rev. George Holcombc. 
 
 Rev. William Hodfon, Fellow 
 
 ofTrin. Coll. Cambridge. 
 Rev. Chrift. Hunter, Fellow 
 
 of Sidney Coll. ^Cambridge. 
 Mr. Horrocks, Attorney. 
 Mrs. Hurt,, fen. 
 Mr. Harding. 
 Mr. John Hunt. 
 Rev. Mr. Hurft. 
 Rev. Mr. Holmes. 
 Mrs. Hopkinfon. 
 Rev. Mr. Hudfon. 
 Mr. Holland. 
 Mr. James Hulme. 
 Mr.JofephHall. 
 Rev. E. Heathcote. 
 Mr. Heberden. 
 C. G. Hudfon, Efq. 
 Rev. C. S. Hope. 
 
 ISc ]. 
 
 Mr. Ince, Attorney. 
 
 William Johnfo^^, Efq. 
 
 Dr. Johnlon. 
 
 R. A. Johnfon, Efq. F.R.S. 
 
 Mrs. Johnfon. 
 
 Mifs Johnfon. 
 
 Mr. P. Johnfon. 
 
 Mr. James Jones. 
 
 Mr, Auguftus Jackfon. 
 
 Nathan Jackfon, Efq. 
 
 K. 
 
 tames Keir, Efq. F. R S. 
 Mr. Thonias Kerfhavv. 
 
 L. 
 
 Chevalier Landriani. 
 Shcrbrooke Lowe, Efq. 
 Mr. John Little. 
 Mr. Penny Lloyd. 
 Robert Lowe, Efq. 
 Mrs. R. Lowe. 
 Mr. Leaper, Attorney. 
 Mr. Locket, Attorney. 
 Edward Leacroft, Efq. 
 
 John Leacroft, Efq. 
 
 Mr. Thomas Lomas. 
 
 Mr. J. A. de Luc. 
 
 John Loyd, of Hofoclunos, 
 
 F. R. S.iF. A. S. 
 Mr. Sampfon Lloyd, Jun. 
 Mils Sarah Longden. 
 Rev. C. Laurence. 
 Mr. Lattufiere. 
 
 M. 
 
 Edward Mundy, Efq. M. P. 
 Right Hon. Lady Middleton. 
 F. N. C. Mundy, Efq. 
 Mrs. Mundy. 
 
 Francis Mundy, Jun. Efq, 
 Maior-General James Murray. 
 Sir William Mufgrave, Bart. 
 Mr, Mofcati, General Direftor 
 
 of the Hofpitals at Milan. 
 William Milnes, Efq. 
 Rev. Mr. Moore. 
 R.ev. John Moore, 
 Mrs. Moore. 
 Rev. Thomas Manlove, 
 Rev, S. Murthwaite. 
 Mr. Macniven. 
 John Mitchel, M. D. 
 ivlr. Richard Marriot. 
 Samuel Martin, Efq. 
 William Middlcmore, Efa. 
 Mr. William Matthews. 
 Mr. William Mott, Dep. Reg.. 
 
 and Proctor. 
 Richard Molefworth, Efquire, 
 
 F. R. S. & F. A. S. 
 Wm. Marfden, Efq, F. R. S. 
 
 and F. A. S. 
 FiCC-Mafon's Lodges, No. 47, 
 
 and No. 189, Macclesfield. 
 Mr. R. Mather. 
 
 N. 
 
 His Grace the Duke of Nor- 
 thumberland. 
 Mr. Nairne, F. R. S. 
 John Need, Efq, 
 Richard Norman, Efq. 
 Mrs. Norman. 
 Robert Newton, Efq. 
 S. W. Nicoll, Efq. 
 
 The 
 
LIST OF SUBSCRIBERS. 
 
 O. 
 
 The Honourable Mr. Oliver. 
 John Ofborne, Eiq. 
 Mr. Oglc> King's Light Dra- 
 goons, 
 
 His Graee the Duke of Port- 
 land. 
 
 Univerfity of Pavia. 
 
 Rev. William Pickering. 
 
 Rev. Edward Pole. 
 
 Mr. George Philips. 
 
 Mr. Polehill, King's Light 
 Dragoons. 
 
 T. B. Parkyns, Efq. 
 
 Mr. Partington. 
 
 Mr. Parkinfon, Surgeon. 
 
 Mr. Pratt. 
 
 Sacheverell Pole, Efq. 
 
 Meflrs. Pcarfon and Rollafon, 
 Printers. 
 
 Mr. Jofeoh Prieftley. 
 
 Richard Pcarfon, M. D. 
 
 Rev. Nathaniel Philips. 
 
 Rev. R. Peryn, M. A. 
 
 Mifs Sutton, 
 Rev. T. Salmon. 
 Mr, Stanley. 
 
 Philofophical Society, Derby. 
 Union Society, Derby. 
 Book Society, Derby. 
 New Society, Nottingham. 
 Jedediah Strutt, Efq. 
 Mr. V/illiam Strutt. 
 Mr. Stevenlon, Surgeon. 
 Mr. James Simpfon, Attorney, 
 E. S. Sitwell, Efq. 
 Robert Shuttleworth, Efq. 
 Rev. Charles Shuttleworth, 
 Mr. John Simpfon. 
 Mr. Samuel Simpfon. 
 William Sherbrooke, Efq. 
 Mifs Coape Sherbrooke. 
 Samuel Smith, Efq. 
 George Smith, Efq. 
 Mr. John Snape. 
 Mifs'Stamford, 
 Caitcl Sherwood, Efq. 
 William Sheldon, Elq. 
 Mr. Robert Small. 
 Mr. William Sherwin. 
 Henry Sykes, Efq. 
 
 e. A. Quift, Efq. 
 
 R. 
 
 Right Hon. Lord Rawdon. 
 Lieutenant-GeneralRainsford. 
 Hayman Rooke, Efq. F. S. A. 
 Mr. Edward Rigby. 
 Mr. H. Richardfon, Jun. 
 George Robinfon, Efq. 
 Mr. Radford, Surgeon. 
 Charles Roe, Efq. 
 
 S. 
 
 Right Hon. Earl of Scarborough 
 Richard Smallbrooke, LL.D. 
 Chancellor of the Diocefe of 
 Lichfield and Coventry- 
 Mrs. Sherbrooke. 
 
 William Tillard, Efq. 
 
 Mrs. Tillard. 
 
 Mifs Tillard. 
 
 Rev. Richard Tillard, 
 
 Mr. JohnThackcr. 
 
 John Topham, Efq. F. R, S. 
 
 John Toplis, Efq. 
 
 Mr. Henry Travis. 
 
 Mr. Tibfon, 
 
 Mr. Toonc. 
 
 Rev. Robert Thorp. 
 
 R^. Vv'. Difney Thorp, M. D. 
 
 Mr. Gervafe Thorp. 
 
 Mr. Twemlow, Surgeon. 
 
 Mr. Taylor, Surgeon. 
 
 Mr. Trevor. 
 
 v&u. 
 
 Mr. Volta, Profeffor of Nat. 
 
 and Exp. Philofophy. 
 Charles Upton, Efq. 
 
 Right 
 
LIST OF SUBSCIBERS. 
 
 W. 
 
 Right Hon. Lord Willoughby 
 
 de Broke. 
 Right Hon. Lady Willoughby 
 
 de Broke. 
 Wm. Wilberforce, Efq. M. P. 
 Mrs. Wilberforce. 
 Mifs Wilberforce. 
 James Watt, Efq. F. R. S. Sec. 
 Mr. James Watt. 
 \Y. Withering, M.D. F.R.S. 
 Sir John Warren, Bart. 
 Rev. W. U. Wray, M. A. 
 Mr. Cecil Bromley Wray. 
 Mifs Webb. 
 Mr. George Whceldon. 
 Rev. Robert Wilmot. 
 Rev. John Ward. 
 Charles White, Efq. 
 Mr. Wynne. 
 Mr. Edmund Wheeldon. 
 Snowden White, M. D. 
 Rev. G. Walker. 
 John Wright, Efq. 
 Thomas Wright, Efq. 
 Captain Wright, King's Light 
 
 Dragoon?, 
 John Wright, Jun. Efq. 
 Mr. Wright. 
 Mrs. H.Wright, 
 
 Mifs Wright. 
 
 Mifs Ann Wright. 
 
 Mifs S. Wright. 
 
 Mifs Lucy Wright. 
 
 Ichabod Wright, Efq. 
 
 George Wyndham, Efq. 
 
 Mifs Wyndham. 
 
 Mr. Ch. Wyat. 
 
 Mr. Th. Willmore, Jun. 
 
 Mr. Robert Weir. 
 
 Mrs. W. Whitaker. 
 
 Mr. John Walker. 
 
 Mr. Thomas Wheeldon. 
 
 Paul Webller, Efq. 
 
 Mr. WoUey, Attorney. 
 
 Mr. Ward, Attorney. 
 
 Rev. Mr. Willey. 
 
 John Wightwick, Efq. 
 
 Dr. Wilfon. 
 
 Mr. William Wilfon. 
 
 Mr. Worral. 
 
 Mr. S. Woodford. 
 
 Mr. Wilfon. 
 
 Mr. George Wilkinfon. 
 
 Mr. John Wilcockfon. 
 
 Mr. Nicholas Yarburgh, 
 Mr. W. Young. 
 
 CONTENTS, 
 
CONTENTS. 
 
 Introdu^ion, containing a flicrt theory of ele£lricity. 
 
 SECTION I. 
 
 Defcription of a gold leaf ehBrometer. 
 
 Slips of tinfoil increafe the fenfbility of the eleSlromeKr, Exp. I . 
 
 sups of tinfoil take off the influence of the cap. Exp. 2. 
 
 SECTION II. 
 
 Poxvdered chalk blo-zvn upon the ele5Irometer. Exp. i to "j 
 
 Some of its varieties explained — Exp. 7 
 
 Experiment to Jheiu the effeii of influential atmofpheres. Exp. 8 
 Chalk projeSled from a brufl?. - _ - . Exp. 9 
 
 The brujh electrified contrary to the cloud of poi-vder. Exp. 10 
 EleQrometer charged poftively by the influence of a nega- 
 tive cloud of po-uoder. - ^ - - Exp. II 
 Chalk and dufl proje8ed fe^veral u-ays. - - Exp. 12^13 
 jill poxvders negative except flour, oatmeal ^ and minium. Exp. 14 
 The eleSlricity ofpoiuders not oiving tofritilion. Exp. 15/5 17 
 Chalk fnoreftrongly eleSlrifcd than flour. - - Exp. 18 
 
 Flame colleils eleflricity in circumflances nvhere it ivould 
 
 not otherivije become fenfihle. - - Exp. 20 to 24 
 PoftiiJe and negative ele^ricity produced by evapmation 
 
 in fc'TJeral nenju methods. - - - Exp. 26/030 
 
 Atmcfpheric eleclricity collelled by a Lantern. - Exp. 31 /o ^2 
 By vjatci' fpouted upiuards. - _ - _ . Exp. 3-^ 
 Heat -Tx-ithcut effiwvium does net diflipate eleSlricity. Exp. 3 } 
 
 Charge of the gold leaf eleiiroTueter too f mall to bt diffl- 
 
 pated by the jharpeft points or edges. - Exp. 36 to 38 
 
 SECTION 111. 
 
 Neiv experiments luith M. Lichtenhurg' s large eleSlrcJ'Loyus. 
 Foivderd chalk projeil<d upon the flgures in various 
 
 'vqaySf - .--...- Exp. \ to zi. 
 A 3 Miniutn 
 
vl. CONTENTS. 
 
 Minium and fulphur mixed are feparately attraSIed by 
 
 pofitive and negative figures. - - - Exp. 22. 
 
 Ramifications and fioades explained - - - Exp. 23/0 27. 
 
 The figures indelibly fixed on fealing ivax. - Exp. 28. 
 
 The figures taken off on paper t leather, callico, cr linen. Exp. 20. 
 
 The figures fixed on porcelain. - - - •• Exp. 30. 
 
 The figures prefernjed by framing the eleSirophorus. - Exp. 3 i . 
 More njoays of varying the figures. - - . Exp.32?5 35. 
 A convenient box for projedingponuders ivithout lofs. Exp. 36. 
 An eledricalpen. ------ Exp. 37. 
 
 To make circles and other figures more conveniently. - Exp. 38. 
 Imitation of Fairy rings _ - - _ Exp. 40. 
 
 SECTION IV. 
 
 Eledricity excited by evaporation. 
 Both fiates of eleSlricity in one experiment. - Exp. i, 
 
 Several metals heated and plunged in vjater. - - Exp. \ to \o. 
 Green vegetables burnt. - - • - Exp. 11. 
 
 Dry a.vood, hay and cinders. ... Exp. 12/0 15. 
 
 Salts, acids, oil and viater. - - - Exp. 16/0 22. 
 
 Various fubfiances dropped upon a hot iron. Exp. 23 to 46. 
 
 Upon Bell metal. - - - . - Exp. 47 /o 4b'. 
 
 A more convenient iron, voith vjhich more fubfiances 
 
 •were tried. - - - - Exp. 49 to 63. 
 
 The afcending vapours examined, - - Exp. 64/070. 
 
 S E C T I O N V. 
 
 Defcripiion of a doubler of eledricity. 
 
 SECTION VI. 
 
 Improvements of the doubler. 
 
 A convenient method of depriving the doubler of its charge. 
 
 The plates of the revolving doubler abforb more eleLiricity 
 
 vohen touched in a parallel pofition. - - Exp. 1^2. 
 XJninfulated approximating plates of different fubfiances 
 
 abforb elei^ricity, . - - Exp. 3 to 6. 
 
 The 
 
CONTENTS. vii. 
 
 The condenfer in its original Ji ate produces a Jlrong fpon- 
 
 taneotts charge of eleSlricity, - - - Exp. 7, 
 
 SECTION VII. 
 
 Experiments on adhejive ele^ricity. 
 By the double contaSi of hardened Jieel and foft iron, Exp. I ?if z. 
 Lead ore and lead, - - - • . Table i. 
 
 Lead and iron ivire, « . - - - Table 2. 
 
 Lead ore and iron 'Wire, ... - Table 3. 
 
 tinfoil and iron 'vjire. . - - - Table 4. 
 
 Zinc and iron --wire, - - - - , Table 5. 
 
 By fingle contaSi of lead ore andzi?ic alternately. - Table 6. 
 Zinc applied to A and B feparately. - - Table 7, 
 
 Lead ore applied to A and B feparately, - - Table 8. 
 
 Suggef ions for impro'ving the accuracy of the revol'ving 
 
 douhler, 
 Adhejive eleSricity explains the excitation of rubbed 
 
 eleilrics, 
 
 SECTION VIII. 
 
 AJhort theory of atmofpheric eleSir icily. 
 
 Defcription of a con'venient apparatus for obfernjing the 
 
 Jiate of atmofpheric eleSlricity in all forts of 
 
 iveather. 
 Convulfve motion of the gold leaf eleiirometer, occajion- 
 
 ed by a thunder cloud. - - - - Obf. 1. 
 Pojitive and negatinje Jiate of Jho^wers. - - Obf. 2 w 5. 
 A thunder cloud <^hich caufed 1 o changes of eleSlricity 
 
 in the fpace of an hour and a half. - - Obf. 6. 
 Clouds and rain, - - - - - Obf. 7/012. 
 
 Serene fky, - - - . - - Obf. 13, 
 
 Clouds and rain. - - . - _ Obf. 14/016. 
 
 Mif. ... - Obf. 17, 
 
 Thundercloud. . - - Obf 18. 
 
 Rain and mijl, - _ - Obf ig to zi, 
 
 Snoiu, mifl and rain. - - Obf. 22 to 25. 
 
 Sleet and rain. - - - Obf. 26 ^ 27. 
 
 A 4 Snoiv 
 
viii. CONTENTS. 
 
 Snoiu. - - - - Obf. 28. 
 
 Miji, fnonx) andjliet. - Obf, 29 /031. 
 
 Wind and hail. - - - Obf. 32 y 33. 
 
 Thunder cloud. - - - Obf. 34. 
 
 Serene iveather- - - . Obf. 35^038. 
 
 Heavy Jhoxver luhoUy pojitivt, - Obf. 39. 
 
 Experiment in dry air, - - - Obf. 40. 
 
 Thundercloud. - - - Obf 41. 
 
 Aurora Eorealis. - - - Obf. 42^43. 
 
 Ten changes of tle^ricity during a Jhoiuer* - Obf. 44. 
 
 A fevere fl}ock from a kite firing. - - Obf 45. 
 
 Aurora Eorealis. - - - Obf. 46. 
 Several clouds pofttive and negative luithout rain, Obf. 48 tff 49. 
 
 Snow, • . - . Obf. 50. 
 
 INTRODUCTION. 
 
L ix. 1 
 
 INTRODUCTION. 
 
 BY the defire of fome of my friends I am 
 induced to prefix a concife theory of Eledri- 
 city, that the reader may more eafily comprehend 
 the intention and ufeof the following experiments. 
 
 I ft. Eledricity is an extremely fubtle fluid, 
 which pervades metals with aftonifhing facility. It 
 alfo pervades water, moift vegetables, animals, 
 and many other fubftances more imperfedly. Thefe 
 fubftances are termed perfed and imperfed: con- 
 ductors. But amber, glafs, filk, oil, dry air, and 
 fome other bodies are impervious to the eledlrical 
 fluid -, and becaufe when rubbed they (hewed figns 
 of eledricity adhering to them, it was once fuppo- 
 fed, that they were the only bodies which contained 
 eledlricity, and were therefore termed eledlrics. 
 
 That fome bodies are conductors and others 
 eledlrics or non-condudlors does not appear to de- 
 pend on their fpecific gravity ; for gold is the beft 
 condu(5lor, and of the greateft fpecific gravity •, and 
 air, which is fo much lefs denfe, does not condu6l-, 
 but charcoal is a good condudor, and lighter than 
 glafs, which is an eledric. It is not improbable 
 but that this property may depend on the chemical 
 affinity of their component parts with the eledlrical 
 fluid. If eledrics are fuppofed to have in their 
 compofition a large quantity of fixed eledricity as 
 Hmeilone contains fixed air, they may be impervi- 
 ous 
 
X. INTRODUCTION. 
 
 ous to any additional quantity of it, becaufe already 
 faturated. 
 
 2dly. Eledricity adheres to the furface of elec- 
 trics much more ftrongly than to the furface of 
 condudtors, and hence when two fuch fubftances 
 are rubbed together, part of the natural quantity of 
 fluid belonging to the conductor adheres to the 
 elecftric. Without this property of electricity its 
 exiftence might never have been difcovered, but 
 firft on rubbing amber and then other eleftrics fome 
 of its effedls were obferved, and after gradual im- 
 provements the prefent electrical machines were 
 conftru6led, and various other difcoveries made. 
 
 3dly. Eledricity is a very elaftic fluid, fo that 
 it may be condenfed or accumulated upon any fub- 
 fl:ance, whofe connection with the earth is cut ofl^ 
 by the interpofltion of an eledlric. This is termed 
 infulation. Electricity, thus accumulated, repels 
 the natural eleCtricity of the furrounding air, dif- 
 poflng it to recede, which is then termed an elec- 
 trical atmofphere, whofe denflty according to the 
 demonftration of the Earl of Stanhope, in his learned 
 principles of eleCtricity is proved to be in the inverfe 
 ratio of the fquare of the diftance. 
 
 An accumulation of eleCtricity which difpofes 
 that of the furrounding air to be repelled is termed 
 a pofitive eleCtrical atmofphere. But if the fame 
 infulated body be deprived of its natural quantity of 
 this fluid, it difpofes the furrounding air to abforb 
 more eleCtricity, and this alfo produces an atmof- 
 phere which is termed negative. 
 
 If 
 
INTRODUCTION. xi. 
 
 If light condudling fubftances as bits of gold leaf 
 be brought within an eledlrical atmofphere, they be- 
 come attracted towards the eledrified body : for the 
 denfity of the electrical atmofphere increafes towards 
 the centre, and the power of its attra(5lion being pro- 
 portionate to its denfity, whatever light conducting 
 fubftances are immerfed in the extreme parts will 
 move towards the centre till they touch the eledri- 
 fied body and receive a part of its eleCtricity. 
 
 When the gold leaf has touched the eleCtrified 
 body, which thus attraifled it, and has received from 
 it a part of its eledricity it becomes repelled ; be- 
 caufe the fuperinduced eledricity will attract a quan- 
 tity of air to form round itfelf another atmofphere, 
 whofe eledricity it tends to repel like the body which 
 was firft eledlritied, and therefore either the light 
 fubftance will move off till it comes into air whofe 
 eledtricity is not repelled by the influence of the firft 
 electrified body, or a double quantity of air muft be 
 attracted into the fame fpace, or lafl:ly the intenfity 
 of the electrical atmofphere between the two bodies 
 muft diminifti, which always happens when the two 
 electrified bodies are immoveable. The fame effeCls 
 will take place whether the atmofphere be pofitive or 
 negative, for every fubftance has as ftrong a tendency 
 to abforb its natural quantity of eleClricity, as it has 
 to emit or diftipate a fuperfluous quantity. This 
 explanation of eleCtrical repulfion eafily applies to the 
 divergency of cork or pith balls or the ftill lighter 
 ihredsof gold leaf ufedin the feveral kinds of fenfible 
 eleClrometers. 
 
 The 
 
xll. . INTRODUCTION. 
 
 The eledrical attradlon and repullion of light 
 fubftances may be illuftrated by cork balls or other 
 light bodies fwimming on water, which adhering 
 round them is raifed above or deprefTed below the 
 common level, and caufes the corks to be attradted to- 
 wards or repelled from each other. When two cork 
 balls are equally moiftened and the adhering water 
 is raifed above the level furface, or when both the 
 corks are dry and the furrounding water is deprefled 
 below t'le level furface, the corks are attracted, which 
 may not feem to agree with the cafe of eledrification, 
 for two equally eledlrified bodies repel each other, 
 but if two light bodies were eledrified in a perfedlly 
 exhaufted glafs, where the air could not interfere, it 
 is probable that they would not repel but attract each 
 other, from the tendency in fluids to unite and form 
 one globular mafs, as two globules of clean quick- 
 silver unite when brought into conta<5b. 
 
 Two light fubftances eledrified in the open air 
 repel each other, becaufe their eledlricity ftrongly 
 attrads the air, which coming between pufhes them 
 afunder, and in like manner the two corks fwimming 
 on water will be repelled, if one of them be made 
 to raife Its furrounding atmofphere of water above 
 the common furface, and the other to deprefs it ; 
 for In this cafe the level furface may be coniidered as 
 a third fubftance flowing in and attracted by each 
 cork to complete its atmofphere, which pufhes the 
 corks afunder. This experiment may be conve- 
 niently tried, by prefUng two bits of thin writing 
 paper upon a round hole about half an inch in dia- 
 meter 
 
INTRODUCTION. x'ni, 
 
 meter, fo as to make the paper concave •, then let the 
 edges be pared, and they will form two fmall paper 
 cups, which are to be placed upon the furface of a 
 bafon of water ; let a little fine fand be put into thefe 
 cups that the edges of the paper may be deprefTed 
 below the level furface of the water, and then the 
 two loaded cups will approach, and at laft come into 
 contad with each other, then let the edge of a 
 moiftened piece of paper be placed in the diredlion 
 of a tangent line between the cups, and they will 
 fuddenly recede to the diftance of feveral inches. 
 
 Every method of condenfing or rarifying the 
 eledrical fluid may be explained by the principle of 
 adhefive attradion : but I fhall here only mention 
 the pradical method of rubbing a flick of fealing 
 wax or rather a glafs tube about five inches long; co- 
 vered with fealing wax upon woollen cloth, for the 
 purpofe of trying the quality of eledricity commu- 
 nicated to an electrometer. It is well known that the 
 fealing wax thus rubbed is excited negatively, that is 
 the natural eleftricity of the fealing wax is left upon 
 the woollen, and its atmofphere being brought fo 
 near as to touch the atmofphere of the eledrometer 
 the gold leaf will either diverge wider or collapfe ; 
 if it diverges more, its eledricity is negative like 
 that of the fealing wax •, but if it coUapfes, it is 
 pofitive. 
 
 4thly. Electricity may be accumulated in a much 
 greater degree upon one fide of a thin eledlric as a 
 plate of glafs or a bottle, if the oppofite fide be con- 
 neded with the earth by means of a condudlor, for 
 
 as 
 
xlv. INTRODUCTION. 
 
 as eledtrlcity is condenfed on one fide of the glafs the 
 natural eledlricity is rarified on the other, and the 
 reftoration of the equilibrium between the two (ides, 
 caufes the effe6b termed an eledrical fhock, and 
 that the fluid may be more fpeedily difFufed over or 
 difcharged from the furface of the glafs it is coated 
 with tinfoil except near the edges. P'luid eledrics 
 may alfo be charged, but becaufe the charge might 
 otherwife foon break throuG;h, the two coatino;s muft 
 be farther diftant from each other, except when the 
 quantity of eledricity is fmall. There is one re- 
 markable difference between the charge of a folid 
 and a fluid eledlric, which is, that the charge prin- 
 cipally adheres to the furface of the folid eledric and 
 not to its coating : but when a plate of air is charged 
 it adheres to the coating : on this conflderation was 
 founded the contrivance of the doubler of eledricity 
 hereafter defcribed. 
 
 That feme quality of accumulated eledlrici'ty 
 fhould a6l through electrics which are impervious to 
 the fluid itfelf, and caufe their natural ele6lricity to 
 expand fo as to produce an eleftrical atmofphere ; or 
 repel the natural electricity on the oppofite fide of 
 an electric in the cafe of charging the leyden bottle, 
 are facts which have long been admired, and though 
 moft of the extraordinary effects of electricity depend 
 on this property, yet I think it has never been very 
 fatisfactorily explained. If the eladicity of fluids in 
 general was clearly underfl:ood, I doubt not but this 
 difficulty would be furmounted, and if the opinions 
 of Des Cartes on this fubjedl were verified by ex- 
 periments 
 
INTRODUCTION. xv. 
 
 periments they might gain credit, notwithftanding 
 the general fallacy of his principles. " Rara cor- 
 pora ilia fint, inter quorum partes multa inter- 
 valla exiftunt, corporibus aliis repleta. Ut cum 
 videmusfpongiam aquavel alioliquore turgentem. 
 Etfi cum aer aut aqua fit rarefafta, non videamus 
 ullos ipforum poros qui ampliores reddantur, nee 
 ullum novum corpus, quod ad illos replendos ac- 
 cedat-, non eft tamen ration! tarn confentaneum, 
 aliquid non Intelligibile effingere, ad eorum rare- 
 factionem verbbtenus explicandam, quam ex hoc 
 quod rarefiant, concludere, in ipfis efse poros, 
 five intervalla quae ampliora redduntur, & novum 
 aliquod corpus accedere, quod ipfa implet -, etfi 
 hoc novum corpus nullo fenfu percipiamus. 
 Nulla enim ratio nos cogit ad credendum, cor- 
 pora omnia quae exiftunt debere fenfus noftros 
 afficere.'* 
 
 Des Cartes Prin. Philos. 
 
 Par. 2. Se6l. 6. 
 
 What Is here faid of the rarefaction of air and 
 water may be applied to the rarefadion of eledlri- 
 city, that is there appears no way of accounting for 
 it but by the fuppofition of another fluid ftrongly 
 adhering to and mixed with it, and which is fuf- 
 ficiently fubtle to pafs thro' glafs. On this hypo- 
 thefis It Is eafy to conceive fuch mixed fluid accu- 
 mulated in a bottle by the adion of an eledrlcal 
 machine, and as the charge goes on and the fluid Is 
 condenfed by being forced into a lefs fpace than It 
 
 would 
 
xvi. INTRODUCTION. 
 
 would otherwife occupy, the fluid which can pafi 
 thro' glafs is forced out and would rarify all the 
 furrounding electricity, by uniting with it, like heat 
 difFufed amongft colder bodies, but being every 
 where infulated, jt is confined, except on the out- 
 fide of the bottle, where becaufe the furface is con- 
 ned ed with the earth its electricity can pafs off. 
 Light is fov conftantly emitted or excited by elec- 
 trical fparks and fo readily pafTes thro' glafs that it 
 might rcafonably be fufpected to be combined with 
 the eledrical fluid and be the caufe of its elafticity, 
 but fome experiments do not feem to favour this 
 fuppofition particularly feci. 2d. Exp. 34. 
 
 By thefe few principles the chief efFeds of elec- 
 tricity as far as they are yet known may be in fome 
 meafure explained ; but it is impoflible to acquire 
 an adequate knowledge of it without an attentive 
 performance of experiments : for altho' I beheve 
 electricity is entirely fubject to the fame laws with 
 every other fabftance, yet becaufe it hath fome qua- 
 lities in a very high degree as fubtilty, elafliicity and 
 adhefive attraction, and others fcarcely at all as 
 gravitation and folidity, it is very difficult without 
 experiments to become imprefled with a juil notion 
 concerning them. 
 
 Since the performance of experiments is fo ne- 
 cefTary to thofe who wifli to acquire a more accurate 
 knowledge of eledricity, I beg leave here to fuggeft 
 that the gold leaf eleftrom'"*'er, may without par- 
 tiality to my own contrivance, be recommended, as 
 the firfl inflirument to be ufed, and the contents of 
 
 the 
 
INTRODUCTION. xviL 
 
 the following fedions may ferve for introduftory 
 leflbns as well as any other. And if the more la- 
 borious and troublefome part of the fcience (hou'd 
 not he approved, there is fufficient fcope for in- 
 fl:ru61ive varieties in the ufe of the electrometer 
 and doubler without more cumberfome machinery, 
 fo that the author hopes, that ladies as well as 
 gentlemen, who have honoured him with their 
 patronage, will here find fome amufement. 
 
 B SECTION 
 
[ i8 ] 
 
 New Experiments, 6c\ 
 
 SECTION I. 
 
 Defcription of a gold leaf eU^rometer. 
 
 p'^^'^^'i^H 1 S inftrument principally confifls of 
 S| x ^ ^^^"o narrow flips of gold leaf fufpended 
 y i? in the middle of a hollow cylindrical 
 
 glals. 
 The foot A plate i, may be made of metal or 
 wood, and about three inches high, that there may 
 be convenient room to handle the inftrument with- 
 out touching the glafs. The cylindrical glafs B 
 in which the gold leaf is fufpended may be about five 
 inches high, and two inches in diameter. The cap 
 C is made of metal, and flat on the top, that the 
 various fubftances whofe eleflricity is to be examined 
 may be conveniently placed upon it. The diameter 
 of the cap is about an inch more than that of the 
 glafs, and its rim D is about an inch broad and hangs 
 parallel to the glafs to keep it clean and dry. Within 
 this is another circular rim about half as broad as 
 the other, made to go over or within the glafs, 
 and is therefore lined or covered with leather, or 
 other foft fubftance, to make it fit clofe, and thus 
 
 the 
 
7^ c4 ' / • 
 
 NEW EXPERIMENTS, &C. I9 
 
 the cap may be eafily taken off to repair any acci- 
 dent happening to the gold leaf. Within this rim 
 and in the centre of the cap a tube is fixed, wherein 
 the peg E is placed. To the peg, which is made 
 round at one end and flat at the other, two flips of 
 gold leaf F are faflened with pafte, gum water or 
 varnifh. 
 
 If gold leaf is ufed it may be fhorter than filver 
 leaf. The gold is much more fenfible, but the filver 
 is eafier to cut and lefs liable to be accidentally torn. 
 I have moftly ufed gold about two inches long, ta- 
 pering to a fine point and faftened to the peg at the 
 broad end. The breadth of the upper end of the 
 gold is about one fifth of an inch, which keeps the 
 flips more cxadlly parallel, and the eledrical repul- 
 fion is more fenfible when the points are narrow, as I 
 have obferved when an accidental very narrow flip 
 hung by the fide of two parallel ones, the narrow flip 
 always moving firft. 
 
 Without the glafs the gold leaf would be fo agita- 
 ted by the leaft motion of the air that it would be 
 entirely ufelefs, and if electricity fhould be commu- 
 nicated to the fides, the gold would be attracted and 
 torn, therefore two pieces of polifhed tinfoil G H 
 are fattened with varnifh on oppofite fides of the in- 
 ternal furface where the gold leaf may be expected to 
 flrike, and are connected with the foot of the elec- 
 trometer. The breadth of the tinfoil at the foot is 
 one fourth of the circumference of the glafs, and it 
 terminates in a point towards the cap, about as high 
 as the peg to which the gold leaf is fattened . It is 
 B 2 broad 
 
20 NEW EXPERIMENTS 
 
 broad at the bottom, becaufe there the points of the 
 gold leaf are mofl: liable to ftrike the glafs, and be- 
 ing made narrow upwards does not prevent the re- 
 pulfion from being eafily obferved. 
 
 Thefe flips of tinfoil, not only carry off fuperflu- 
 ous electricity, but ferve other important purpofes, 
 as will appear from thefe two experiments. 
 
 EXPERIMENT I. 
 
 Upon a fuppofition that the gold leaf was attracted 
 by the tinfoil, I fufpended It in the open air, with- 
 out a glafs, and when electrified I brought two wires 
 near it, and the gold leaves open'd wider, till they 
 touched and collapfed, then upon bringing the wires 
 ftill nearer they again diverged, which proved that 
 the two pieces of tinfoil were ufeful to increafe the 
 fenfibllity of tlie inftrument. 
 
 EXPERIMENT 11. 
 
 I faftened the gold leaf to the infide of an iron mor- 
 tar hanging by a filk firing with the mouth down- 
 wards, and though I communicated to it as much 
 electricity as it would receive, the gold leaf did not 
 diverge till a wire was introduced, which firft caufed 
 the points to open, and then the higher part of the 
 gold, as the wire came nearer to the place where the 
 gold was faftened. This experiment fhews that the 
 tinfoil takes off the influence of the cap which would 
 otherwife dlminifli the repulflon of the gold leaf. 
 
 The upper end of the glafs is covered and lined 
 with fealing wax, at leaft as low as the outermoft rim, 
 
 to 
 
fpcfJ.1 
 
 ON ELECTRICITY. 21 
 
 to render its infulatlon more perfeit, for fealing- 
 wax does not collect moifture from the air fo foon 
 as glafs. In performing this operation, the glafs 
 fhou'd be gradually heated over a candle till it will 
 caufe the wax to flow uniformly over the furface, 
 for if it be covered whilft the glafs is cooler than the 
 wax it will not infulate fo perfectly. The foot may 
 be about three inches and an half in diameter at 
 the bottom, that the inftrument may ftand fufii- 
 ciently firm. 
 
 An electrometer of this kind has been carried 
 from Birmingham to London; another from Wirkf- 
 worth to York, and a third from Wirkfworth to 
 Etruria in a portmanteau on horfeback, yet without 
 injury •, it is therefore eafy to make elecilrometers 
 lefs in every dimenfion, efpecially in diameter, 
 whereby their fenfibility is increafed, and inclofe them 
 in a proper cafe to carry in the pocket, to obferve 
 the atmofpheric eledricity whilft on a journey, or 
 on the top of a mountain. For fome purpofes it 
 may be alfo necelTary to make them larger. In 
 many experiments I have ufed one about five inches 
 in diameter, which fhew'd the changes in the at- 
 mofpheric eledlricity more diftindly than a fmallcr 
 eledrometer whofe gold leaf would fooner ftrike the 
 fides. 
 
 The broad cap of this large elecflrometer was alfo 
 very convenient for placing upon it red hot cruci- 
 bles or veflels of water in experiments on evapora- 
 tion. 
 
 B 3 SECT. 
 
22 NEW EXPERIMENTS 
 
 SECTION 11. 
 
 Experiments on clouds of powders and vapours artifici- 
 ally diffused in the air, and other experiments illujira- 
 ting the principles of ele5lricit)\ andfhewing the great 
 fenjibility of the gold leaf electrometer. 
 
 EXPERIMENT I. 
 
 POWDER'D chalk was put into a pair of bellows 
 and blown upon the cap of the eledrometer, 
 placed at the diftance of about fix inches, which 
 eledrified it politively. See plate 3 fig. 7. 
 
 EXPERIMENT If. 
 
 Powder'd chalk was blown from the bellows to- 
 wards the eleftrometer placed at the diftance of 
 three feet, which caufed the gold leaf to diverge nega- 
 tively. 
 
 EXPERIMENT III. 
 
 The cap of the eleftrometer was moiftened, and 
 the powder'd chalk blown upon it at the diftance of 
 fix inches, which eledrified it negatively, contrary 
 to the dry cap at the fame diftance. 
 
 EXPERIMENT IV. 
 
 Two eledrometers Vv'ere placed with their caps 
 about an inch afunder, the one moift and the other 
 dry, and a ftream of powder from the bellows at the 
 diftance of fix inches was made to pafs between the 
 caps, which eledrified the one poiitively, and the 
 other negatively. EXP, 
 
ON ELECTRICITY. 23 
 
 EXPERIMENT V. 
 
 If a bunch of wire, feathers, or filk, were placed 
 in the bellows, the eledrometer was negatived at 
 the fame diftance which produced a pofitive ftate 
 without them \ alfo blowing gently with the bellows 
 without the iron pipe, (by which means the powder 
 was more widely diffufed in the air) had the fame 
 effect. 
 
 EXPERIMENT VI. 
 
 A red hot ftone was placed upon an infulating 
 fland conneded with the eledrometer, and when 
 powder'd chalk was blown upon It from the bellows 
 within the diftance of fix Inches, it became ftrongly 
 and permanently negative, 
 
 EXPERIMENT VII. 
 
 If the perfon who blows the powder'd chalk into 
 the air from the bellows be infulated by ftanding 
 upon a ftool with glafs feet, and after blowing touch 
 the cap of the eledlrometer, the gold leaf will di- 
 verge pofitively. 
 
 When the bellows produced pofitive eledlrlcity 
 on the dry cap, or negative on the moift one, the 
 cap was permanently eledrlfied : but the negative 
 Hate of the powder, blown at the diftance of three 
 feet, was not communicated •, the gold leaf collapfinsj 
 as the powder paffed away. 
 
 Since the moift cap or hot ftone produce a nega- 
 tive ftate of eledricity within fix inches, the one by 
 detaining the powder, and the other attrading its 
 B 4 eledrlcltv 
 
24 NEW EXPERIMENTS 
 
 elediriclty by means of hot effluvia, it appears that 
 the whole ftream is properly negative : but the 
 powder continues to depoflt eledlricity as it paffes 
 out of the bellows, and.tho' it has loft feme in its 
 way, yet it will elecflrify the cap pofitively whilft 
 thus in the adl of changing its ftate. 
 
 To exemplify this let two metal balls be infulatcd, 
 and let one of them receive a fpark, then bring it 
 near the fecond ball, and it will caufe the natural 
 cle6lricity of this fecond ball to pafs off and ele6lrify 
 any fubftance touching it pofitively, and this fecond 
 ball is left properly negative : but let the firft ball 
 approach nearer, and notwithftanding its negative 
 ftate, the fecond ball will ftill communicate pofttive 
 eledlricity. By this example it is evident that the 
 powder may communicate pofitive eledricity whilft 
 under the influence of fome caufe which renders it 
 negative-, this caufe I fuppofe to be thecontacfl: of air, 
 which has a greater orlefs affinity with the elc'Strical 
 fluid than the powder, and therefore when it is fud- 
 denly project ed into the air, each particle is difpofed 
 by this contaft of air to abforb or emit electricity as 
 it leaves the earth, and in paffing along, the chalk 
 depofits electricity upon the dry cap, whilft the fame 
 powder is acquiring a negative ftate. 
 
 EXPERIMENT VIII. 
 
 When the air is not too dry, or Vv'hen the eleClro- 
 meter has beer, kept in a damp place, let the gold 
 leaf be made to diverge by holding excited fealing 
 wax near it, and let it continue thus diverging about 
 
 half 
 
ON ELECTRICITY. 2^ 
 
 Haifa minute, then fuddenly remove the feallng- 
 wax and the gold leaf will firft collapfc, and then 
 open with a contrary f\ate of eledriclty. This I 
 fuppofed wou'd have explained the pofitive cap 
 above-mentioned: but when a ball of metal was in- 
 fulated in dry weather by a warm tube of glafs 
 cover'd with fealing wax, it became quickly and 
 flrongly pofltive when the chalk was blown upon it 
 within fix inches. 
 
 EXPERIMENT IX. 
 
 A piece of chalk drawn over a brufh {o as to 
 caufe a cloud of powder to pafs over the cap of the 
 eledlrometer, produces a negative repulfion of the 
 gold leaf, but without communicating a negative 
 ftate of electricity. 
 
 EXPERIMENT X. 
 
 Powder'd chalk laid upon a metal plate placed 
 upon the cap and blown off with the mouth or bel- 
 lows, eledlrifies it permanently politive. 
 
 EXPERIMENT XI. 
 
 If a brufli be placed upon the cap, and whilft 
 held with one hand the brufh be rubbed with a 
 piece of chalk till a confiderable cloud of powder be 
 raifed, and then the hand removed, as the cloud 
 difperfcs the gold leaf will diverge pofitively. Or 
 if the cap of the eledirometer be touched by oiie 
 perfon whilft another proiedls ^ cloud of powder'd 
 chalk, the fame efFed will take place. 
 
 In 
 
26 NEW EXPERIMENTS 
 
 In this experiment a pofitive ftate is caufed bv 
 the influence of the negative cloud. 
 
 EXPERIMENT XII. 
 
 Powder'd chalk falling from one plate to another 
 placed upon the eleclrometer, eledtrifies it nega- 
 tively. 
 
 EXPERIMENT XIII. 
 
 A book was chalked upon the edge and fuddenly 
 clapped together, powder'd chalk was projedled from 
 a goofe wing, and the eledlrometer was introduced 
 into the duft raifed from the road by travellers, all 
 which eledrified it negatively : but when duft was 
 ftruck up with a ftick very near the eledrometer it 
 became pofitive, which agrees with exp. i and 2. 
 
 EXPERIMENT XIV. 
 
 Wheat, flour, oat-meal, and minium, produce in 
 every cafe pofitive eledlricity, where chalk and all 
 other powders yet tried are negative ; fuch are red 
 and yellow okre, rozin, coal afties, powder'd cro- 
 cus metallorum, aurum mofaicum, black lead, 
 lamp black, powder'd quick lime, umber, Spanifli 
 brown, powder'd fulphur, flour of fulphur, iron 
 filings, ruft of iron, fand. Alfo powders made 
 from dried decodlion of dyers woods as well as me- 
 tallic calces, on the fuppofition of their fimilarity to 
 flour or minium and other powders not regifteredj 
 but none of thefe laft were pofitive. 
 
 EXP. 
 
ON ELECTRICITY. 2/ 
 
 EXPERIMENT XV. 
 
 The infide of the bellows pipe was moiftened, 
 but this did not alter the eleftricity of the powders 
 blown thro', therefore its excitation does not appear 
 to depend upon fridion in the pipe. 
 
 EXPERIMENT XVI. 
 
 Air alone blown upon the cap does not eledlrify 
 it, nor if blown thro' a hole made in a lump of 
 chalk, whence it is not likely that the eledricity is 
 excited by fridion againft the air. 
 
 EXPERIMENT XVII. 
 
 A lump of chalk was infulated and rubbed upon 
 a brufh faften'd to the cap of the eledrometer, in 
 this cafe both the chalk and brufh were positive, 
 and the afcending cloud of powder negative. Hence 
 probably the excitation of the powder is not occa- 
 fioned by the fridlion of the chalk againft the brufh, 
 fince the ftates of the lump and brufli were not con- 
 trary. 
 
 EXPERIMENT XVIII. 
 
 Equal Meafures and equal weights of powdcr'd 
 chalk and wheat flour were mixed and projected 
 from a brufh, and the eleftricity of the chalk pre- 
 vailed. 
 
 EXPERIMENT XIX. 
 
 Scales of iron were let fall from a plate a confi- 
 derable height above the eledlrometer, which caufed 
 a cloud of duft to arile from the low r plate, this 
 lower plate was therefore eledrified pofitively, con- 
 trary 
 
aS NEW EXPERIMENTS 
 
 trary to the ftate it acquired by fifting the pov/der 
 or letting it fall more gently. 
 
 EXPERIMENT XX. 
 
 A lighted candle placed upon the eledlrometer 
 very much increafes its fcnfibility, and is peculiarly 
 ufeful in colleding atmofpheric eledlricity : but if 
 the communicated eledricity is not conftantly fup- 
 plied, it will alfo foon difTipate its charge in the air. 
 
 EXPERIMENT XXI. 
 
 A fmall tube or glafs cover'd with fealing wax 
 was flightly excited, and the* by the influence of its 
 atmofphere it caufed the gold leaf to diverge con- 
 iiderably wide, it did not communicate its eledri- 
 city even when brought fo near as to touch the cap j 
 but when a candle was placed upon the eleftrome- 
 ter, the electricity was communicated at the diftance 
 of twelve inches or more, and when {Irongly excited 
 it caufed a very fenlible divergency at the diftance 
 of fix feet. 
 
 EXPERIMENT XXII. 
 
 The eledtrometer with its candle was carried into 
 a room juft fwept, and the duft diffufed in the air 
 caufed a very fenfible negative repulfion of the gold 
 leaf. 
 
 EXPERIMENT XXIIL 
 The eleflrometer with its candle was carried thro* 
 a room adjoining to that wherein the eledirical ma- 
 chine had been turned for fome time before, (the 
 
 door 
 
ON ELECTRICITY. 2^ 
 
 door between the Rooms having been left open,) 
 and the air was found very fenfibly eledrified. The 
 fluid being difFufed thro' the air of both rooms- 
 
 EXPERIMENT XXIV. 
 
 Take a quantity of powder'd chalk, and alfo a 
 quantity of wheat flour, and put alternately the 
 chalk and flour into the bellows, and blow the pow- 
 der into the air a few times. It is then eafy for 
 another perfon bringing the eledlrometer with its 
 candle into the room, to difcover Vv'hether the chalk 
 or flour was ufed, the chalk being negative and the 
 flour pofitive. In like manner if chalk and flour be 
 projected on different fides of a room it may be dif- 
 covered where the chalk and where the flour were 
 ufed, or if they were mixed it will fliew which pre- 
 vails. 
 
 EXPERIMENT XXV. 
 No fenfible eleftricity was produced by projecting 
 water, fait, powder'd nitre, or allum, nor by 
 fmoke, flame, or explofions of gunpowder. 
 
 EXPERIMENT XXVI. 
 
 If the fmall end of a tobacco pipe be made red 
 hot, and the pipe be fixed in a cloven fliick, fo that 
 the ftick may be eafily placed in a fmall hole in the 
 cap of the elecftrometer, in fuch a manner that the 
 pipe may be direded towards another eledrometer 
 placed about four inches from the end of the pipe, 
 'jpon putting fome water into the pipe head, the 
 
 fteam 
 
30 NEW EXPERIMENTS 
 
 fteam will fuddenly ifllie out of the fmall end, and 
 eleiftrify the firfl: eledrometer negatively, and the 
 fecond pofitively. 
 
 EXPERIMENT XXVri. 
 Spirit of wine, and ether, were tried with the hot 
 tobacco pipe, and their eledricity did not differ from 
 water, but they required lefs heat. Oil and vitriolic 
 acid produced fmoke which was not electrified. 
 
 EXPERIMENT XXVIII. 
 
 Let a cullender or tin funnel be fufpended by filk, 
 and put fome hot coals in it. Upon throwing wa- 
 ter on the coals the afcending vapour will be found 
 electrified pofitively, and the drops of water falling 
 thro' upon the eledlrometer will be electrified nega- 
 tively : but if a fecond or third quantity of water. 
 be poured thro', the drops will fometimes become 
 pofitive, as will be found more fully tried in another 
 fedion. 
 
 EXPERIMENT XXIX. 
 
 Pofitive eledlricity is produced by blowing with 
 one's mouth thro' a red hot tobacco pipe upon the 
 cap of the eldrometer, by the rarefaction of moifture 
 contained in fuch air : but dry air blown thro' from 
 clean dry bellows does not eleCtrify it. 
 
 EXPERIMENT XXX. 
 
 Vapour of water was drawn into the valve of the 
 bellows and blown upon the eledtrometer thro' the 
 
 iron 
 
ON ELECTRICITY. 3 I 
 
 iroli pipe, yet its pofitlve eleftricity was not de- 
 ftroyed by thus pacing thro' the bellows. 
 
 EXPERIMENT XXXI. 
 
 If a fmali lantern with a candle in it be placed 
 upon the cap of the eledrometer, and expofed to 
 the air in an open place, or not too near high build- 
 ings, or trees, it feldoni fails to render the atmof- 
 phcric eleftriclty very fenfible. 
 
 EXPERIMENT XXXII. 
 The eledroineter was carried into the middle of 
 a field when the weather was clear and frofty, and a 
 fniall lantern placed upon it, caufed the gold leaf 
 to ftand open with pofitive eledlricity about an inch 
 wide, and when carried up a mount about fix feet 
 higher the gold leaf ftruck the fides ; but it gradually 
 coUapfed as it came near trees or houfes. 
 
 EXPERIMENT XXXIII. 
 
 A vefiel of water was placed upon an infulating 
 ftool in the open air, when the weather was dry 
 and clear, then ftanding upon the fiime ftool I 
 fpouted water as high as I cou'd with a fmall fy- 
 ringe about fix times, then upon touching the cap 
 of the eleftrometer with my finger, the gold leaf 
 opened pofitively -, the atmofpheric eledlricity 
 from a higher ftratum of air having charged my 
 body thro' the ftream of water. 
 
 EXP. 
 
32 NEW EXPERIMENTS 
 
 EXPERIMENT XXXIV. 
 Red hot glafs was brought very near the electro- 
 meter and the focus of a concave mirror made to fall 
 upon the cap, neither of which haftened the diffipa- 
 tion of its eledricity. Red hot iron draws it off, 
 but not fo far as flame. 
 
 EXPERIMENT XXXV. 
 
 An iron mortar was placed upon the eledlrometef 
 and red hot cinders were dropped into it whilft elec- 
 trified pofitively or negatively, but this did not di- 
 jTiinifh the divergency of the gold leaf. Bodies of 
 equal furface but different ih mafs, when placed in 
 the fame circuroftances are equally charged with 
 eledlricity, according to the experiments of M. 
 Achard, therefore various fubftances may be intro- 
 duced into the mortar or other hollow vcffel placed 
 upon the cap of the eledrometer, without adding 
 to the quantity of eledrified furface, which may be 
 ufeful in trying various chemico-elecftrical experi- 
 ments. 
 
 EXPERIMENT XXXVI. 
 
 If the ele6lrometer be charged with a fmall quan- 
 tity of electricity, and the fharpeft pointed needle 
 or edge of a razor be brought within the leaft vifible 
 diftance towards the cap, it will not draw off its elec- 
 tricity, but flame draws it off at a confiderable dif- 
 tance. 
 
 This experiment fhews that fhafp points or edges 
 need not be avoided in the conftru6lIon of this in- 
 ftrument, or of the doubler, or atmoipheric appa- 
 ratus 
 
ON ELECTRICITY. 33 
 
 iratus defcribed in the following fedions, and that a 
 flame is better than a pointed wire for the purpofe 
 of collecting atmofpheric electricity. 
 
 EXPERIMENT XXXVII. 
 
 A very light pith ball was put upon the end of 
 a very fmall wire, and the wire was fufpended by a 
 ring to the prime condudor of the electrical ma- 
 chine •, alfo a wire of the fame length, but without 
 any pith ball, was fufpended in a fimilar manner^ 
 and both were repelled by the eleCtricity commu- 
 nicated to the conductor i but the wire with the pith 
 ball defcended firit, which alfo fhews that it is more 
 necelTary to make the electrometer light than to 
 avoid points and edges. 
 
 EXPERIMENT XXXVlII. 
 
 A fmall pin was faften'd upon the end of a ftick 
 of fealing wax and charged with electricity, which 
 was communicated from the pin to a metallic in- 
 fulated conductor, fifteen inches in diameter, and 
 feven feet long, whofe furface was therefore pro- 
 digioufly larger than that of the pin, yet its electri- 
 city caufed a very feniible divergency of the gold 
 leaf. This not only (hews the fenfibility of this 
 electroriieter i but affifts our conception of the 
 amazing divifibility and elafticity of this wonderful 
 fluid, 
 
 C SECTION 
 
 ["A defcription of the gold leaf eleftrcmeter and moft of the 
 above experiments, are printed in the philofophical Tranfadlions 
 for the year 1787.] 
 
34 NEW EXPERIMENTS 
 
 SECTION III. 
 
 Nc-jj experiments ivith M. Llchtenburg's large 
 ele£lrophoru5. 
 
 THE following experiments are intended as 
 improvements on M. Llchtenburg's beauti- 
 ful configurations, firft made on a refinous eledro- 
 phorus by drawing over it the knob of a charged 
 phial, and rendered vifible by fifting powder'd rofin 
 over the plate, which falling fo differently according 
 to the circumflances in which the experiment is 
 made, exhibits the difFuiion of eledricity in a very 
 pleafing manner. 
 
 My firft eledlrophorus was a glafs plate fifteen 
 inches fquare, cover'd on one fide with a thin refi- 
 nous black coating, with tinfoil pafted on the other 
 fide; for if the fide oppofite to the refinous one be 
 not a conductor, the eledlrical fluid will not be eafi- 
 ly difi^ifed over it. Glafs was ufed that the elec- 
 tricity might not be (o liable to pafs thro' the fmall 
 holes and bliftered places which cannot well be avoid- 
 ed if the refinous fubftance be thinly fpread upon 
 wood or metal. 
 
 As powder'd rofin projedled from a brufh is nega- 
 tively eleftrified, there appeared no doubt but that 
 chalk and other powders, which by the fame means 
 are negatively ele6lrified, would anfwer as well or 
 better; fuch powders were therefore tried and found 
 to fucceed remarkably well. 
 
 EXP, 
 
ON ELECTRICITV. 35 
 
 EXPERIMENT I. 
 The plate was fufpended by a loop againft a wall 
 that the grofler part of the powder might fall to the 
 ground, and no more adhere to the plate than Was 
 attracted by the eledricity difFufed thereon. A fmall 
 phial was charged very weakly by one revolution of 
 the eledrical machine, and after its knob had been 
 drawn over the refinous plate, a cloud of chalk was 
 projeded by rubbing the lump upon a brufK near 
 the eledlrified furface of the plate, this produced a 
 plain white line without any ramifications. 
 
 EXPERIMENT II. 
 
 When the phial was charged by three revolutions 
 of the machine, ramifications appeared upon the 
 plate at a confiderable diftance from each other. 
 
 EXPERIMENT III. 
 
 Five or fix revolutions caufed the eledrical fluid 
 to fpread upon the plate in ramifications very near 
 each other. Clofe to each branch a fmall fpace was 
 left uncover'd with powder, forming a kind of 
 fliade to the figure. Beyond this fliade the powder 
 lay fmooth, foftening off externally. 
 
 EXPERIMENT IV. 
 
 "With a very flrong charge the ramifications were 
 clofe and broad, refembling white feathers with a 
 verv broad fhade. 
 
 C a EXP 
 
3^ NEW EXPERIMENTS 
 
 EXPERIMENT V. 
 
 A large jar was charged as full as it wou'd hold 
 and its knob drawn over the refinous plate, the 
 middle of the figure was about an inch broad, and 
 moftly plain and white, the fhades were now more 
 confpicuous than the branches, and dark irregular 
 ftreaks interfecled the diflant white fpace. 
 
 EXPERIMENT VI. 
 
 When a bottle with a large wooden knob in it 
 was highly charged, and its knob carried at the 
 diftance of an inch from the plate in a diredlion acrofs 
 it, the figure produced had no ramifications, but 
 feveral cloudy white ftreaks appeared ; thefe ftreaks 
 vary their figure every time the experiment is tried. 
 
 EXPERIMENT VII. 
 When a figure was made upon the plate by draw- 
 ing with a moift finger, and the moifture touched 
 with the knob of the charged phial, the ramifica- 
 tions darted from the fides of the figure in a per- 
 pendicular direftion ; whereas the ramifications 
 made by Aiding the knob over the plate ifilied from 
 the middle of the figure, floping like the branches 
 of a tree. The reafon of this difference is plainly 
 that in the firft cafe each ramification is made at 
 the fame time, and in the latter the firft branch 
 repels that which is made after it, and thus prevents 
 it from darting perpendicularly. 
 
 EXR 
 
ON ELECTRICITY. 37 
 
 EXPERIMENT VIII. 
 
 A fmall wire was laid upon the plate and an elec- 
 trical fhock made to pafs thro' the wire, which was 
 then thrown off without being touched ; in this cafe, 
 when the chalk was projefled, the ramifications ap- 
 peared very diftindl and long but not fliaded, and 
 their diredtion was perpendicular to the figure. A 
 moderate charge produced longer ramifications than 
 a very flrong one. 
 
 EXPERIMENT IX. 
 
 A circular brafs plate with an infialating handle 
 was placed upon the refinous plate, and a fpark 
 from the charged bottle was communicated to the 
 brafs plate which was then taken off by its infula- 
 ting handle, and chalk projected, which produced 
 a very regular circle of ramifications about four 
 inches long, proceeding from the circumference of 
 the fpace cover'd by the brafs plate, and within the 
 circle were a number of irregular figures fomewhat 
 like ftars. A fhock made to pafs thro* the fame 
 plate generally produced more diftindl ramifications, 
 and fometimes without any ftars within the circle ; 
 and if the brafs plate was drawn along towards the 
 edge of the eledtrophorus whilft touched with the 
 knob of the phial a very beautiful figure was pro- 
 duced. 
 
 EXPERIMENT X. 
 
 The refinous plate was fattened to the top of the 
 
 pillar which fupports and infulates the cuihion of the 
 
 C 3 cle(5lrical 
 
SS NEW EXPERIMENTS 
 
 ele<5lrical machine, and whilft the wheel was turning 
 a brafs knob was drawn over the plate, which pro- 
 duced very large and fine ramifications. A point 
 dravm over, produced a figure very much refem- 
 bllng a white oftrich feather. 
 
 EXPERIMENT XI. 
 
 The plate remaining on the pillar as In the laft 
 experiment, a candle was brought very near the 
 middle and immediately again removed. When 
 chalk was projedted, a circular fpace about twelve 
 inches diameter was cover'd with powder, having a 
 dark fhade round it, beyond which the powder fell 
 more thinly. 
 
 EXPERIMENT XII. 
 
 The plate was faftened to the prime condudlor, 
 and when the candle had been prefented tov/ards the 
 middle as before, the chalk fell moftly on the out- 
 fide of a circle of the fame dimenfion. 
 
 EXPERIMENT XIII. 
 The phial was charged weakly negative and drawn 
 over the plate which produced a plain line, but 
 with chalk it was often black upon a white ground, 
 contrary to the pofitive line. With wheat flower 
 the line was as white as the pofitive one. Projedled 
 chalk being negative, and wheat flower pofitive, 
 they wou'd always be only attraded by thofe 
 figures whofe eledricity Is contrary, but there Is 
 reafon to believe that fome of the projeded powder 
 
 Is 
 
ON ELECTRICITY. 39 
 
 is either not eledrified or pofTefTes a ftate contrary 
 to the rert, and therefore falls into the figure, but 
 the difference of the powders is very confpicuous. 
 
 EXPERIMENT XIV. 
 
 The phial was charged flrongly negative, and 
 drawn over the plate. The figure was not ramifi- 
 ed but confifted of a number ofroundifh fpots, the 
 largeft about the fize of a pea, with fmaller fpots 
 between the large ones, the figure was fhaded, and 
 the fpace beyond cover'd with powder as in the po- 
 fitive experiments. 
 
 EXPERIMENT XV. 
 
 A phial ftrongly and negatively charged was 
 drawn over the plate, and afterwards a pointed wire 
 held in the hand only, was drawn over the fame 
 figure, then chalk was projeded, which produced 
 a beautiful ramified figure in the mid4Ie of the 
 negative one. 
 
 EXPERIMENT XVI. 
 
 A conical tin funnel was placed with its bafe on 
 the middle of the refinous plate, and a negative 
 ftrong charge given by connedling the difcharging 
 rod with the under fide of the plate, then a pofitive 
 charge was given in the fame manner, the funnel 
 was thrown off and chalk projeded, which produ- 
 ced very beautiful ramifications both within and 
 on the outfide of the circle. 
 
 C 4 EXP. 
 
40 NEW EXPERIMENTS 
 
 EXPERIMENT XVU. 
 
 A phial was charged pofitively, and placed with 
 its knob about half an inch diftant from the middle 
 of the plate. Whilft the phial ftood in this fitua- 
 tion challc was proje6led, which adher'd fmoothly 
 to the knob of the phial, and to the furface of the 
 plate for the fpace of about 9 inches diameter, 
 every where cover'd except a very diftindl circular 
 fpot about three inches diftant from the knob, if 
 the chalk was proje6led at feveral intervals, the 
 fucceffive projedlions, did not come up to the edge 
 of the firft circle, but fell round a larger circum- 
 ference and not quite parallel to the firft. A nega- 
 tive charge produced the fame kind of fpot. The 
 caufe of thefe fpots was found to be ele6lricity 
 ftreaming thro' the air from the cork in the neck 
 of the phial, for a wire placed in the cork near that 
 which fupported the knob alter'd the fhape of the 
 ipot. The reafon that it was left entirely without 
 powder tho' occafioned by the communication of 
 eledricity, will appear in a fubfequent experiment. 
 
 EXPERIMENT XVIII. 
 
 A knob of wood about an inch in diameter was 
 placed upon the wire of a phial which was charged 
 highly pofttive, and the knob drawn over the plate 
 fo as to touch the furface, this produced a beautiful 
 figure, the middle of which was fmoothly cover*d 
 with chalk, and the fides finely ramified with 
 ihades, 
 
 EXP. 
 
ON ELECTRICITY. 4I 
 
 EXPERIMENT XIX. 
 
 A brafs knob about three inches In diameter was 
 placed upon the phial inftead of the fmall one, and 
 a ramified figure drawn with It upon the middle of 
 the plate ; then, before chalk was projected, the 
 knob 'with the remaining charge was placed oppofite 
 to the figure at the diftance of about half an Inch. 
 In this cafe the powder fell upon the knob, and on 
 the outfide of the figure, leaving Its ramifications 
 clean and diftind, but entirely without powder. 
 
 EXPERIMENT XX. 
 
 A fmall candle was infulated and its flame placed 
 about an inch diftant from the middle of the refinous 
 plate, then the knob of a pofitively charged phial 
 was fuddenly brought to the flame, and both the 
 flame and phial inftantly taken away again. In this 
 experiment when the chalk was projected a circular 
 fpace about four Inches in diameter was clean and 
 free from powder, the reft of the plate was cover'd, 
 except a great number of fmall circular or elliptical 
 fpots, which fhews that the eleftrical fluid pafTed to 
 the plate in detached balls like feme atmofpheric 
 meteors, or the plate abforbed from the air a con- 
 trary ftate of eledlrlcity, which produced this ap- 
 pearance. 
 
 EXPERIMENT XXI. 
 
 If a pofitive figure be firft drawn and then a ne- 
 gative one acrofs it or v. v. when the powder is 
 projeded it is eafy to diftinguifli which was firfl 
 
 drawn. 
 
42 NEW EXPERIMENTS 
 
 drawn, the fecond appearing to cover the firft, and 
 when the pofitive figure is made laft, the ramifica- 
 tions at the place of jundlioii extend fiirther than the 
 reft and are left without powder. But if both the 
 ftrokes are pofitive or negative the fiirft will appear 
 to cover .the fecond. 
 
 EXPERIMENT XXII. 
 
 If powders of different colours are mixed and 
 proje6led over the figures, fome of the colours will 
 prevail on the middle and fome on the outiide, and 
 efpecially if two figures whofe eledtricity is contrary- 
 are made on the fame plate, and moft of all when 
 both the electrical ftates of the figures and powders 
 are contrary : for example, if minium whofe eledlri- 
 city is flrongly pofitive, and fulphur very flrongly 
 negative be pounded together, and then this mixed 
 powder put into the bellows, and blown upon the 
 contrarily ekdrified figures, the powders feparate 
 and the fulphur falls on the pofitive figure and the 
 minium on the negative. This produces a very 
 pleafing eflPedl. I had often tried the experiment 
 by projeding the powder from a brufli : but the 
 bellows do It much better, which laft method was 
 communicated to me by the Chevalier Landriani, 
 who had (cQii it tried in Italy. 
 
 EXPERIMENT XXIIf. 
 In fome of the above experiments, when the re- 
 finous plate was pofitively eledrified by drawing 
 over it the knob of a charged phial, and chalk pro- 
 
 jeded, 
 
ON ELECTRICITY. 43 
 
 jefted, the middle of the figure was covered with a 
 plain flrealc of powder, or (if the charge was wea- 
 ker) with beautiful white ramifications refembling 
 flowers ', round thefc ramifications there appeared a 
 dark fhade very exadtly defined, whereon no powder 
 fell, and next to this the powder fell fmooth, dimi- 
 nifhing in thicknefs towards the edge of the plate. 
 On the firft view of thefe appearances, I fuppofed 
 that the pofitive eledlricity depofited upon the plate 
 in the middle of the figure had render'd the fliaded 
 part of the fpace negative, and that therefore alter- 
 nate fpaces were pofitive and negative : but upon 
 placing a wire in the cap of my electrometer, and 
 drawing it over the plate in various diredlions, and 
 fometimes covering different parts of the figure 
 whilft others were tried I could never difcover any 
 figns of a negative ftate of eledlricity. The whole 
 plate appeared pofitive, its intenfity diminifliing 
 from the middle of the figure. 
 
 EXPERIMENT XXIV. 
 Not perfedly convinced of the entire pofitive 
 ftate of the electrified plate by examining with the 
 eleftrometer, I cem.ented a wire to the end of a 
 glafs tube covered with fealing wax, in fuch manner- 
 that the two ends extended each way like the points 
 of a pair of compafTes, then taking hold of the 
 glafs tube, I placed one end of the wire in the 
 middle of a pofitive figure, and the other end upon 
 a clean part of the plate, and drew the wire in the 
 diredlion of the figure, keeping the firll point in 
 
 the 
 
44 NEW EXPERIMENTS 
 
 the middle. Upon projedlng chalk where the 
 point had touched the clean part of the plate, fhaded 
 ramifications appeared which plainly /hewed the 
 middle of the figure to be ftrongly pofitive, as 
 might be expeded. 
 
 EXPERIMENT XXV. 
 
 A pofitive figure being drawn as above, the 
 white part in the middle was carefully wiped off 
 with my finger, fo as to difcharge its eleftricity, 
 then the wire was placed with one point in the fhaded 
 fpace and drawn along the figure. Upon projecfb- 
 ing chalk over the clean part of the plate pofitive 
 ramifications were produced as before, but much 
 weaker. 
 
 EXPERIMENT XXVI. 
 
 The white ramifications and fhades were both 
 wiped ojff", and the wire placed near the edge of the 
 fmooth white fpace, and with the other point on the 
 clean part of the plate, and upon projeding chalk 
 there was no figure produced : but if the wire was 
 drawn in the fame manner without wiping off the 
 fhaded part, a white line appeared with very few 
 points like thorns, which fijfiiciently proved that it 
 was weakly pofitive ; and hence it appears that it 
 was the natural eledricity of the plate difpofed to 
 attrad powder by the influence of that which was 
 communicated in the figure, 
 
 EXP, 
 
ON ELECTRICITY. 45 
 
 EXPERIMENT XXVII. 
 
 The white ramifications in the middle of the figure 
 were wiped off and then more chalk projeded upon 
 the fhaded part which caufed the ramified points to 
 extend farther, and by wiping off fl:ill more and 
 projeding chalk again, almoft the whole of the 
 ihaded part was filled, which proves that this lad 
 fpace is left uncover'd, becaufe the ftronger elcdlri- 
 city in the middle of the figure attrads all the pow- 
 der which might otherwife fall in that fpace. And 
 in many other experiments it is found that various 
 parts of the fame plate will be filled with powder or 
 left clean, where the fame ftate of eleftricity, but of 
 different degrees of Intenfity, has been communi- 
 cated, particularly exp. 3, 4, 5, 17, 18, and 19. 
 
 EXPERIMENT XXVIII. 
 
 Glafs plates were cover'd with red or black feal- 
 ing wax, and figures drawn upon the wax, then 
 powder'd fealing wax, or other powders which' 
 wou'd not lofe their colour by heating, were pro- 
 jedled upon a plate of the oppofite colour, and by 
 holding the plates before a fire or over a candle till: 
 the furface was foftened, the figures were indeliblv 
 fixed 
 
 EXPERIMENT XXIX. 
 
 I have tried to take off' the figures upon paper 
 in various ways, and firfb projected lamp black, 
 ivory black, powder'd rotten ftone, vermilion, and 
 many other powders, fometimes mixing them with 
 
 cjun'. 
 
4-6 NEW EXPERIMENTS 
 
 gum arable, and then laying over the plate a paper 
 foftened in water, with or without gum arabic dlf- 
 folved in it, and in fome experiments the figures 
 came off very well, efpecially with vermilion, but 
 moftly failed. I then tried the dry'd extra(5t of 
 dyers woods, and fucceeded very well. And fince 
 feveral of my friends have expreffed their defire to 
 be informed of the procefs, I will defcribe it as 
 minutely as I can. 
 
 To make red figures, take a pound of rafped Brazil 
 wood, put it into a kettle with as much water as 
 will cover it, or rather more ; alfo put in about an 
 ounce of gum arabic and a lump of allum about as 
 big as a large nut, let it boil about two hours, or 
 till the water is ftrongly coloured ; ftrain off the 
 extradt into a broad difh, and fet it in an iron oven, 
 where it is to remain till all the water be evaporated, 
 which with me was effecfted in about 12 hours-, but 
 this depends on the heat of the oven, which ihou'd 
 not be fo hot as to endanger its burning. Some- 
 times I have boiled the {trained extract till it was 
 confiderably infpiffated before it was placed in the 
 oven, that it might be fooner dry. 
 
 When it is quite dry but not burnt, fcrape it 
 out of the difh and grind it in a mortar till it be 
 finely pulverized. In doing this it is proper to co- 
 ver the mortar with a cloth having a hole thro' to 
 prevent the powder from flying away and offending 
 the nofe, and alfo to do it out of doors if the wea- 
 ther be dry and calm, that the air may carry away 
 the powder necefTarily efcaping, and which other- 
 wife 
 
ON ELECTRICITY. 47 
 
 wife is very difagreeable. When ground fine let it 
 he fifted thro' muilin or a fine hair iieve, returning 
 the coarfer part into the mortar to be ground again. 
 When the grinding and iifting are finifhed the pow- 
 der is ready for ufe. The refinous plate I have 
 moftly ufed was compofed of five pounds of rofin, 
 half a pound of bees wax, and two ounces of lamp- 
 black, melted together and poured upon a board 
 fixteen inches fquare, with ribs upon the edges at 
 leall; half an inch high, to confine the compofition 
 whilft fluid, thus the refinous plate was half an inch 
 thick, which is better than a thinner plate, the 
 figures being more difl:in6t. After the compofition 
 is cold, it will be found covered with fmall blift:ers, 
 which may be taken out by holding the plate before 
 the fire, till the furface be melted, then let it cool 
 again, and upon holding it a fecond time to the 
 fire, more blifters will appear -, but by thus repeat- 
 edly heating and cooling the furface, it will at laft 
 become perfedly fmooth. Some plates were made 
 fmaller and the refinous compofition confined to the 
 form of an ellipfis, a circle or efcutcheon, by a rim 
 of tin half an inch broad, and fixed upon a board. 
 
 The next thing to be done is to prepare the pa- 
 per, which is to be foften'd in water, either by lay- 
 ing the pieces upon each other in a vefiel of cold 
 water, or firft pouring a little hot water upon the 
 bottom of a large difh, then laying upon it a piece 
 of paper, fo that one edge of the paper may lie over 
 the edge of the difh, to remain dry, that it may 
 afterwards be more conveniently taken up. Then 
 
 pour 
 
4^ NEW EXPERIMENTS 
 
 pour mof e hot water upon its upper furface. Upoii 
 this place another piece in the. fame manner, again, 
 pouring on more water, and thus proceed tiU all the 
 pieces are laid in. By uiing hot water the paper 
 will be more foftened in a few minutes than if it 
 remains in cold water a whole day. 
 
 When the figures are to be made the refinous 
 plate muft lie horizontally whilfl the eledricity is 
 communicated, if the experiment requires any thing 
 to be placed upon the plate : but it is convenient 
 afterwards to hang it up in a vertical pofition whilft 
 the powder is projeded, left too much powder 
 fhould fall where it is not required. 
 
 A little of the powder may be taken between a 
 finger and thumb, and projeded by drawing it over 
 a brufti, or which is better, a quantity of powder 
 may be put into the bellows and blown towards the 
 plate. When the figure is fufficiently covered with 
 powder^ let the plate be again laid horizontally upon 
 a table, then take one of the foftened papers out of 
 the water by its dry edge, and lay it carefully be- 
 tween the leaves of a book, prefiing the book to- 
 gether, and let it lie in this fituation about half a 
 minute. Then remove the paper to a dry place in 
 the book, and prefs it again about the fame time, 
 which will generally be fufficient to take off the fu- 
 perfluous moifture. Then take up the paper by 
 the two corners of its dry edge, and place the wet 
 edge a little beyond the figure on the refinous plate 
 lowering the reft of the piece gradually till it covers 
 the figure without Aiding, then lay over it a piece of 
 
 clean 
 
ON ELECTRICITY. 49 
 
 clean dry paper, and prefs it gently, let it remain 
 a fhort time, and then rub it clofer to the plate 
 with a cloth, or which is better, prefs it down by 
 means of a wooden roller cover'd with cloth, taking 
 care that the paper be not moved from its firfl 
 pofition. When the paper is fufficiently prefled 
 let it be taken up by its dry edge, and laid upon 
 the furface of a vefTel of water with the printed fide 
 downwards, by this means the fuperfluous powder 
 will fmk in the water, and the figure will not be fo 
 liable afterwards to fpread in the paper. After the 
 paper has remain'd on the water during a few 
 minutes, take it up and place it between the leaves 
 of a book, removing it frequently to a dry place. 
 If it be defired that the paper fhou'd be fpeedily 
 dry, let the book-leaves in which it is to be placed, 
 be previoufly warmed, and by removing it to feve- 
 ral places, it Vv'ill be dry much fooner than by hold- 
 ing it near a fire, and without drawing the paper 
 crooked. By the above procefs it is obvious that 
 leather, callico, or linen, as well as paper, may be 
 printed with thefe figures, and the eiFeds of the 
 difFufion of eleftricity upon a refinous plate be ex- 
 hibited to thofe who have not leifure or inclination 
 to perform the experiments. 
 
 The atmofpheric eledricity with all its variation? 
 of intenfity, and changes from pofitive to negative 
 are marked on a refinous plate by an ingenious 
 machine of the Chevalier Landriani, which moves 
 bv a clock, and the figures made on the plate du- 
 ring his abfence will become vifible when powder is 
 
 D pro 
 
50 NEW EXPERIMENTS 
 
 projedled. Thefe figures may therefore be taken 
 off by this procefs, and the ftate of a day's elec- 
 tricity in Italy be tranfmitted to England. 
 
 EXPERIMENT XXX. 
 
 Mr. Wedgwood propofed to fix the figures by 
 projefting fine powder'd enamel, after the eledlricity 
 was diffufed upon porcelain, and then to bake the 
 plate or vefTel (thus ornamented) in the ufual way. 
 This experiment was tried at his houfe, and the 
 figures were very well fixed •, but the weather being 
 then unfavourable, they were not fo beautiful as 
 might be expedled. I have fince made the figures 
 with more fuccefs, but had not the opportunity of 
 fixing them. 
 
 In this way the ramifications and fhades may be 
 indelibly fixed and prcferved, without any diminu- 
 tion of their beauty. 
 
 EXPERIMENT XXXI. 
 Another way of preferving the figures is to make 
 a refinous plate of a proper fhape to be framed and 
 covered with glafs. After the figure is made and 
 the powder proje^Sted, it is necefiary to hold the 
 plate over a veffel of hot water, that by means of 
 the fteam its eledlricity may be gradually difcharg- 
 ed, for if it be covered immediately, the powder 
 will fly ofi"' to the glafs. In one experiment I paint- 
 ed a glafs black on one fide, then cover'd the 
 painted fide with brafs leaf, and after heating it in 
 the funlliine till all the moifture was expelled, I 
 
 made 
 
ON ELECTRICITY. 5I 
 
 made the figures upon the uncoated furface, cover'd 
 it with another glafs; and placed it in a frame. 
 When glafs is made very dry the figures will be as 
 diftind: and beautiful as thofe made upon a refinous 
 plate •, but it is neceffary to perform the experiment 
 in dry weather, and to take care that the glafs and 
 knob of the bottle, with which the figures are drawn, 
 be fufficiently and equally heated, for if the knob 
 be colder than the plate, moiilure will be condenfcd 
 and fpoil the figure. In trying experiments with a 
 glafs plate, I obferved that it was very difficult to 
 deprive it of the ele<51:ricity laft communicated. I 
 rubbed the furface with wet cloths, then rubbed 
 water with my fingers upon the eleftrified parts, then 
 dipped the plate in water, and after that held it 
 over the flame of a candle, yet found that all thefe 
 methods were infufficient, the figures might ftill be 
 feen when the glafs was dry, and chalk again pro- 
 jeifled. I then rubbed the glafs with tallow, and 
 cleaned it off with powder'd chalk, which fucceeded 
 better. 
 
 EXPERIMENT XXXII. 
 
 I placed the above defcribed glafs plate in the 
 funfhine where it was kept hot, and dropped a little 
 oil upon the middle, and upon touching the oil 
 with a pofitively charged bottle, it flowed in very 
 fine ramifications. I then touched another drop of 
 oil with a negative bottle, which alfo caufed it to 
 flow in ramifications, which I cou'd not perceive to 
 D ?. differ 
 
52 NEW EXPERIMENTS 
 
 differ from the pofitlve ones, except that they did 
 not extend quite fo far. 
 
 EXPERIMENT XXXIII. 
 
 I rubbed a circular fpace in the middle of the 
 glafs plate with water, and touched it with a charg- 
 ed bottle, then projecfted chalk which cover'd the 
 moift fpace with a plain fmooth coating of chalk, 
 I then dried it over the flame of a candle, which 
 alfo difcharged its eledricify. On the middle of 
 this white fpace I dropped fome oil, and upon 
 touching it with the charged bottle it fhew'd its 
 fpreading ramifications more plainly than in the 
 laft experiment. Alfo this plain white fpace being 
 touched with a pofitive bottle, (by chalk thrown off 
 the furface^ fhews ramifications more diftindly 
 filled with branches than thofe made upon clean 
 glafs or refin. 
 
 EXPERIMENT XXXIV. 
 
 The furface of a refinous plate was melted and 
 powder'd rofin fifted upon it fo as to make it very 
 rough, this caufed the figures to fpread lefs than 
 upon a fmooth plate, fo that the points of the rami- 
 fications came very near the edge without ftriking 
 off. 
 
 EXPERIMENT XXXV. 
 
 A pofitive figure was drawn upon a refinous plate 
 and chalk projected confiderably longer than ufual, 
 and then on examining the figure there appeared 
 
 fmall 
 
ON ELECTRICITY. S3 
 
 Tmall ramified vegetations like thofe produced upon 
 camphire by M. Mofcati. Alfo negative figures 
 with flour produced the fame. 
 
 EXPERIMENT XXXVI. 
 The powders made from the deco6tion of woods 
 defcribed in exp. 29. are very troublefome when 
 projeded in the open air, and a confiderable quan- 
 tity is loft in every experiment. I therefore con- 
 trived to projedt the powder by means of a circular 
 brufli inclofed in a box. Its lid A. plate 3d. fig. i. 
 is fixteen inches fquare, with edges about an inch 
 and a half deep. The refinous compofition is 
 poured within thefe edges of the lid to the depth of 
 half an inch. The fides of the box as far as the 
 perpendicular part at B. are fix inches deep ; the 
 Hoping boards at C. ten inches. The circular box 
 D. in which the circular brufh is inclofed is fix 
 inches diameter, and three inches thick. A wire or 
 fmall glafs tube is put thro' the circular box at E. 
 that the hairs of the brufli when turned round by 
 the handle F. may flirt againft it and projedl the 
 powder thro' an opening at C. and difFufe it into 
 the air contained within the box, and thus the 
 figures made on the refinous plate within the lid 
 will attract the fineft part of the powder, or that 
 which is moft ftrongly eledlrified with the contrary 
 fl:ate to that of the figure, and the reft will fall down 
 again. If the box contains too little powder it 
 will be neceflary to lean it on one fide, and if there 
 be a large qiantity, the brufli muft be turned flowly 
 left it fliou'd throw up too much. Smaller refinous 
 D 3 plates 
 
54 NEW EXPERIMENTS 
 
 plates may be fupported within the box by bars of 
 wood placed acrofs, and cover'd over with the lid 
 whilft the powder is projedled. 
 
 EXPERIMENT XXXVII. 
 
 That I might more conveniently draw a variety 
 of figures as well as try the effed:s of a very fmall 
 Leyden bottle, I made an eledlrical pen, by filver- 
 ing the infide and gilding the outfide of large ther- 
 mometer tubes, from three to eight inches long,, 
 with and without bulbs, covering the ends with 
 fealing wax. In one end was fixed a blunt needle 
 conne6led with the internal metallic furface. Some 
 were coated on the outfide with tin foil, and a wire 
 ferved for the internal coating. Whilil: drawing 
 with them, a charged bottle ftands ready to fupply 
 eledtricity by touching its knob with the point of 
 the needle. Small or large knobs, camel hair pen- 
 cils, thiftle down, and other fubftances occafionally 
 fixed on the point, produce different effecfts, and 
 with the fmalleft pen lines may be drawn as fine as 
 can be made with ink. 
 
 EXPERIMENT XXXVIII. 
 
 For the purpofe of making circles, fpiral lines, 
 volutes, &c. an iron pin is fixed to the conducing 
 fide of the lid of the projeding box at G. plate 3 
 fip-, I ; and when eleftricity is to be communicated 
 to the refinous furface, the pin is placed in a hole 
 made in the table, and the plate whirled round, 
 whilft it is touched with the knob of a charged 
 
 bottle, 
 
ON ELECTRICITY. 55 
 
 bottle, or pen defcribed above, fo as to produce 
 the required figure. 
 
 EXPERIMENT XXXIX. 
 
 The figure nientioned at the end of exp. 9th, 
 made by drawing the brafs plate towards the edge 
 of the eleftrophorus, by its infulating handle whilft 
 the plate was touched by the knob of a charged 
 bottle, fomewhat refembles the pi6lure of a comet ; 
 but in the tail I frequently obferved that a circular 
 or elliptical fpace was left without powder, which 
 may rcafonably be attributed to the abforption of a 
 contrary ftate of ele6tricity from the air, which 
 weakens the intenfity of the charge diffufed in that 
 fpace; fee plate 3, fig. 6. An electrified cloud or 
 ftratum of air emits or abforbs balls of eledrical 
 fire called meteors or falling ftars, to which this 
 experiment may bear fome refemblance. 
 
 EXPERIMENT XL. 
 
 A circular plate of wood 1 2 inches in diameter 
 was covered with tin-foil, and furniflied with an 
 infulating handle, this plate had alfo three feet of 
 glafs about an inch long, cover'd with fealing wax. 
 A refinous plate half an inch thick and of lefs dia- 
 meter than the wooden plate, Vv'as laid upon a table, 
 and the wooden plate placed over it, its feet {land- 
 ing upon the table on the outfide of the refinous 
 plate, fo that the furface of the wooden plate ftood 
 about half an inch higher than the furface of the 
 refinous ylite. The knob of a charged bottle was 
 D 4 applied 
 
50 NEW EXPERIMENTS 
 
 applied to the wooden plate which was then remov- 
 ed. Upon projeding powder the furface of the 
 refinous plate was covered with circular elliptical 
 and irregular fpots and rings. If the charge was 
 weak there appeared only fmall round fpots, but a 
 ftrong charge produced rings broader or narrower 
 according to the Hate of the air and ftrength of the 
 charge. After touching the wooden plate with a 
 pofitive bottle, I fometimes removed the plate a 
 little from its firft pofition, and then touched it 
 with a negative bottle, and inftead of a fingle pow- 
 der, the mixture of minium and fulphur were blown 
 upon the plate, as in exp. 22, which diftinguifhed 
 the pofitive and negative rings by the yellow and 
 red colours. 
 
 Upon examining thefe rings by the method def- 
 cribed in exp. 24, it appeared that the whole fpace 
 included within the rings was covered with eledlri- 
 city •, and yet the powder was only attraded by the 
 edges of the fpace, probably becaufe the intenfity 
 of the middle is diminifhed by the equally furround- 
 ing repulfion of the ildes. 
 
 The circles of green grafs called fairy rings are 
 with great probability attributed to the efFeds of 
 lightning. See Dr. Prieftley's Hift. of Eledricity, 
 vol. 2. page 274, of which this experiment may be 
 efteemed a tolerable artificial imitation. 
 
 SECT. 
 
ON ELECTRICITY. 57 
 
 SECTION IV. 
 
 Experiments in which ele5iricity is condenfed or rarified 
 by the evaporation of water from various fuhjlances. 
 
 IN a treatife on eledlricity by M. I'AbbeHauy, 
 I find that fince M. Volta's difcovery of eledri- 
 city produced by evaporation of water from hot 
 coals, MefTrs. Lavoifier and De la Place have re- 
 marked, that bodies paffing from a folid or fluid 
 ftate into vapour, give unequivocal figns of pofitive 
 or negative eledricity. A large veiTel containing 
 a quantity of iron filings was infulated and conned:- 
 ed with M. Volta's condenfer. Three parts of 
 water and one of vitriolic acid were poured upon the 
 filings, which caufed a brifk effervefcence, and a 
 rapid difcharge of inflammable air, and in a few 
 minutes the condenfer became (o firongly charged 
 that it gave a very fenfible fpark, and by the eledlro- 
 meter it was found to be negative. The produc- 
 tion of fixed and nitrous airs had the fame efFeil. 
 Alfo chafing difhes infulated and filled with lighted 
 coal produced very clear figns of negative eleftri- 
 city after the combuftion of the coal. It appears 
 that in thefe experiments, the fubftances evaporated 
 carry away from the vefiels with which they are in 
 contadl, a part of their natural eledricity. But 
 when water was poured upon red hot iron pans the 
 
 elcc- 
 
58 NEW EXPERIMENTS 
 
 elecflricity was no more negative as in the former 
 experiments, but decidedly politive. Thefe expe- 
 riments were communicated to the academy of 
 fciences in the year 1781. 
 
 M. de SaufTure has alfo tried many experiments 
 of this kind by plunging hot iron and other metals 
 in water, and pouring water into crucibles of iron, 
 brafs, copper, filver or porcelain. Sometimes he 
 ufed diftilled water, alfo fpirit of wine and ether, 
 and in thefe experiments the electricity was fome- 
 times politive, fometimes negative, and fometimes 
 neither. 
 
 M. de Sauflure thinks that when the operation 
 which converts the water into vapour, at the fame 
 time decompofes it, or the body with which it is in 
 contad, it produces a new quantity of the eledrical 
 matter, and that the veiTel ufed in the operation be- 
 comes pofitive, negative, or neither, according as 
 the fluid produced is fuperior, inferior, or equal to 
 that which is taken from the veflel by evaporation. 
 An account of thefe curious experiments is con- 
 tained in the fecond volume of M. de SaufTure's tra- 
 vels over the Alps, page 227. 
 
 The gold leaf eleftrometer being well adapted to 
 the performance of experiments of this kind, I was 
 induced to repeat fome of them with variations in 
 hopes of new appearances. And fince almoft every 
 fubftance in the whole chemical nomenclature may 
 thus be fubjecfted to the adion of fire, and its 
 affinity with eledricity in a ftate of vapour exami- 
 ned. 
 
ON ELECTRICITY. 59 
 
 ned, new fads may yet arife which will produce new 
 theories, therefore the following experiments are 
 placed ill the order they were tried without regard 
 to fyftem. 
 
 EXPERIMENT I. 
 
 A bafon of tinned iron about fix inches wide at 
 the bottom, and eight inches at the top, was placed 
 upon the cap of a gold leaf ele(5lrometer. The 
 bottom of the bafon was cover'd with water about an 
 inch deep. An iron chifTel was heated red hot, and 
 dropped into the water, one end being immerfed 
 and the other refting on the edge of the veffel. The 
 gold leaf gradually open'd about an inch negatively, 
 then clofed and open'd pofitively, remaining pofi- 
 tive to the end of the experiment. See plate 5, 
 %• 5. 
 
 EXPERIMENT II. 
 
 The chifiel was heated more than in the laft ex- 
 periment, and the gold leaf ftruck the fides of the 
 cle6lrometer fix times negatively, then it changed 
 and flood at half an inch pofitive to the end. 
 
 EXPERIMENT III. 
 
 The chifiel was again made very hot and it caufed 
 the gold leaf to fi:rike often negatively, after which, 
 it clofed, but never open'd pofitively. 
 
 EXP. 
 
6o NEW EXPERIMENTS 
 
 EXPERIMENT IV. 
 
 The chiflel was heated very much by blowing the 
 fire, and it caufed the gold leaf to ftrike fourteen 
 times negatively but no pofitive eledrlcity appear- 
 ed, this was repeated above twenty times without 
 any produdion of pofitive eledlricity. 
 
 EXPERIMENT V. 
 
 Upon obferving that the chifl"el was much calcin- 
 ed upon its furface, by being fo frequently heated 
 in the above experiment, I rubbed oiF the calx, 
 and heated it again, and found that now it produ- 
 ced firft negative and then pofitive eledtricity, as 
 before ; whence it appeared that its produdion of 
 pofitive electricity depended upon the metallic fliate 
 of the iron. 
 
 EXPERIMENT VI. 
 
 A large bar of copper and a piece of brais were 
 heated red hot and plunged in the water, which alfo 
 produced firft negative and then pofitive eledlricity. 
 
 EXPERIMENT VII. 
 
 Melted lead was dropped into water contained in 
 the bafon as above, which gradually opened the 
 gold leaf pofitively. 
 
 EXPERIMENT VIII. 
 
 Melted lead being dropped into a deep narrow 
 vefl!el almoft full of water did not eledlrify it, fince 
 
 it 
 
ON ELECTRICITY. 6t 
 
 it emitted no vapour, it is therefore not the mere 
 decompofition of the metal but the formation of a 
 certain kind of vapour which excites electricity. 
 
 EXPERIMENT IX. 
 
 ' BoiHng Mercury was dropped from an earthen 
 crucible into a fmall quantity of water in a porcelain 
 cup ftanding upon the cap of the eledlrometer which 
 caufed the gold leaf to open pofitively. 
 
 EXPERIMENT X. 
 
 Several thin pieces of bell metal were heated red 
 hot and dropped into water, which caufed a nega- 
 tive repulfion only. 
 
 EXPERIMENT XI. 
 
 An earthen unglazed flower pot was half filled 
 with red hot cinders, then the other half was filled 
 with chopped grafs, which caufed the gold leaf to 
 open with pofitive elecflricity, and to continue ftrik- 
 ing the fides a confiderable time. In the fame 
 manner were tried cabbage leaves, lettuces, turnip 
 tops and roots, and chick weed, with the fame re- 
 fults. 
 
 EXPERIMENT XII. 
 
 Turnings of dry afh wood were thrown upon the 
 hot cinders as above, which fmoked much without 
 caufing any repulfion of the gold leaf till water was 
 added, which caufed a fl:rong pofitive ^ledlricity. 
 
 EXP. 
 
62 NEW EXPERIMENTS 
 
 EXPERIMENT XIII. 
 
 Dry hay was burnt In the flower pot, as above, 
 which produced no eledlriclty till water was added, 
 and then it became ftrongly pofitive. 
 
 EXPERIMENT XIV. 
 
 The flower pot wis placed upon the elecflrometer 
 with red hot cinders alone, and water was dropped 
 into the middle, which open'd the gold leaf nega- 
 tively; then more water open'd it pofitively. The 
 cinders were renewed, and water dropped in the 
 middle open'd the gold leaf negatively, then drop- 
 ped near the flde open'd it pofitively, again in the 
 middle negatively. 
 
 EXPERIMENT XV. 
 
 Since the cinders became both pofitive and nega- 
 tive with water only, I repeated the above experi- 
 ments on green and dry vegetables with a red hot 
 earthen crucible, but without any difl^erence in the 
 refult. A fquare piece of brick was firft placed upon 
 the eledtrometer, to prevent the heat from injuring 
 it in this and all the fubfequent experiments, in 
 which red hot bodies were to be placed upon it. 
 
 EXPERIMENT XVI. 
 
 A fpoonful of fait was thrown into the red hot 
 crucible, which open'd the gold leaf negatively ; a 
 fecond quantity was thrown in, and it became po- 
 fitive. 
 
 EXP. 
 
ON ELECTRICITY. 63 
 
 EXPERIMENT XVII. 
 
 The crucible being again heated two fpoonfuls of 
 fait were thrown in, which open'd the gold leaf po- 
 fitively i then water was dropped into the middle 
 of the fait, which changed its eledricity to negative; 
 then more water dropped near the fide of the cruci- 
 ble open'd the gold leaf pofitively ; then again in 
 the middle negatively. 
 
 EXPERIMENT XVIII. 
 
 Salt and water were mixed and dropped into the 
 red hot crucible, which caufed a ftrong negative re- 
 pulfion ; then after the water was evaporated more 
 was dropped in the middle, which renewed the ne- 
 gative repulfion till the water was dropped near the 
 fide, when it became pofitive i this change from 
 poiitive to negative was often repeated. 
 
 EXPERIMENT XIX. 
 
 A fmall quantity of fait was thrown into the red 
 hot crucible, which caufed the gold leaf to open ne- 
 gatively •, then the fait remained till it was burnt 
 black, and water being added caufed a ftrong pofi- 
 tive repulfion. 
 
 EXPERIMENT XX. 
 
 The vitriolic and nitrous acids were feverally 
 dropped upon red hot bricks, which open'd the 
 gold leaf pofitively. The bricks were tried before 
 and after the experiments with water, which caufed 
 a negative repulfion. 
 
 EXP. 
 
64 NEW EXPERIMENTS 
 
 EXPERIMENT XXI. 
 A large red hot cinder was placed upon the elec- 
 trometer, and olive oil dropped upon it, producing 
 a copious fmoke, but no elecftricity, then water was 
 added, which open'd the gold leaf negatively. 
 
 EXPERIMENT XXII. 
 Olive oil and water were fhook together in a phial, 
 and both poured upon a red hot piece of caft iron 
 about an inch thick, 4 inches broad, and 5 inches 
 long, which open'd the gold leaf ftrongly negative. 
 
 EXPERIMENT XXIII. 
 Vitriolic and nitrous acid were dropped upon 
 the caft iron, which open'd the gold leaf pofitively. 
 
 EXPERIMENT XXIV. 
 Dry hay was placed upon the caft iron, and 
 prefled down by a ftone placed upon it till it was 
 burnt black, then water was added, which open'd 
 the gold leaf pofitively. The hay was then bruftied 
 oft", and more water dropped upon the iron, which 
 caufed the gold leaf to open pofitively, till the fur- 
 face was well cleaned and heated again, when it 
 produced negative. 
 
 EXPERIMENT XXV. 
 An heap of wheat flour was placed upon the hot 
 iron, which fmoked without any eledlriclty, till 
 water was added, which open'd the gold leaf pofi- 
 tively. 
 
 EXP. 
 
OM ELECTRICITY. 65 
 
 EXPERIMENT XXVI. 
 
 Sand placed upon the hot iron, and water added, 
 open*d the gold leaf negatively. 
 
 EXPERIMENT XXVII. 
 
 Lump fugar placed upon the hot iron produced 
 no ele(5lricity till water was added to the burnt refi- 
 duum, which open'd the gold leaf pofitively. 
 
 EXPERIMENT XXVIH. 
 
 Powder'd charcoal was placed upon the hot iron, 
 and water dropped upon it, open'd the gold leaf 
 pofitively : but when water was dropped upon a red 
 hot piece of charcoal it caufed a negative repulfion, 
 
 EXPERIMENT XXIX, 
 
 Red and white port wine dropped upon the hot 
 iron produced negative repulfion when the iron was 
 fo hot as to produce no eledtricity with water alone, 
 which was tried before and after the wine. 
 
 EXPERIMENT XXX. 
 
 Rafberry wine dropped upon the hot iron pro- 
 duced pofitive eledricity. The rafberry wine and 
 red port were alternately dropped upon the fame 
 iron five or fix times fucceffively, which changed the 
 eledlricity from pofitive to negative each time. 
 Alfo feveral other fweet wines were tried, which as 
 well as fugar and water produced pofitive eledricity. 
 
 E EXP, 
 
66 NEW EXPERIMENTS 
 
 EXPERIMENT XXXI. 
 Frefh urine poured upon the hot iron produced 
 ftrong poiitivc eledlricity. 
 
 EXPERIMENT XXXII. 
 
 Milk poured upon the hot iron caufed a ftrong 
 negative repulfion, and even when water was added 
 to the burnt refiduum, except in fome inftances 
 when it was burnt very black, it became weakly 
 pofitive. 
 
 EXPERIMENT XXXIII. 
 
 Butter was burnt upon the hot iron, and water 
 added caufed a ftrong negative repulfion. 
 
 EXPERIMENT XXXIV. 
 
 Ale produced no eledricity till water was added 
 to the burnt refiduum, which became pofitive, 
 
 EXPERIMENT XXXV. 
 
 Dry tea leaves were burnt upon the hot iron, and 
 water added open'd the gold leaf pofitively, alfo 
 black pepper and tobacco. 
 
 EXPERIMENT XXXVI. 
 
 Sope firft burnt on the hot iron and then water 
 added, alfo fope and water mixed produced a ftrong 
 negative repulfion. 
 
 EXP. 
 
ON ELECTRICITY. 6/ 
 
 EXPERIMENT XXXVII. 
 Tin- foil was placed upon the hot iron which foon 
 melted, then water dropped upon it firft open'd the 
 gold leaf negatively, then weakly pofitive. 
 
 EXPERIMENT XXXVIII. 
 Alum burning on the hot iron produced no elec- 
 tricity till water was added to the burnt refiduum, 
 which caufed a ftrong pofitive repulfion. 
 
 EXPERIMENT XXXIX. 
 
 Moift fait of tartar was thrown upon the hot iron 
 which caufed the gold leaf to open ftrongly nega- 
 tive, its vapours condenfed fo quick upon the tube 
 ufed for trying the eleftricity, that it was with fome 
 difficulty that it cou'd be excited. 
 
 EXPERIMENT XL. 
 
 Saliva produced pofitive eleftricity. When wa- 
 ter alone was producing negative repulfion, fpitting 
 upon it wou'd immediately change it to pofitive. 
 
 EXPERIMENT XLI. 
 
 Yeafl was ftrongly pofitive, but not till water was 
 added to the burnt refiduum. 
 
 EXPERIMEN.T XLII. 
 Cotton and linen rags were burnt on the hot iron, 
 and water added, produced a weak pofitive repul- 
 fion. 
 
 E 2 EXP. 
 
6S NEW EXPERIMENTS 
 
 EXPERIMENT XLIII. 
 
 Sheep's wool, feathers, and hair, were burnt or^' 
 the hot iron, and when a fingle drop of water was 
 added, the gold leaf ftruck the fides of the electro- 
 meter pofitively. 
 
 EXPERIMENT XLIV. 
 
 Rafped horn and bone were burnt upon the hot 
 iron, which produced pofitive eledricity when water 
 was added, but not near fo ftrong as in the laft ex- 
 periment. 
 
 EXPERIMENT XLV. 
 
 Powder'd pit coal was placed upon the hot Iron, 
 which produced pofitive eledlricity upon the addi- 
 tion of water. 
 
 EXPERIMENT XLVI. 
 Frefh fheep's blood was dropped upon the hot 
 iron, which produced pofitive eledricity. 
 
 EXPERIMENT XLVII. 
 
 A hollow piece of bell metal about an inch thickj 
 and three inches diameter, was caft on purpofe to 
 repeat thefe experiments upon, moft of which were 
 again tried, but wii-'h no remarkable difference, ex- 
 cept that water produced negative eledtrlcity with 
 more certainty. Upon the iron it was fometlmes 
 negative, fometimes pofitive, but moftly none at 
 all ; whereas on the bell metal it was almoft always 
 negative. 
 
 EXP. 
 
ON ELECTRICITY. 69 
 
 EXPERIMENT XLVIII. 
 Vinegar produced no eledlricity when dropped 
 upon the hot bell metal, till water was added to the 
 burnt refiduum, which caufed a ftrong pofitive re- 
 pulfion. 
 
 EXPERIMENT XLIX. 
 
 The bell metal was at laft made too hot and 
 therefore broke to pieces as it was taken out of the 
 fire, I therefore again had recourfe to caft iron, and 
 for the fake of its holding fluid fubftances, I turned 
 a caft metal weight Co as to have a very fmooth 
 concave furface in the middle, and a concave rim 
 near the edge, fb that I cou'd place upon it feveral 
 fubftances at once without mixing. 
 
 The lean part of a leg of veal was chopped fmall, 
 and a fmall quantity placed upon the red hot cafl; 
 iron, which caufed the gold leaf to open pofitively, 
 but after burning fome time water was added, which 
 changed its eledlricity. 
 
 EXPERIMENT L. 
 
 The fat of veal was burnt upon the hot iron, 
 which produced no ele6tricity till water was added, 
 which caufed a ftrong negative repulfion both before 
 and after it was burnt black. 
 
 EXPERIMENT LI. 
 
 Nitre was put upon the hot iron, which melted 
 without producing eleftricity ; then water was drop- 
 ped upon it, which exploded without producing 
 E 3 anv 
 
70 NEW EXPERIMENTS 
 
 any elevftricity •, fometimes fmall globules of water 
 jfloated a coniiderable time upon the melted nitre, 
 and then fuddenly exploded without ever producing 
 any eledlrical repulfion or gradual evaporation, as 
 is ufual with other fubftances. 
 
 EXPERIMENT LII. 
 Bees wax produced ftrong negative eledlricity, 
 with the addition of water. 
 
 EXPERIMENT LIII. 
 
 Verdegreafe with water produced very weak po- 
 fltive eledcricity. 
 
 EXPERIMENT LIV. 
 
 Powder'd antimony fmoked much, and v;hcii 
 water was added the gold leaf open'd negatively. 
 
 EXPERIMENT LV. 
 
 Carraway feeds dropped upon the hot iron caufed 
 a ftrong negative repulfion without the addition of 
 water, alfo water added when they were burnt black 
 open'd the elecftrometer negatively. 
 
 EXPERIMENT LVI. 
 
 Hemp feed thrown upon the hot iron caufed a 
 weak politive repulfion, but when water was added 
 it became ftrongly politive. 
 
 EXPERIMENT LVII. 
 
 A tea fpoonful of water was dropped into the 
 
 ron- 
 
ON ELECTRICITY. ^1 
 
 concave hot iron which did not produce any repul- 
 fion, then fome powder'd gum arabic was added 
 which caufed the gold leaf to diverge pofitively, 
 then bees wax was alfo added which caufed it to be- 
 come negative. 
 
 EXPERIMENT LVIII. 
 Thefe two laft fubftances were dropped on the 
 hot iron in the reverfed order which firfl: produced 
 negative and then pofitive. 
 
 EXPERIMENT LIX. 
 
 Muftard feed was dropped upon the hot ironj, 
 which caufed no repulfion till water was added to 
 the burnt reilduum, which open'd the gold leaf 
 negatively. 
 
 EXPERIMENT LX. 
 
 Linfeed produced no electricity till water wa^ 
 added to the black refiduum, which open'd the elec- 
 trometer weakly negative. The iron was then 
 made hotter, and the addition of water produced 
 pofitive. 
 
 EXPERIMENT LXI. 
 
 Canary feed alfo produced negative by the addi- 
 tion of water till it was burnt very black and then 
 it became pofitive : alfo anife feed, and fennel feed^ 
 were like the canary. 
 
 E4 EXP. 
 
72 NEW EXPERIMENTS 
 
 EXPERIMENT LXII. 
 
 Burnt millet feed produced pofitlve eledlricity 
 with the addition of water. 
 
 EXPERIMENT LXIII. 
 Water added to burnt coriander and cummin 
 feeds, produced negative eledricity till the refiduum 
 had continued burning a long time, and then it 
 became pofitive. 
 
 EXPERIMENT LXIV. 
 
 Hitherto the eledtricity of the apparatus, whence 
 the vapours afcend, has been only examined. I 
 now fattened a piece of paper upon a bent wire, 
 which being placed in the cap of the eledlrometer 
 hung over the hot iron, fo that the vapours in af. 
 cending might pafs over the paper, and fhew whe- 
 ther this eledrical ftate wou'd in any inftance be of 
 the fame kind obferved in the veflel. 
 
 EXPERIMENT LXV. 
 
 The vapour of red port wine was tried as above 
 and found pofitive, contrary to the ftate of the iron 
 in exp. 29. 
 
 EXPERIMENT LXVI. 
 
 The vapour of rafberry wine was found to be ne- 
 gative contrary to the ftate of the iron in exp. 30. 
 Alfo wine made from bilberries, and fugar and water 
 xmixed, produced negative vapours. 
 
 EXP. 
 
ON ELECTRICITV. 73 
 
 EXPERIMENT LXVII. 
 
 The vapour of pure water was pofitive, but the 
 addition of a fmall quantity of faliva changed it to 
 negative. 
 
 EXPERIMENT LXVIII. 
 
 The vapour of raifin wine was firft pofitive and 
 then negative, and the reverfe when the iron was 
 examined. 
 
 EXPERIMENT LXIX. 
 
 As carraway feed produced negative electricity 
 without the addition of water, and therefore with- 
 out any vifible vapour except a little fmoke, the 
 paper fixed upon the eledrometer was feveral times 
 placed at different diftances above the hot iron, 
 whilft the carraway feeds were burning, but no elec- 
 tricity appeared. 
 
 EXPERIMENT LXX. 
 The fquare brick which fupported the hot iron 
 was placed in the middle of an earthen plate full of 
 water, and ftanding upon the eledlrometer, then 
 the hot iron being laid upon the brick and out of 
 the reach of the water, wool was burnt upon it, 
 and a fpoonful of water added ; lafi:ly, the whole 
 was cover'd with a glafs jar with its mouth immerfed 
 in the water that the vapour might not efcape with- 
 out touching the water j in this experiment no elec- 
 tricity appeared. 
 
 From 
 
74 NEW EXPERIMENTS 
 
 From thefe experiments it appears that various 
 mineral, vegetable, and animal fubftances when 
 evaporated, caufe a pofitive or negative divergency 
 of the eledrometer, and it was remarked in the be- 
 ginning of this fedion that M. de Saufilire attri- 
 buted thefe efFedts to the generation of a new quan- 
 tity o; the eleftrical fluid : but fince the ftate of the 
 electricity of the afcending vapour is contrary to 
 that of the infulated veflel whence it rifes, it now 
 feems more probable that the vapour thus produced 
 acquires its pofitive or negative ftate, becaufe its 
 affinity with the eledlrical fluid is greater or lefs than 
 that of the veflel, and that when a particle of vapour is 
 but juft in conta6l with the furface whence it rifes, 
 its capacity to become pofitive or negative is much 
 greater than when it is entirely furrounded with air ; 
 and thus if the vapour becomes pofitive by abforb- 
 ing eledtricity from the vefl*el, the vefl'el will be* 
 come negative and v. v. without the neceflity of 
 fuppofing a new quantity of the fluid to be generated 
 in this procefs. 
 
 SECT, 
 
©N ELECTRICITY. 75 
 
 SECTION V. 
 
 A defcription of a douhler of eleBricity by which a very 
 fmall quantity of ele^ricity may he augmented till it 
 beco7nes fenfible by common ele^rometers^ or vifible in 
 fparks. 
 
 THE great importance of a machine for the 
 purpofe of detedling very fmall quantities of 
 eledlricity has occurred to many eleclricians, as by 
 fuch an aflirtant it is to be hoped that important 
 difcoveries may be made in the atmofpheric eledlri- 
 city as well as in chemical experiments, wherein it 
 may be fuipe6led that elecTricity is combined with 
 other fubrtances. And many curious and well con- 
 trived electrometers have been made from the time 
 that Mr. Canton firft ufed his pith balls, till Mr. 
 Cavallo fubilituted fine wires and balls fufpended in 
 a glafs : but thefe as well as my gold leaf electrome- 
 ter were incapable of difcovering fuch very fmall 
 communications of eleAricity as were made fenfible 
 by Mr. Volta's condenfer, which by means of a thin 
 coated eledric is capable of receiving a much grea- 
 ter quantity of the elec5trical fluid than a common 
 infulated conductor of the fame dimenfion, which 
 fluid becomes fenfible by feparating the pofitive and 
 negative fides of the charged plate. On this inge- 
 nious contrivance Mr. Cavnllo made a very confi- 
 
 derabla 
 
76 NEW EXPERIMENTS 
 
 derable improvement by transferring the electricity 
 contained in the upper plate to another condenfer 
 of fmaller dimenfion, as explained in the philof. 
 tranf. vol. 72. 
 
 Yet notwithftanding the very great fenlibility of 
 this apparatus, atmofpheric eledlricity cannot al- 
 ways be difcovered by it, for inftance, when the 
 negative ftate of falling rain is nearly equal to the 
 pofitive ftate of the air thro' which it falls. 
 
 The following inftrument (which from its pecu- 
 liar manner of augmenting fmall quantities of elec- 
 tricity I have named the cledlrical doubler) will 
 render much fmaller quantities of eledlricity fenfible 
 than the above-mentioned double condenfer, unlefs 
 the firft condenfer exceeds the dimenfion of the fe- 
 cond as much as fhall render its power equal to a 
 given number of operations of the doubler, and fo 
 far they may be conftder'd as the fame inftrument, 
 for the doubler is only a condenfer multiplying its 
 capacity in geometrical progreftion : but this capa- 
 city augments fo quick that a double condenfer 
 equal to its power at the twentieth operation muft 
 be 40 yards in diameter if the doubler and fmaller 
 condenfer be only 2 inches. 
 
 The fenfibility of the doubler was evinced by 
 an eledrico-meteorological diary kept for above a 
 month, during which time I never failed to col- 
 led and dlftinguifti atmofpheric ele6lricity. This 
 diary I undertook at the requeft of my friend, Dr. 
 Darwin, who hoped fome important atmofpheric 
 difcoveries might be made thereby, and which ac- 
 companied 
 
ON ELECTRICITY. JJ 
 
 companled my defcrlption of the doubler prefented 
 to the Royal Society by the Dean of Lincoln, and 
 printed in the philof. tranf. vol. 'j^. 
 
 This inftrument in its firft and (impleft conftruc- 
 tion confifts of two polifhed brafs plates with infu- 
 lating handles. The handle of one is fixed on the 
 fide of the plate, and the other on the middle, and 
 ftanding perpendicularly, fee plate ift. 
 
 The plates are varnifhed on the underfide, and 
 the handles are made of mahogany, and fixed to 
 the plates by infulating nuts of glafs cover'd with 
 fealing wax. 
 
 The method of collecting eledlricity from the 
 atmofphere, and continually augmenting it till it 
 became fenfible, was thus performed. 
 
 In dry weather I carried into the open air a light- 
 ed torch not liable to be eafiiy blown out, or a fmali 
 lantern with a lighted candle in it, to the bottom of 
 which was fixed by means of a focket an infulating 
 handle of glafs cover'd with fealing wax. In the 
 other hand was carried a coated phial. Then ele- 
 vating the flame a little higher than my head I ap- 
 plied it to the knob of the phial, holding it in this 
 Situation about half a minute. By this means I 
 have found that more eledlricity may be collected 
 than by an exploring wire infulated and fixed to the 
 top of a church fteeple, as pradifed by F. Beccaria. 
 Having thus collefted a fufl'icient charge I return'd 
 into the houfe and applied the knob of the phial to 
 the cap of the gold leaf eledlrometer, upon which I 
 placed the plate (b) touching it with the forefinger 
 
 ftrctched 
 
y^ NEW EXPERIMENTS 
 
 ftretched over the infulatlng nut ; by this operation 
 the eledlricity contained in the phial fpreads upon 
 the cap which ferves as a condenfing plate, and elec- 
 trifies the plate (b) contrarily, becaufe it is conned- 
 ed with the earth, and the varnifh is interpofed as a 
 charged eledric. The phial being now removed 
 and the forefinger lifted up, the plate (h) is fepa- 
 rated from the cap, and the plate (c) placed upon 
 its upper fide and touched by ftretching a finger 
 over the nut of its infulating handle, this laft plate 
 is then eledrified contrary to (b) and the finger 
 being removed, and the plate (c) feparated from 
 (b) it will be evident to eledricians that the elec- 
 tricity of the cap and that of the plate (c) will be of 
 the fame kind, and nearly of equal quantity, fo that 
 the original charge is now doubled. 
 
 I then apply the edge of the plate (c) to the 
 fide of the cap, and placing (b) as before, and 
 touching it again, the eledlricity of (c) as well as 
 that of the cap, both aft upon the plate (h) and 
 the intenfity of its contrary eled:ricity becomes equal 
 to both ; then removing (c) which comes away 
 uneledrified ; 1 take off my forefingers from (b) 
 and lift it up, and placing (cj upon it 1 proceed as 
 before, thus continuing to repeat this doubling pro- 
 cefs till the gold leaf diverges fufficiently to exa- 
 mine the quality of its eleftricity ; or if the gold 
 leaf be firfi; taken out, the procefs may be continued 
 till fparks appear. 
 
 In rainy weather the knob of the phial was ap- 
 plied to the infulating handle of an umbrella, or to 
 
ON ELECTRICITY. 79 
 
 a torch carried under it, and in this manner I con- 
 tinued to examine atmofpheric eledricity, till I 
 conftrudled a more convenient apparatus defcribed 
 in fedion the eighth. 
 
 To prove that the ele£lricity is doubled, it may- 
 be obferved that the gold leaf opens to about twice 
 the diftance at each operation, and the application 
 of the plate (c) to the fide of the cap, or to a wire 
 placed in it, does not diminifh the divergency of 
 the gold leaf tho' in this fituation their eledtricity is 
 dilFufed over double the quantity of furface, and 
 admitting that the charge is doubled every time, 
 which is not far from the truth whilft the intenfity 
 is weak, the twentieth operation will augment the 
 iirft quantity of eleftricity above 300,000 times, 
 and this procefs even with a doubler in its original 
 and moft imperfed ftate may be performed in lefs 
 time than a minute. 
 
 SECT, 
 
Z0 NEW EXPERIMENTS 
 
 SECTION VI. 
 
 Improvements of the ele5lrkal doiihler^ with expert- 
 ments made to difcover the caufes and obviate the 
 inconvenience of its adhering or fpontaneous ele5iri^ 
 city. 
 
 SOME time after the conftrudion of my doubjer 
 of eledricity defcribed in the philof. tranf. 
 vol. yy, and in the above fedlion, I found that on 
 performing the doubling procefs a fufficient number 
 of times, it always produced eledlricity without pre- 
 vious communication, even after every method 
 likely to prevent it had been tried ; yet this impe- 
 diment was not fo great as to render the inftrument 
 ufelefs, for the adherent or Spontaneous eledricity 
 in the beginning of the procefs, when the inftru- 
 ment was cautioufly ufed, being very fmall, was 
 eaiily overcome by that which was communicated 
 in atmofpheric experiments, and in cafe of doubt 
 the atmofpheric eledlricity was diftinguifhable by 
 applying the bottle which collected it, to the two 
 firft plates alternately as mentioned in my defcription 
 of the inftrument. 
 
 However to deprive the doubler entirely of its 
 adherent or fpontaneous eleftricity, was thought a 
 defirable circumftance, as its fenfibility wou'd then 
 be much greater, and confequently it might with 
 
 more 
 
k 
 
 ON ELECTRICITY. Ol 
 
 Inore certainty be applied to the difcovery of new 
 eledrical fads, and which in this and the next fec- 
 tion I hope will be fufficiently proved. 
 
 Dr. Darwin, at the defire of Lord G. A. Caven- 
 difh, made the firft attempt with two plates moving 
 between two others by a lever, fo as to bring them 
 exa6lly to the fame pofition in each operation. 
 This contrivance he foon improved by another in- 
 ftrument in which the plates flood vertically and 
 moved by rack work in a direction exa6lly parallel 
 to each other. With this I tried whether the plates 
 wou'd 3.6k without any refinous fubflance, and found 
 that the interpofed air was a good fubflitute, and 
 hoped that now fince it was not neceffary to varnifli 
 the plates, nor bring them Into contadl, the fpon- 
 taneous eledtricity fuppofed to arife from the acci- 
 dental fridtion of the plates wou'd not be produced. 
 This inflrument was fent to Mr. Partington, and 
 the improvement of placing the plates near together 
 without varnifli was foon after mentlon'd to him in 
 a letter. 
 
 That I might accurately try whether the inftru- 
 ment wou'd be improv^ed by this omiflioii of var- 
 nifh, I made a doubler which confifled of three 
 plates flanding vertical and parallel, the middle plate 
 Aiding backwards and forwards between the two 
 others. The connexion between the two external 
 plates was performed by lifting up the fliding han- 
 dle, and the diflance of approach was adjufled by 
 fcrews which flopped the foot of the middle plate 
 any where between adual contadl and the fpace of 
 F half 
 
82 NEW EXPERIMENTS 
 
 half an inch. When this doubler was completed 
 and its infulating pillars entirely deprived of adhe- 
 ring eledricity by melting the furface of the fealing 
 wax which covered them, the doubling procefs was 
 tried, and it produced negative eledlricity at about ten 
 operations, fo that this inftrument tho* free from 
 all accidental excitement was yet poflefled of fpon- 
 taneous eledricity. But when I counted the doub- 
 lings and applied an infulated candle to the firft and 
 fecond plates alternately, I cou'd eafily colled and 
 diftinguiih atmofpheric elecflricity in a fmall room, 
 tho' the doors and windows v/erc fhut, this I tried 
 upon the fuppofition that the air would not be en- 
 tirely deprived of its eledricity by pafling through 
 fmall openings. 
 
 The next improvement I had in contemplation 
 was a revolving doubler, and before I had finifhed 
 my contrivance, I was informed that Mr. Nicholibn 
 had made one on the fame principles, and intended 
 to fend it me, I therefore attempted nothing more 
 till I received his very elegant and ufeful inftrument, 
 which Is much the beft mode of conftrufting my 
 doubler hitherto attempted. 
 
 This doubler confifts of two infulated and im- 
 moveable plates about two inches in diameter, and 
 a moveable plate alfo infulated which revolves in a 
 vertical plane parallel to the two immoveable plates, 
 pafling them alternately. See plate 2. 
 
 The plate A is conftantly infulated and receives 
 the communicated eledlricity. The plate B re- 
 volves, and when it is oppolite the plate A, the 
 
 conneding 
 
Pl^ltO 11 
 
eN ELECTRICITY. 83 
 
 connecfling wires at the end of the crofs piece D 
 muft touch the pins of A and C at E F, and 
 a wire proceeding from the plate B muft touch 
 the middle piece G, which is fupported by a brafs, 
 wooden, or other condu(5ling pillar in connedion 
 with the earth. In this pofition if ele6lricity be 
 communicated to the plate A, the plate B will 
 acquire a contrary ftate, and pafling forwards, the 
 wires alfo moving with it by means of the fame in- 
 fulating axis, the plates are again infulated till the 
 plate B is oppofite to C, and then the wire at 
 H touches the pin in C, conneding it with the 
 earth, and communicating the contrary ftate of 
 electricity to that of B but of the fame kind with 
 that of A. By moving the handle ftill further 
 B is again brought oppofite to A, and the connedt- 
 ing wires joining A and C. they both adl upon B, 
 which is conneded with the earth as before, and 
 nearly double its intenfity, whilft the eledricity of 
 C is abforbed into A ; becaufe of the increafed ca- 
 pacity of A, whilft oppofed to B, capable by its 
 connexion with the earth of acquiring a contrary 
 ftate fufficient to balance the influential atmolpheres 
 of both plates. 
 
 Thus by continuing to revolve the plate B, the 
 procefs is performed in a very expeditious and ac- 
 curate manner. 
 
 The ball ( I ) is made heavier on one fide than 
 the other, and fcrew'd upon the axis oppofite to the 
 handle, to counterbalance the plate B, which may 
 therefore be ftopped in any part of its revolution. 
 
 F2 Yet 
 
§4 NEW EXPERIMENTS 
 
 Yet notwithftanding the convenience and accu- 
 racy of this doubler it always produced fpontaneous 
 eledricity, even after all the refinous fubftances ufed 
 in its conftrudion had been melted over a candle, 
 and after (landing a long time with its plates in con- 
 nexion with the earth. I therefore conjedured that 
 this fpontaneous eledricity was not owing to acci- 
 dental fridlion, but to the increafed capacity of ap- 
 proximating parallel plates which might attradl and 
 retain their charge tho' neither of them were infu- 
 lated. To prove my hypothefis I firft endeavoured 
 more effedlually and fpeedily to deprive the inftru- 
 ment of the eleftricity laft communicated, and that 
 I might know whether this fpontaneous charge fup- 
 pofed to arife from the increafed capacity of the pa- 
 rallel plates, wou'd be always of the fame kind. 
 
 To efFe6t this deprivation I conneded the plates 
 A and C together by a wire hooked at each end 
 upon two fmall knobs on the backs of the plates, 
 the middle of the fame wire touching the pillar 
 which fupports the doubler. Another wire was 
 hooked at one end upon the back of the plate B, 
 and at the other end to the brafs ball which counter- 
 balances this plate. Thus all the plates were con- 
 nected with the earth, and by turning the handle of 
 the doubler, it might be difcharged of eledricity in 
 every part of its revolution. 
 
 After often trying this method of depriving the 
 doubler, I obferved that its fpontaneous charge was 
 almoft always negative. J then touched A and C 
 with a pofitively charged bottle, and turned the 
 
 doubler 
 
ON ELECTRICITY. 85 
 
 doiibler tlJl it produced fparks for a long time to- 
 gether; and after this ftrong pofitive charge 1 hooked 
 on the wires as above, and revolved the plate B 
 about an hundred times, which fo deprived the 
 doubler of its pofitive eledricity that when the 
 wires were taken off, it produced a negative charge 
 at about the fame number of revolutions which it 
 required before. 
 
 The pofitlvely charged bottle was again applied, 
 and the wires being hooked upon the plates, as 
 before, B was revolved only fifty times, yet this 
 was found fufficient to deprive it of its pofitive 
 charge, and in many experiments five or fix revo- 
 lutions were fufficient ; but I never thought it fafe 
 to fl:op at fo few, and have therefore generally turned 
 the handle forty or fifty times between every expe- 
 riment. 
 
 Left elecflricity adhering to the elecflrometer 
 fhou'd obftrudl the above experiments, I did not 
 let it ftand in contad with the doubler during its 
 revolutions, but touched the plate A with the cap 
 of the eledlrometer, after I fuppofed its eled:ricity 
 was become fufficiently fenfible : but left even this 
 contadl fhou'd communicate any eledricity, I made 
 a cap for my eledlrometer of fhell lac, having a 
 fmall tin tube in the center, to which the gold leaf 
 was fufpended within the glafs, and a bent wire was 
 fixed to the top which might eafily be joined to the 
 plate A of the doubler, and thus the gold leaf was 
 more perfedly infulated, and the eledlricity cou*d 
 F 3 not 
 
S6 NEW EXPERIMENTS 
 
 not be diffufed over fo large a furface. The glafs 
 which infulates the plates and crofs piece of the 
 doubler was alfo cover'd with fhell lac. 
 
 The doubler and ele(5lrometer being now well 
 infulated, I proceeded to try the following experi* 
 ments to afcertain whether the fpontaneous electri- 
 city was attracted by the approximation of uninfu* 
 lated parallel plates. 
 
 EXPERIMENT I. 
 
 The doubler was deprived of ele<5lricity by re- 
 volving the plate B forty times with brafs wires 
 hooked to all the plates, and during this depriva- 
 tion the electrometer was connedled with the plate A 
 by means of a brafs wire. I then took off the wires 
 whilll the plate B flood between C and A, in the 
 upper part of the plane of its revolution ; and turn- 
 ing the handle towards the right hand, the gold leaf 
 open'd negatively about a quarter of an inch, with 
 twenty-one revolutions. 
 
 EXPERIMENT II. 
 
 The doubler was deprived of eledricity, as 
 before, and whilft the plate B flood parallel to the 
 plate A, the brafs wires were taken off, then turn- 
 ing the handle forwards, the gold leaf open'd a 
 quarter of an inch negatively at the fixteenth revo- 
 lution. 
 
 Thefe experiments were repeated about thirty 
 times, and on difl"erent days, vv'ithout any confide- 
 rable difference in the refults -, the number of re- 
 
 volutions 
 
ON ELECTRICITY. 87 
 
 volutions being always greater when the plates fet 
 out from a fingle pofition than when the wires were 
 taken off whilll; A and B were parallel. 
 
 The plate B is placed at the diftance of i-i6th 
 of an inch from the other plates, and remains the 
 fame in the following experiments. It may be ne- 
 ceflary to note this circumftance, for doubtlefs the 
 number of revolutions, if not other refults wou'd 
 vary, if the plates were placed nearer or farther 
 afunder. 
 
 EXPERIMENT III. 
 
 A copper plate thirteen inches in diameter hav- 
 ing its furface rather convex, was furnifhed with an 
 infulating handle of oiled glafs, four inches long 
 and baked till the oil was well hardened. One end 
 of the glafs was fixed into a copper focket in the 
 middle of the plate, and the other end into wood, 
 that it might not be neceffary to touch the electric 
 part of the handle. This copper-plate was placed 
 upon a mahogany table, and the doubler being de- 
 prived of its electricity, the plate B was placed 
 parallel to A, fo that B was connected with the 
 earth, then the copper-plate was lifted up, by its 
 infulating handle, and applied to vhe plate A, and 
 laftly, the plate B being revolved only five times, 
 the gold leaf diverged negatively to the diftance of 
 a quarter of an inch. 
 
 EXPERIMENT IV. 
 
 Left accidental fridlion againft the mahogany 
 
 table fhou'd be objected, I lifted up the copper- 
 
 F 4 plate, 
 
S8 NEW EXPERIMENTS 
 
 plate, and after touching it with the point of a needle, 
 I applied it to the doubler, as before, and found 
 that the doubler did not produce its fpontaneous 
 electricity atlefs than 15 revolutions ; then touching 
 the plate again, I lower'd it till a part of its convex 
 furface touched the furface of fome water contained 
 in a large difh, and lifting up the plate, I applied 
 it to the doubler, which caufed the gold leaf to 
 diverge negatively at five revolutions, as in experi- 
 ment 3d. 
 
 EXPERIMENT V. 
 
 The plate B of the doubler was placed a little 
 beyond its former pofition, fo that its wire did not 
 touch the middle piece, and confequently tho' moft 
 of its furface was parallel to the plate A yet it was 
 infjlated. The copper plate was then applied to B 
 after it had touched the water as in the laft experi- 
 ment, and at the fame time the plate A was touched 
 by a brafs wire, to conneft it with the earth. About 
 five revolutions produced a very fenfible pofitive di- 
 vergency of the eledrometer, as might be expeded 
 in confequence of the negative charge being com-, 
 municated to B inftead of A, 
 
 EXPERIMENT VI. 
 
 By a frequent repetition of the foregoing experl-. 
 ments I was fully convinced of the attradion of elec- 
 tricity by approximating parallel plates : but hi- 
 therto the charge was negative, and fufpecting that 
 other fubftances might have a pofitive affinity with 
 
 the 
 
ON ELECTRICITY. 89 
 
 the fluid, and efpecially if my conjectures concern-- 
 ing projected powders and vapours were true •, I 
 therefore cover'd the furface of the copper plate 
 with a mixture of gum water and minium, alfo with 
 gum water and wheat flour, and found that thefe 
 fubftances when dried upon the furface of the cop- 
 per, changed its electricity, fo that when it was ap- 
 plied to the plate A, as in experiment 3d, it pro- 
 duced a pofitlve charge, and when applied to B, as 
 in experiment 5th, it produced a negative charge, 
 as might be expected If the painted copper plate by 
 its uninfulated approximation to the furface of the 
 mahogany table or water abforbed a poiitive charge, 
 
 EXPERIMENT VII. 
 
 To render the electricity of approximating plates 
 more confpicuoufly fenfible, 1 ground a brafs plate 
 three inches diameter with emery till It would adhere 
 to the furface of a piece of black marble. This 
 plate and marble therefore confliitute a condenfer in 
 its original ftate. The marble being moderately 
 warmed I prefled the brafs plate upon its furface 
 with the point of a brafs wire, then llftng It up by 
 its Infulating handle I applied it to the cap of the 
 electrometer, which caufed the gold leaf to ftrike 
 the fide negatively. 
 
 I hope it will now appear evident by the precau- 
 tions and experiments mentioned in this fecfbion, 
 and from the known laws of eledricity. 
 
 ift. That the doubler In its prefent ftate may be 
 deprived of accidental or communicated electricity. 
 
 ':^dly. 
 
90 NEW EXPERIMENTS 
 
 2dly. That the principal caufe of its fponta- 
 neous charge, is the attraction of electricity by the 
 approximation of its parallel plates. 
 
 3dly. That this charge may be pofitive or ne- 
 gative, according as the plates, or touching wires 
 are compofed of fubftances which have a greater or 
 lefs adhefive affinity v^ith the electrical fluid. 
 
 4thly. That the caufes of fpontaneous eleclricity 
 are common to the condenfer both in its original 
 and improved ftate, and to the doubler, and equal 
 in them all as far as they are equal in their dimen- 
 fions and powers. 
 
 5thly. That flnce the doubler may be compofed 
 of very fmall plates, and yet its power be equal to 
 that of a very large condenfer, its fpontaneous elec- 
 tricity will be more eafily overcome by a commu- 
 nicated charge than that of a condenfer of equal 
 power, and therefore experiments performed with 
 it will be lefs liable to equivocal refults ; and laftly 
 from thefe confederations I have ventured to pre- 
 fume that the inftrument may be advantageoufly 
 ufed and applied to the difcovery of new and inte- 
 refting fads in the fcience of ele(51:ricity. 
 
 SECT. 
 
ON ELECTRICITV. 9J 
 
 SECTION VII. 
 
 Experiments on the adhefive electricity of metals and. 
 other conducing fubjlances. 
 
 ' AVING fully proved by a frequent repetition 
 of experiments, that the pofitive or negative 
 fpontancous charge of the doubler depended upon 
 the abforption or repulfion of the eledrical fluid by 
 the approximation of its parallel plates, and that by 
 applying larger plates covered with minium or flour, 
 its eledricity might be changed at pleafure, it eafily 
 occurred, that if the fpontaneous electricity in the 
 beginning of the procefs was fufliciently weak, the 
 mere contad: of metals or other fubfta.nces having a 
 different adhefive affinity with the eledrical fluid 
 might alfo change it, and a new and interelting em- 
 ployment for the doubler be difcovered. 
 
 This fuppofed effett of contadl was confirmed by 
 the following experiments, in which the doubler 
 and eledrometer were deprived of eledlricity, and 
 ufed with the precautions and improvements men- 
 tioned in the laft fedion, 
 
 EXPERIMENT I. 
 
 The fpontaneous charge of the doubler having 
 been negative, and being deprived of this charge 
 by the ufual method^ the plate B was placed parallel 
 
 to 
 
9^ tJEW EXPERIMENTS 
 
 to the plate A, but fo that B was not conneded 
 with the earth. The plate A was then touched 
 with the blade of a knife, and the plate B at the 
 fame time touched with the point of a foften'd iron 
 wire. With fixteen revolutions the gold leaf di- 
 verged about one third of an inch pofitively. 
 
 EXPERIMENT II. 
 
 The doubler being deprived of eledricity as be- 
 fore, and the plate B placed as in the laft experi- 
 ment, the knife was applied to B inftead of A, and 
 the foft iron wire to A inftead of B, which opened 
 the gold leaf negatively at 15 revolutions. 
 
 Thefe experiments were repeated very often, and 
 the eledricity changed each time, being always po- 
 fitive in the plate touched by the knife. 
 
 To diftinguifli fo minute a difference of adhefive 
 eledricity, as that which might be fuppofed between 
 two metals fo nearly alike as harden'd fteel and foft 
 iron, wou'd appear incredible had not the frequent 
 repetition of experiments confirmed it. 
 
 Being now well convinced of this fad I tried many 
 other fubftances with various fuccefs, fometimes the 
 charge wou'd change regularly for a long time to- 
 gether, by applying the oppofed fubftances to A 
 and B alternately, as in the above experiments ; and 
 fometimes with other fubftances the charge wou'd 
 be quite uncertain. 
 
 But to remedy the uncertainty of the influence 
 of metals or other fubftances as far as pofTible, and 
 
 to 
 
ON ELECTRICITY. ^3 
 
 to exhibit the effedls of adhefive eleftricity to ad- 
 vantao-e, I made tables of experiments in which the 
 fubftances to be tried as were applied to A or B are 
 mentioned in the firft and fecond columns, the 
 number of revolutions in the third, and the ftate 
 of eledricity in the fourth. 
 
 The number of revolutions neceflary to caufe a 
 divergency of the gold leaf fufficiently fenfible, is 
 by no means offer'd as an accurate meafure of the 
 ftrength of adhefive electricity, but at prefent I 
 know of no better a way of comparing its effeds, 
 
 TABLE I. 
 
 3Lead Ore. 
 
 Lend. 
 
 Revolutions. 
 
 Elcdrlcltv^ 
 
 A.- 
 B. - 
 A. - 
 B. - 
 A.- 
 
 B. ^ 
 
 A.- 
 
 B. - 
 A.- 
 
 B. 
 
 A. 
 
 B. 
 
 A. 
 
 B. 
 
 A. 
 B. 
 
 A. 
 
 B. 
 
 A. 
 
 15. 
 
 15- 
 
 14. 
 
 13- 
 
 14. 
 
 13- 
 
 14. 
 
 13- 
 
 14. 
 
 P, 
 
 N. 
 P. 
 
 N„ 
 
 P, 
 
 N. 
 P. 
 
 N, 
 
 P. 
 
 TABLE 
 
94 
 
 NEW EXPERIMENTS 
 
 TABLE II. 
 
 Lead. 
 
 A.- 
 B. 
 A.- 
 B. 
 
 A. ■ 
 B. 
 B. 
 A.. 
 B. 
 
 B. - 
 
 Iron Wire. Revolutions. Ele£lrlclty, 
 
 -B. 
 -A. 
 -'B. 
 -A. 
 - B. 
 -A. 
 -A. 
 -B. 
 -A. 
 -A. 
 
 15. 
 
 13- 
 
 15. 
 16. 
 
 17- 
 16. 
 
 14. 
 
 20. 
 
 18. 
 
 N. 
 P. 
 
 N. 
 P. 
 
 N. 
 N. 
 P. 
 N. 
 N, 
 P. 
 
 TABLE III. 
 
 Lead Ore. 
 
 A.- 
 B. - 
 A.- 
 B. - 
 A.- 
 B. - 
 A.- 
 B, ~ 
 A.- 
 B. - 
 
 Iron Wire. Revolutions. Elfdlncity, 
 
 B. 
 A. 
 B. 
 A. 
 B. 
 ^A. 
 B. ■ 
 A. 
 B. . 
 A.. 
 
 15. 
 16. 
 22. 
 16. 
 
 17- 
 15. 
 16. 
 16. 
 
 17- 
 15. 
 
 P» 
 
 N. 
 
 P. 
 
 N. 
 
 P. 
 
 N. 
 
 P. 
 
 N. 
 
 P. 
 
 N. 
 
 TABLE 
 
ON ELECTRICITY. 9^ 
 
 TABLE IV. 
 
 Tin-foiJ. Iron Wire. Revolutions. Eleftridty. 
 
 A. B. i6. N. 
 
 B. A. i6. P. 
 
 A. B. 13. N. 
 
 B. A. 12. P. 
 
 A. B. 13. N. 
 
 B. A. 21. N. 
 
 A. B. 12. N. 
 
 B. A. 14. P. 
 
 A. B. 13. N. 
 
 B. A. 16. P. 
 
 TABLE V. 
 
 Zinc. Iron Wire. Revolutions. Elcdtrlcltyv 
 
 A. B. 16. N. 
 
 B. A. 17. P. 
 
 A. B. 15. N. 
 
 B. A. 21. P. 
 
 A. B. 15. N. 
 
 B. — ^ A. 24. P. 
 
 A. B. 15. N. 
 
 B. A. 18. P. 
 
 ^ A. B. 16. N. 
 
 5 A. B. 17. N. 
 
 (a. B. 15. N, 
 
 ^B. A. 22. P. 
 
 <B. A. 21. P. 
 
 Cb. A- 17. P. 
 
 In 
 
g6 NEW EXPERIMENTS 
 
 In the above five tables every experiment was 
 made by double contad, and fince the ftate of 
 eledlricity was evidently changed, (except in a few 
 inftances) whenever the two oppofed metals were 
 applied alternately to A or B, there remained no 
 doubt of the influence of thefe metals. Yet it was 
 not very apparent whether it was the pofitive flate 
 of the one metal or the negative ftate of the 
 other which prevailed. I therefore tried the 
 effedl of Angle contaft, choofing two metals whofe 
 eledlricity appeared to be contrary, and touching A, 
 C, and the crofs piece, whilft B ftood fingle in the 
 upper part of its plane, with a pofitive metal in one 
 experiment, and with a negative metal in the next, 
 or, or applying the fame metal to A, C, and the 
 crofs piece in one experiment, and to B in another, 
 but in this laft cafe B ftood in the lower part of its 
 plane. The reafon of varying the pofition of B 
 was, that the plate intended to acquire a contrary 
 ftate to that produced by contad, might firft be 
 brought into connexion with the earth ; thus when 
 A, C, and the crofs piece had been touched, B 
 came from its higher pofition into connection with 
 the earth when brought parallel to A, and might 
 then become contrarily eledrified ; and when B 
 had been touched in the lower part of its revolution, 
 C became conneded with the earth when B was pa- 
 rallel to it, 
 
 TABLE 
 
ON ELECTRICITY. 
 
 97 
 
 TABLE VI. 
 
 Revolutions. 
 
 Eleftricity, 
 
 14 
 
 Lead ore applied to A, C,7 
 and the crofs piece, - J 
 
 Zinc applied in the fame manner 18 
 
 Lead ore, - - - 13 
 
 Zinc, - - - 15 
 
 Lead ore, - - - 16 
 
 Zinc, - - - 16 
 
 Lead ore, - - - 15 
 
 Zinc, - - - 14 
 
 Lead ore, - - - 14 
 
 Zincj - - - 16 
 
 P. 
 
 N. 
 
 P. 
 
 N. 
 
 P. 
 
 N. 
 
 P. 
 
 N. 
 
 P. 
 
 N. 
 
 By experiments of fingle contact in the above 
 table, it now appears that the adhefive affinity of 
 eledricity to lead ore is pofitive, and to zinc nega- 
 tive. 
 
 G 
 
 TABLE 
 
98 
 
 NEW EXPERIMENTS 
 
 TABLE VIL 
 
 In which zinc is again tried by applying it to A 
 in the iirft fix experiments, and to B in the fix laft, 
 and alfo tried after the interval of feveral weeks 
 when the air was much more dry. 
 
 Zinc. 
 
 Revolutions. 
 
 Eleftricity. 
 
 A. 
 
 A. 
 
 A. 
 
 A. 
 
 A. 
 
 A. 
 
 B. 
 
 B. 
 
 B. 
 
 B. 
 
 B. 
 
 B. 
 
 12. 
 12. 
 II. 
 
 13- 
 
 lO. 
 lO. 
 
 13- 
 
 15- 
 
 12. 
 
 12. 
 
 13- 
 
 N. 
 
 N. 
 
 N. 
 
 N. 
 
 N. 
 
 N, 
 
 P. 
 
 P. 
 
 P. 
 
 P. 
 
 P. 
 
 P. 
 
 TABLE 
 
ON ELECTRICITY. 99 
 
 TABLE Vlir. 
 
 Lead ore applied to A and B alternately. 
 
 Lead Ore. Revolutions. Eleftricity. 
 
 A. 8. P. 
 
 B. 19. P, 
 
 B. 14. P. 
 
 B. 24. N. 
 
 B. 15. N. 
 
 A. 8. — P. 
 
 A. 7. --P. 
 
 A. 10. N. 
 
 A. 7. R 
 
 A.. 7,. — R 
 
 From thefe experiments it appears that the adhe- 
 iive eleftricity of the lead ore was not always fo 
 ftrong as to overcome the spontaneous charge of the 
 doubler. 
 
 G 2 Gold, 
 
ICO NEW EXPERIMENTS 
 
 Gold, filver, copper, brafs, regulus of antimony, 
 bifmuth, tutenag, mercury, various kinds of wood, 
 and ftone, were tried by this method of fingle con- 
 ta(5l and appear'd to caufe a pofitive charge. Tin 
 was negative, and a large piece of zinc much miore 
 weakly negative than a thin plate of the fame metal 
 ufed in the above experiments ; of thefe I defer 
 making tables till I have the opportunity of improv- 
 ing the accuracy of the doubler. This may be done 
 feveral ways which I fhall here defcribe, hoping that 
 fome more experienced eleftrician will approve and 
 execute them before I have leifure. 
 
 I ft. In the courfe of my experiments I found 
 that the force with which the touching wires pafTed 
 the pins on the back of the plates, had fome influ- 
 ence on the charge, which was alfo obferved by Mr. 
 Nicholfon, and it may reafonably be fuppofed that 
 the adhefive eledricity of thefe wires may have fome 
 efFedl. I wou'd therefore chufe fome metal which 
 has the leaft influence. Gold wire may probably be 
 the beft, and inftead of fmall wires to flirt againft 
 the pins, let ftronger wires move a rowel like that 
 of a fpur, and let the cheeks in which the rowel is 
 fixed be made to hold it harder or eafler by means 
 of a fcrew pafling thro' the center of the rowel. 
 Thus the contad of the touching wires may be re- 
 gulated by thefe fcrews, and may perhaps fo influence 
 the fpontaneous ele6lricity, that either A or B may be 
 made to prevail at pleafure or be exadly balanced. 
 
 2dly. It is evident that the capacity of the plates 
 is increafed as they approach to each other, and this 
 
 in- 
 
ON ELECTRICITy. lOI 
 
 increafed capacity will in many experiments caufe 
 them to abforb that kind of charge which agrees with 
 their own affinities, or of the touching wires, inftead 
 of being influenced by the fubllances intended to be 
 tried. Let the plate B be moveable upon its axis 
 tliat it may eafily be placed at any diftance, between 
 aflual contad and the diftance of half an inch from 
 the other plates, that a diftance may be found which 
 will produce the leaft fpontaneous charge, and be 
 more eafily overcome by an intended delicate com- 
 munication of eledtricity. It will be alfo necefTary 
 to regulate the diftance on account of the drynefs or 
 molfture of the air. In dry weather I have found 
 the fpontaneous eledtricity to become fenfible at fif- 
 teen revolutions or under, and in molft air at about 
 forty, the diftance of the plates and contadl of wires 
 being the fame in both. 
 
 3dly. The fpontaneous charge of fmall plates 
 muft be lefs than that of large ones, fo that adhefive 
 eledricity communicated by fingle contaft will be 
 more likely to overcome fuch charge, for which rea- 
 fon principally, as well as for reafons of convenience, 
 fmall plates are preferable •, perhaps the fize of a 
 {hilling wou'd be fufficient. 
 
 4thly. The plates fhou'd not be cover'd with 
 varnifti or lacquer, left they fhou'd retain ele6lriclty, 
 and to prevent tarnifhing, the plates may be gilt, 
 or made of the metal ufed for refledling telefcopes. 
 
 5thly. The fpontaneous charge is produced at 
 fewer or more revolutions according to the velocity 
 or regularity with which the axis cf the doubler is 
 G 3 turned 
 
I02 NEW EXPERIMENTS 
 
 turned, fo that a regular motion wou'd alfo add to 
 the perfe6lion of the inftrument, which might be 
 efFeded by means of a pendulum, and a vibrating 
 doubler wou'd perform the procefs as well or better 
 than any other. The wires touching with equal 
 force, and in regular time, wou'd be a confiderable 
 advantage with refpe<5l to the accuracy of experi- 
 ments, and a doubler of this conftrudion might be 
 made to continue its motion like a clock, fo that 
 infulated veflels containing chemical mixtures or 
 growing vegetables, might be placed fo as to receive 
 its fuperfluous eledridity, and be kept in a conftant 
 ftate of eledrification. 
 
 I will conclude this feftion with obferving that 
 fince eledricity, like all other known fluids, adheres 
 with more or lefs force to different fubftances, it af- 
 fords a fimple and very fatisfadory theory of the 
 excitation ofglafsand other eledrics, ufed in the 
 conftruftion of eledrical machines •, for when the 
 iilk flap is rubbed by the revolving glafs cylinder, 
 it is brought into clofe contad, and eledricity ad- 
 hering more forcibly to glafs is carried forward into 
 the open air, which air having not been render'd 
 negative like the filk, does not counterbalance the 
 furface of the glafs, and therefore its capacity being 
 lefien'd, it emits the charge it had juft abforbed. 
 The amalgamated cufhion affifts the procefs by 
 bringing a furface of a conducing quality and in 
 connexion with the earth into clofer contad. 
 
 SECT. 
 
GN ELECTRICITY. IO3 
 
 SECTION VIII. 
 
 Obfervations on atmofpheric ele^ricity colle^ed by the 
 Jiame of a candle. 
 
 BEFORE I defcribe my obfervations on this 
 fubjeft of enquiry, it may be proper to men- 
 tion fuch theory of atmofpheric elediricity as appears 
 to me confonant to the general operations of nature, 
 and deduced from the moft rational fyftems of 
 others, my own obfervation, or the contents of the 
 foregoing fedions, which the intelligent reader will 
 eafily apply to this purpofe. 
 
 The intention of beginning with the theory is to 
 give the reader, (who may not have attended to 
 atmofpheric electricity) an opportunity of feeing to 
 more advantage the principles which thefe obferva- 
 tions tend to confirm or illuftrate, and thereby ren- 
 der them more interefting and pleafant. 
 
 Atmofpheric electricity may be principally con- 
 fidered as it appears in two ftates of the air, that is 
 tranfparent and cloudy. 
 
 I ft. The tranfparent or clear air always contains a 
 great quantity of water in folution, and is generally 
 found to be in a ftate of conftant poiitive eledtrifi- 
 cation, yet not always of the fame degree of inten- 
 lity, nor is the atmofphere every where in the fame 
 ftate, for the higher regions from their more perfect 
 G 4 infu- 
 
104 NEW EXPERIMENTS 
 
 infulation, are more ftrongly ele6lrified than the 
 lower ftrata of air whence the earth is conftantly re- 
 abforbing this fluid, and the invifible vapours are 
 undoubtedly more or lefs denfe in different places 
 according to the quantity of evaporation and con- 
 denfation, depending on the variations of heat and 
 cold, fo that irregular fpaces of air, perhaps in the 
 form of clouds, yet invifible, will be eledrified po- 
 fitively or negatively ; and to reftore the equilibrium, 
 the appearances called falling ftars are produced. 
 Or if the equilibrium between much larger trads of 
 air is to be reftored, large meteors fuch as that of 
 the year 1783 fly with aiionifhing brilliance and ra- 
 pidity from one region of the air to another. 
 
 The aurora borealis is another eledrical appear- 
 ance frequently {qqh in a tranfparent atmofphere, 
 yet it is fometimes ken when there are clouds, and 
 is probably owing to the diffufion of electricity in 
 the higheft and moft rarified part of the atmofphere, 
 where the air is not fufficiently denfe to exhibit the 
 electrical fluid in the form of corrufcations or balls 
 of fire. 
 
 2dly. When vapours are fufficiently condenfed 
 to become vifible, the intenfity of their electrifica- 
 tion increafes, and if the clouds thicken fpeedily, 
 their fenfible electrical atmofphere fometimes ex- 
 tends to the diftance of feveral miles. This exten- 
 five atmofphere will act powerfully on the lower 
 firata of vapour, (which may be confidered as hav- 
 ing an imperfect connection with the earth} and 
 induce a negative ftate whofe intenfity will continue 
 
 in- 
 
ON ELECTRICITY. IO5 
 
 increafing with that of tKe fuper-Incumbent cloud, 
 till the equilibrium be reftored by tremendous claps 
 of thunder, with vivid corrufcations of lightning. 
 And if the cloud happens to be low, the earth itfelf 
 becomes its immediate opponent, and is fometimes 
 violently ftruck to the injury or deftrudion of its 
 vegetable or animal inhabitants. 
 
 Thefe are the chief and moft ftriking efFecSIs of 
 atmofpheric eledlricity, and to account for them on 
 the known principles of this fluid is the bufinefs of 
 my prefent attempt. 
 
 The firfl and moft difficult part of this invefliga- 
 tlon is to afcertain the general caufe of fenfible elec- 
 tricity in the air, and explain the particular manner 
 in which it is abforbed from the earth. But from 
 the late fatisfadlory experiments of MefTrs. Volta, 
 Lavoifier, De la Place, and De SaufTure, the eva- 
 poration of water by the fun's heat may be confident- 
 ly afligned as the true general caufe, and this opinion 
 I hope the reader will find in fome meafure ftrength- 
 en'd by the experiments contained in fedlion the 
 fourth. And from the experiments on approxima- 
 ting furfaces, and on adhefive eledlricity in the fixth 
 and feventh fe<ftions, I wou'd infer that when water 
 is raifed into the air by means of heat, eledricity 
 adheres more copioufly under fuch circumftances to 
 each riflng particle from the general laws of the at- 
 tradlion of cohefion, and the very great elafticity of 
 the electrical fluid ; for a rifing particle of water 
 may be confidered as in the fituation of the copper 
 plate, fedlion 6th, experiment 3d and 4th, that 
 
 is 
 
1C6 NEW EXPERIMENTS 
 
 is furrounded with air except that it is connedled 
 with the earth by one point of contadl. And if 
 there is a difference between air and water as to 
 their eledlive attradion of electricity, which from 
 numerous correfponding facts may eafily be admit- 
 ted, it follows that the fmaller the particles of water 
 are, the more they come into contact with air, that 
 is their furfaces bear a greater proportion to their 
 folidity, and confequently they partake the more of 
 the property of air as to their attraction of electricity ; 
 or the furface of air in contact with the water, has 
 in this {ituation, the opportunity of abforbing elec- 
 tricity thro* the above-mentioned touching point : 
 which electricity from the circumftances of approxi- 
 mation and contact, may be condenfed and the par- 
 ticle of water be pofitively electrified tho'uninfulated. 
 It is for the fake of perfpicuity that the vapour 
 is here confidered as rifing in the form of fmall glo- 
 bular particles : but however that may happen, the 
 electrical adhefion will probably be the fame : for if 
 the procefs of evaporation fhou'd not confift in the 
 afcenfion of globular particles raifed by heat, but 
 that it confifts in a chemical combination of heat, 
 air, and water, which inftantaneoufly form a tran- 
 fparent fluid, this compound fubftance may have a 
 greater adhefive affinity with electricity than the 
 furface whence it rifes, and therefore become pofi- 
 tively electrified. And this laft fuppofition is con- 
 fiderably illuftrated by the experiments contained in 
 feet. 4th, wherein it is (ten that the mixture of va- 
 rious mineral, vegetable, and animal fubftances, 
 
 with 
 
ON ELECTRICITY. IO7 
 
 with the evaporating water changed its adhefive 
 electricity. 
 
 Vapour thus afcending eleflrified, and being 
 combined with air and heat To as to form a perfedly 
 tranfparent fluid, is in its weakeft pofitive ftate, 
 till the heat pafles off either by diffufion in the cir- 
 cumambient air, by two currents of different de- 
 grees of rarity paffmg in contrary diredlions, or by 
 the higher part of the atmofphere moving with 
 greater or lefs velocity than the lower, each current 
 being more or lefs cold than the other. In any of 
 thefe fituations the vapour will be condenfed and 
 increafe the intenfity of its pofitive charge, and 
 fome fuch caufes ading at all times, produce acon- 
 ftant pofitive eledrification of the atmofphere, even 
 before the degree of condenfation is fufficient to 
 deilroy its tranfparency. 
 
 During a fpace of fifteen years, F. Beccaria never 
 obferved a ferene atmofphere to be negatively elec- 
 trified, except in four inftances, when there was 
 great reafon to believe it proceeded from the influ- 
 ence of difl:ant clouds. See his treatife on artificial 
 eleflricity. 
 
 When this kind of condenfation happens in the 
 higher and more infulated part of the atmofphere, 
 where no equilibrium can be reftored by an infen- 
 fible diffufion of electricity, nor by fl:riking fudden- 
 Jy into the earth, and when the intenfity of this elec- 
 tricity is increafed beyond the capacity of the va- 
 pour to which it is attached, it is formed into balls 
 of fire J for any fluid will form itfelf into a globular 
 
 figure 
 
I08 NEW EXPERIMENTS 
 
 figure from its own attradion of cohefion, if this 
 effecft be not prevented by adhefion to other fub- 
 ftances. Thefe balls of highly condenfed eledricity 
 then move off towards thofe parts of the air which 
 are leaft eleflrified, diffufing eledlricity as they pafs, 
 till they are wholly diiTipated and confequently dif- 
 appear. This diifipation may be plainly diftinguifh- 
 ed by a train of fire which often follows the meteors 
 called falling ftars. 
 
 The fame caufes may be fuppofed to occafion the 
 larger meteors, which being colletfled from and 
 diflipated in more extenfive regions of air, are more 
 luminous, and attended with one circumftance 
 which might be expeded from a very great accu- 
 mulation of electricity, that is a divifion of the ball 
 into feveral parts towards the end of its courfe. 
 
 Whoever has feen electricity emitted from a large 
 electrical machine, thro' a long and capacious ex- 
 haufled tube of glafs, may perceive a ftriking fimi- 
 larity between this experiment and the aurora bore- 
 alis, and may reafonably conjecture that the electri- 
 cal equilibrium being deftroyed in the higheft and 
 moft rarified part of the atmofphere is the occafion 
 of this appearance, and that It is very high is proved 
 by the converging direction of the ftreams •, and 
 iince the ftreams fometlmes appear to move about 
 confiderably, and to indicate an uncommon degree 
 of electrification, I have frequently been induced to 
 examine the ftate of the air with a very fenfible elec- 
 trometer, during a very luminous aurora borealis, 
 but cou'd not diftlngulih either an extraordinary 
 
 quan- 
 
 I 
 
ON ELECTRICITV. IO9 
 
 quantity or motion of electricity. Perhaps other 
 fituations mipht be more favourable for fuch obfer- 
 vations, and hence others have more confidently 
 affirmed that their apparatus has been affected 
 by it. 
 
 When the air has loft more of its heat and the 
 condcnfed vapour becomes vifible fo as to form 
 clouds or mifts, the intenfity of its electrification is 
 increafed, becaufe the water is now formed into 
 fmall globules whofe furfaces proportionally leflen, 
 as the globules increafe in diameter, and from Dr. 
 Franklin's experiment of the can and chain it has 
 been long known that leflening the quantity of fur- 
 face expofed to air, increafes the intenfity of elec- 
 trification. Mifts or fogs which are only thin clouds 
 near the earth are generally found to be electrified 
 ftrongly pofitive, fo that a kite having a metallic 
 ftring and raifed in mifty weather will produce pun- 
 gent- fparks. But when clouds fly over a tranfpa- 
 rent air, and are in a ftill ftronger ftate of electrifi- 
 cation, it often happens that their atmofphere drives 
 into the earth the electricity contained in the lower 
 ftratum of vapour, or that contained in fome part 
 of the cloud which from its fituation can be moft 
 eafily difcharged thro' its imperfectly conducting 
 connection with the earth. 
 
 A part of the cloud thus rcnder'd negative is 
 frequently feparated from the pofitive part, by the 
 different currents of wind, or when the higher part 
 of the cloud moves with more or lefs velocity than 
 the lower, in this cafe the negatived vapour will 
 
 pro- 
 
no NEW EXPERIMENTS 
 
 produce a feniible atmofphere, and hence the clouds 
 appear fometlmes pofitive and fometimes negative. 
 
 To illuftrate this effect of ftrong electrical atmof- 
 pheres, the reader may try experiment the 8th, 
 feet. 2d. And that a negative atmofphere will 
 become fenfible even upon a body floating in air 
 whofe pofitive flate is the only caufe of Aich atmof- 
 phere, is eafily tried by firfl caufing the air of a 
 room to be flrongly electrified pofitively, and then 
 a fmail flip of gold leaf thrown into the air will ac- 
 quire a negative flate as it leaves the hand, and 
 will be repelled by the approach of a finger or other 
 conductor. In this experiment the finger has a 
 fenfible negative atmofphere as well as the gold leaf, 
 tho' it be not infulated. 
 
 In fummer altho' the hygrometer indicates a drier 
 air, yet there is undoubtedly more evaporation, and 
 therefore more water combined with or diffufed in 
 the atmofphere . The furface of the earth is hotter, 
 and yet the higher part of the atmofphere, owing 
 to its tranfparency and diflance from the earth is not 
 heated in the fame proportion. In fhort every na- 
 tural procefs is quickened or retarded by the active 
 influence of the fun, and if vapours can now be 
 more fuddenly raifed, they may alfo be more fud- 
 denly condenfed, and under thefe and other favou- 
 rable circumflances, the clouds become electrified 
 to a much higher degree of intenfity, till the equi- 
 librium of the differently electrified fl:rata, is re- 
 ftored by explofions termed thunder and lightning. 
 
 Th^ 
 
ON ELECTRICITY. Ill 
 
 The concourfe of two oppofitely electrified clouds 
 has fometimes been thought the immediate caufe of 
 thunder, and it is certainly pofTible that fuch clouds 
 may now and then be driven by oppofite currents 
 fo as to caufe an explofion, but 1 think it is more 
 agreeable to the moft common appearances of the 
 clouds to account for it by the extenfive and power- 
 ful influence of electrical atmofpheres, whereby the 
 feveral parts of the cloud or furface of the earth are 
 render'd pofitive or negative, as explained above ; 
 for it will not otherwife be eafy to account for the 
 quick and frequent fucceiTion of explofions which 
 are perceived in a Angle and diftinct cloud, every 
 part of which is apparently moving In the fame di- 
 rection. But on the fuppofition of a negative ftra- 
 tum, occafioned by a powerful pofitive atmofphere, 
 as long as a rapid condenfation of water takes place, 
 fo long may a repetition of explofions be expected. 
 
 The following experiment may ferve to illuftrate 
 the procefs of atmofpheric explofions as far as relates 
 to the influence of powerful electrical atmofpheres. 
 
 Let two flips of gold leaf or rather white Dutch 
 metal be faft:en'd to a brafs ball fufpended by a filk 
 fl:ring, or other infulating fubfi:ance. Bring the 
 brafs knob of a charged bottle towards the points 
 of the metallic flips till they become charged with 
 electricity, which will caufe them to be repelled each 
 way from the knob of the bottle and ftand as in 
 plate 3d, fig. 3d. Continue to hold the bottle in 
 the fame pofition during a few feconds, and one of 
 the flips will bend towards the knob of the bottle 
 
112 NEW EXPERIMENTS 
 
 fig. 4, and ftrike it fuddenly, then it will ftand re- 
 pelled till its electricity be again diffipated. In this 
 manner it will continue to repeat the ftroke as long 
 as a fufficient quantity of electricity remains in the 
 bottle, unlcfs the air be very dry, and then this ex- 
 periment may fail, which with me has only hap- 
 pened twice. 
 
 After this fhort account of my ideas of atmof- 
 pheric electricity, I now proceed to defcribe the in- 
 flruments .1 have made ufe of in making obferva- 
 tions. 
 
 The mofl common apparatus hitherto ufed has 
 chiefly confifted of high pointed and infulated con- 
 ducting rods, or wires extending from the place of 
 obfervation to the top of an high building or fteeple, 
 and conneded with an eledtrometer, or the fmall 
 and Infenfible communications of eledlricity have 
 been colle6led by means of Mr. Volta's condenfer. 
 But thefe inftruments are generally either not fufE- 
 ciently fenfible, or they can only fliew the ftate of 
 atmofpheric electricity at intervals, whence the ob- 
 ferver lofes the opportunity of watching the momen- 
 tary and interefting change which happens in feveral 
 ftates of the atmofphere, efpecially during the paf- 
 fage of thunder clouds. 
 
 In fed. 2d, exp. 20th, 31^:, and 32d, it was 
 found that the flame of a candle was very ufeful in 
 rendering the atmofpheric eledlricity fenfible when 
 it could not be perceived by means of points ; this 
 I believe it does becaufe the effluvium of the candle, 
 which is of a conducing nature, becomes combined 
 
 with 
 
ON ELECTRICITY. II3 
 
 with air fo as to form a very compleat union, and 
 as the rarified air fo combined with phlogiftic efflu- 
 vium rifes upwards, it is continually fucceeded by 
 a frefli quantity, and hence the apparatus has the 
 opportunity of abforbing eledbricity much more co- 
 pioufly than the fharpefl: points. Confidering this 
 advantage I provided a deal rod about lo feet long, 
 (fee plate iii. fig. 2d,) and after the fmaller end was 
 well dried it was faftened into'^a long tinn'd iron 
 funnel with cement, fo that the funnel did no where 
 come within half an inch of the end of the rod ; by 
 this means it is kept dry, and the funnel is not fo 
 liable to be accidentally broken off as if it was in- 
 fulated by means of glafs. At the fmall end of the 
 funnel is fufpended the ring of a chain which fup- 
 ports a fmall lantern, containing a lighted candle. 
 To the lower and broad edge of the funnel a foftened 
 brafs wire is faftened, which is about the length of 
 the whole rod, and at the lower end is hooked to a 
 fmall ring near the thick end of the rod, that the 
 wire may not be liable to accidents when the inftru- 
 ments is taken down. When this apparatus is ufed, 
 a window is opened in the higheft room of the houfe, 
 and the rod is placed upon one ftrong nail and un- 
 der another, on one fide of the cafement, fo that 
 the lantern is elevated about 50 degrees. Near the 
 place to which' the rod is faftened is a ho'e in the 
 window frame of fufficient width to receive a tube 
 of glafs cover'd with fealing wax, on the end of 
 which is a bent wire. The hook of the brafs wire 
 is then taken from the ring, and hooked upon this 
 H infu* 
 
I 14 NEW EXPERIMENTS 
 
 infulated bent wire, which ftands at a proper height 
 to be connefted with the cap of a gold leaf eledlro- 
 meter, Handing upon a board under the wire, and 
 that the brafs wire may not be too much agitated 
 by the wind a ball of lead is hung upon it. In this 
 fituation it is plain that the atmofpherlc eledricity 
 coL'etfted by the candle will come down the brafs wire 
 and be communicated to the cap of the eledrometer, 
 or to any other inftrument. But as it very feldom 
 happens that the gold leaf does not diverge when 
 this apparatus is elevated, there is little occafion to 
 make ufe of a condenfer or doubler, nor even of a 
 candle when there are large clouds paiTing over or 
 rain falling. 
 
 OBSERVATION I. 
 
 May 2\th^ i"]^J. Several heavy clouds palled 
 from the N. W. and the above defcribed apparatus 
 being elevated, the gold leaf diverged fometimes 
 pofitively and fometimes negatively ; at laft a blacker 
 cloud approached and rain began to fall, which 
 caufed the gold leaf to ftrike the fides of the elec- 
 trometer negatively with increafing velocity till a 
 fialh of lightning and clap of thunder happened, 
 and at the inftant of the flafh the gold leaf fuddenly 
 fcarted open and then clofed, and gradually open*d 
 pofitively ftriking the fides about ten times, it then 
 ilowly clofed and open'd negatively, and again ftruck 
 the fides with increafing velocity till the fecond fialh 
 caufed the fame convulfive motion and fudden change 
 
 of 
 
ON ELECTRICITY. II5 
 
 of its eledricity -, this was repeated feveral times 
 during the paflage of the cloud. When the thun- 
 der was more diftant the opening of the gold leaf 
 was lefs but yet very fudden, and at laft the gold 
 leaf frequently ftarted open when no thunder was 
 heard, or flafh (zzn. 
 
 OBSERVATION II. 
 
 May iSthy 1787. Several jfhowers paffed over 
 and eledrified the apparatus firfl: pofitively as the 
 cloud approached, then it changed about the middle 
 of the fhower and ended negatively. 
 
 OBSERVATION III. 
 
 May 2Sib, lySy. The wind high and N. W.. 
 A fhower of rain came on which eledrified the ap- 
 paratus firft pofitively, the gold leaf continuing to 
 itrike the fides till the rain abated, then it became 
 negative and it continued to ftrike more flowly till the 
 rain entirely ceafed, when it again changed and flood 
 at about a quarter of an inch politive, and the fl-:y 
 became quite clear. 
 
 OBSERVATION IV. 
 
 June yih, 1787. Wind S. W. and brifk. A 
 fhower coming on caufed the gold leaf to flrike the 
 fides firfl negatively, then pofitively, and at the 
 end of the fhower again weakly negative. 
 
 H 2 OBSER- 
 
Il6 NEW EXPERIMENTS 
 
 OBSERVATION V. 
 
 June Sib, lySy. The fky was entirely overcaft 
 and fmall rain fell for feveral hours, which eledri- 
 fied the apparatus pofitively. 
 
 OBSERVATION VI. 
 
 June 2Sth, 1787. Wind W. Barometer 29. 
 Thermometer in the houfe 64° A little before one 
 o'clock in the afternoon, the apparatus was elevated 
 before the approach of a diftindl and heavy cloud. 
 The gold leaf diverged negatively flowly increafing 
 till it began to rain, it then ftruck the fides and con- 
 tinued ftriking till the rain ceafed, it then changed 
 to pofitive and continued ftriking whilft fair ; after 
 fome time it again became 'negative and ftruck 
 quicker whilft it again rained, and fome diftant 
 thunder was heard without moving the eledlrometer. 
 Expe(5ling more thunder, I hung up my watch near 
 the apparatus that I might note down the time and 
 changes of eledricity, as they occurred during the 
 paftage of the cloud. 
 
 Hour. Min. 
 
 I 7 Raining, eledlrometer ftriking quick ne- 
 gatively. 
 
 — 10 Eledlrometer ftriking more flowly. 
 
 — 12 Now changed to pofttive & opening flowly. 
 
 — 13 Thunder heard, ftriking flowly pofitive. 
 
 — 14 Very quick pofitive, yet raining. 
 
 — 15 More flowly pofitive. 
 
 ■ — 17 Changing to negative. 
 
 I 18 
 
-ON ELECTRICITY. II7 
 
 "Hour. MIn. 
 
 I 18 Quick negative. 
 
 — 20 Thunder at a diftance, ftill ftriking ne- 
 
 gative. 
 
 — 23 Still ftriking negative, raining flowly. 
 
 — 26 Still ftriking quick negative. 
 
 — 27 The gold leaf quite clofed. 
 
 — 271 Striking pofitively, yet raining flowly. 
 
 — 29 More flowly pofltive. 
 
 — ^o Rain ceafed. Eledrometer opening about 
 
 an inch pofitlvely. 
 
 — 34 No fenfible eledricity. Some drops of 
 
 rain falling. 
 
 — 2^ Gold leaf open'd about half an inch pofl- 
 
 tive, but decreafing. 
 
 — 40 Suddenly open'd pofltive, and then flow- 
 
 ly ftriking. Heavy drops. 
 
 — 43 Decreaflng pofitlvely. Raining. 
 
 . — 45 Eledricity infenflble. Raining flowly. 
 
 — 46 Slowly opening negatively. 
 
 — 47 i Slowly opening pofitlvely. 
 
 — 48 An inch wide pofltive. 
 
 — 49 The gold leaf agitated and pofltive. 
 
 — 49z Still agitated but changed to negative. 
 
 — 50 Opening negatively by ftarts till it ftrikes 
 
 quick. Raining faft. 
 
 — 52 Ceafes to ftrike, decreaflng faft. • 
 
 — 53 Changed to pofltive. 
 
 — 54 Striking pofitlvely. 
 
 — 5S The gold leaf ftruck the glafs inftead of 
 
 the tin-foil. 
 
 H3 I 56 
 
four. 
 
 Min. 
 
 I 
 
 56 
 
 — 
 
 51 
 
 — 
 
 59 
 
 2 
 
 
 
 — 
 
 I 
 
 _ 
 
 i\ 
 
 118 NEW EXPERIMENTS 
 
 Striking very quick pofitively. 
 
 Slovv'er and then very quick, ftill raining 
 
 very faft. 
 Diftant thunder. Changing to negative. 
 Striking quick negatively. 
 Decreafing negatively. 
 Opening pofitively to the diftance of an 
 
 inch. 
 
 — 2 Then changed to negative, and ftriking 
 
 quick. 
 
 — 4. Changed to positive, and then ftriking 
 
 quick. 
 -— 6 Changing to negative. 
 
 — 7 Striking quick negatively, 
 
 — S Striking quick negatively. 
 
 — 9 Striking quick pofitively. 
 
 — 10 Still quick pofitively, and raining faft. 
 
 Diftant ftcy brighter. 
 — • II More flowly pofitive. 
 
 — 12 Again quicker pofitive. 
 
 .^ — 13 Still quick pofitive. Sky clearing yet 
 raining. 
 
 — 14 Decreafing pofitively. 
 
 — 15 Opening negatively. Rain flower and 
 
 fky clearer. 
 
 — 16 Standing wide negatively. 
 
 — i6h Decreafing negative. 
 
 .— 18 Rain ceafed. Juft fenfibly pofitive. 
 
 18^ 
 
ON ELECTRICITY. 119 
 
 Hour. Mill. 
 
 2 i8i Sun fliining, and the gold leaf open'd to 
 half an inch negatively. 
 — 20 A quarter of an inch pof. Sky clear. 
 
 In this obfervation there are lo changes of elec- 
 tricity in lefs than an hour and a half. 
 
 OBSERVATION VII. 
 
 July 2d, 1787. Wind N. W. Barometer 29, 
 45. Thermometer 68, Six o'clock in the even- 
 ing. Unequal clouds covering the whole horizon, 
 which caufed a divergency of the eledrometer of 
 about half an inch pofitive. 
 
 OBSERVATION VIII. 
 
 Jnly I4.ib, ly^y. About two o'clock In the af- 
 ternoon. Wind N. E. Heavy Ihowers but clouds 
 uneven. The gold leaf opened negatively, and 
 moved irregularly till it flowly ftruck the fide, and 
 as the rain abated it opened lefs, but never changed 
 to pofitive. 
 
 OBSERVATION IX. 
 
 July istk, 1787. About half paft feven In the 
 evening. Wind S. E. An heavy fhowerof rain 
 falling, the gold leaf ftruck the fides quick pofitive- 
 ly, and continued to do fo about 10 minutes; it 
 then became weakly negative, and ftood at half an 
 inch negative when the rain ceafed. 
 
 H 4 OBSER, 
 
I20 NEW EXPERIMENTS 
 
 OBSERVATION. X. 
 
 July 15/Z?, 1787. About eight o'clock in the 
 evening another fhower came on which began to 
 open the gold leaf pofitively, increafing very flowly 
 tiil it ftruck the fides whilft the rain increafed, and 
 when the rain came down quickeft, it gradually 
 changed to negative. The clouds then appeared 
 very uneven, and often changed the electricity till 
 the obfervations were difcontinued. 
 
 OBSERVATION XI. 
 
 July lyth^ ^7^7- About 6 o'clock in the even- 
 ing. Wind N. W. A fhower of rain eledrified 
 the apparatus weakly negative during the fpace of 
 about half an hour without changing. 
 
 OBSERVATION XII. 
 
 July i^tb, 1787. About one o'clock in the 
 afternoon. Wind W. A heavy cloud approached 
 and electrified the apparatus negatively a confiderable 
 time v/ithout rain ; at lafl fome drops falling the 
 gold leaf ftruck the fides, and continued to do fo 
 till the rain ceafed without changing to pofitive. 
 The weather had been r9.iny for fome days. 
 
 OBSERVATION XIII. 
 
 Augujl 4tby 1787. Ten o'clock in the morning. 
 Wind W. Barometer 29. 15. Sky very clear, 
 The gold leaf opened jufl fenfibly pofitive. 
 
 OBSER« 
 
CN ELECTRICITY. 121 
 
 OBSERVATION XIV. 
 
 Auguji i2th, 1787. Wind W. Barometer 29. i. 
 Therm. 62° The fky was overcaft with uneven 
 clouds, and a heavy cloud approaching it rained 
 flowly, which gradually opened the gold leaf to the 
 diftance of an inch pofitively, then raining fafter it 
 fuddenly collapfed and changed to negative, open- 
 ing to half an inch whilft the rain ceafed. 
 
 Two other clouds foon followed, which began 
 pofitively and ended negatively as before. 
 
 A very extenfive cloud fucceeded the laft ^nd 
 open'd the eleftrometer pofitively, which continued 
 ftriking a fhort time ; then it changed and ftruck ne- 
 gatively during about half the rain ; it then changed 
 and ftruck pofitively during the remainder of the 
 lliower, and when the rain ceafed it open'd about 
 half an inch negatively, where it ftood for a few 
 minutes and then collapfed, the fky clearing. 
 
 OBSERVATION XV. 
 
 About five o'clock the fame day. The wind 
 N. W. A fhower began ftrongly pofitive and end- 
 ed negatively as before. About fix o'clock fome 
 uneven clouds paffed over and the eledlrometer di- 
 verged negatively without rain, then rain falling it 
 ftruck negatively a long time, then a heavier cloud 
 approaching it changed and ftruck very quick pofi- 
 tively, till the rain abated and the cloud was nearly 
 gone, when it again changed and was weakly nega- 
 tive till the rain entirely ceafed. 
 
 OBSER. 
 
122 NEW EXPERIMENTS 
 
 OBSERVATION XVI. 
 
 Juguft i4.ib, ijSy. About noon. Wind S. W. 
 Very extenfive clouds with fmall drizling rain, the 
 gold leaf opened about half an inch pofitively, which 
 continued with very little variation about half an 
 hour, it then rained fomev/hat fafter and the elec- 
 tricity changed and continued about the fame time 
 negative. 
 
 OBSERVATION XVII. 
 
 Augujl i6iby 1787. Nine o'clock in the morn- 
 ing. Wind quite calm. A thick mift. Eledro- 
 meter open'd half an inch pofitively, 
 
 OBSERVATION XVIII. 
 
 Jugujl iSib, 1787. Half paft twelve o'clock. 
 W^ind S. W. Thin white clouds had been paffing 
 over all the morning. A diftinifl black cloud ap- 
 proached and fome rain fell before the apparatus was 
 elevated, the elec5lrometer open'd pofitively and 
 continued opening but not ftriking till very heavy 
 drops fell, it then changed and ftruck the fides ne- 
 gatively till the rain ceafed. Its velocity abated 
 when it was fair, but continued- ftriking for about 
 five minutes, it then decreafed but continued open 
 negatively till another cloud approached, it then 
 open'd pofitively about half an inch, when it began 
 to rain flowly, as the rain fell it open'd a little 
 wider. 
 
 Hour, 
 
ON ELECTRICITY. I23 
 
 Hour. Min. 
 
 12 45 About an inch pofitive. Rain ceafing 
 and gold leaf collapfing. 
 
 — 47 Eledlricity infenfible. 
 
 — 47i Opening flowly negative. Cloud ap- 
 
 proaching nearer. 
 
 — 48 A few large drops falling. Half an inch 
 
 negative. 
 
 — 50 Still half an inch negative, but drops ceafed. 
 
 — 51 Decreafing. The clouds pafled off, and 
 
 another approaching. 
 
 — c,"] Still juft fenfibly negative. Cloud large 
 
 and likely to rain. 
 ' — S9 Beginning to rain. Opening to half an 
 inch negative, and then ftriking. 
 I o Raining fafter. Striking about twice in 
 a fecond. 
 
 — I Rain abated, yet ftriking negatively. 
 
 — 4 Yet ftriking negatively, but little rain. 
 
 — 5 More rain. Eledricity decreafing. Cloud 
 
 about half over. 
 
 — 6 Eledricity now increafing. 
 
 — 61 Striking negatively. 
 
 ' — 7 Striking quick negatively, yet but little 
 rain. 
 
 — 8 Still quick negative. More rain. 
 
 '— 10 So quick as to keep the gold leaf trilling 
 againft the fides. Heavy rain. 
 
 — 12 Rain fuddenly abating. Ceafed to ftrike, 
 
 and decreafing. 
 
 I 13 
 
124 ^'^"^ EXPERIMENTS 
 
 Hour. Min. 
 
 I 13 Changed to pofitive, ftriking flowly then 
 quick. Few drops. 
 
 — 14 Trilling pofitively. 
 
 - — 14* Slower pofitive. Very few drops of rain. 
 
 — 15 Quite fair, yet ftriking flowly pofitive. 
 
 Clear fky over. 
 
 — 17 Yet ftriking flowly pofitive. 
 
 — 19 Ceafed ftriking, and decreafing. Sun 
 
 fhining. 
 
 — 20 Wide pofitive divergency, but decreafing 
 
 very flowly. 
 
 — 24 Half an inch pofitive. 
 , — 25 Juft fenfibly pofitive. 
 
 — 27 Infenfible. Sky clear. 
 
 Thefe clouds began and ended pofitively, and 
 therefore it may be concluded that their proper ftate 
 was negative, which occafioned on all fides an in- 
 fluential pofitive atmofphere. 
 
 OBSERVATION XIX. 
 
 Jugtift 2Sib, 1787. Twelve o'clock. WindN. 
 Barometer 28. 63. Having rained all day, the 
 eledrometer open'd weakly negative, and fometimes 
 changed to pofitive for a fhort time, but was moftly 
 negative. 
 
 OBSERVATION XX. 
 
 Augufi 27/^, 1787. Two o'clock in the after- 
 noon. Wind N. Barometer 2^. 3. A fhower 
 
 came 
 
ON ELECTRICITY. I 25 
 
 came on which opened the gold leaf flovvly pofitive, 
 which continued opening and clofing whilft mod of 
 the rain fell, but did not ftrike the fide. When 
 the rain was nearly over it changed to negative, and 
 then ftruck the fides for a confiderable time after 
 the rain had ceafed. 
 
 OBSERVATION XXI. 
 
 Dec. iStb, 1787. Eleven o'clock in the morn- 
 ing. Mift covering the tops of the hills, which it 
 had done for feveral days, fometimes defcending 
 into the valleys. The gold leaf diverged ftrongly 
 pofitive : but upon the falling of fome fmall rain it 
 was found negative. The fame happen'd on the 
 20th. 
 
 OBSERVATION XXII. 
 
 Dec. i^th^ lySy. WindE. Small fnow falling 
 ^11 day. Gold leaf diverged ftrongly pofitive, tried 
 feveral times. 
 
 OBSERVATION XXIII. 
 
 Dec. lyih, 1787. Wind N. E. Snow melting. 
 A few white clouds. Electricity ftrongly pofitive. 
 
 OBSERVATION XXIV. 
 
 Jan. i/, 1788.- Winds. Avery thick mift, 
 yet its eledricity was but juft fenfibly pofitive, tho* 
 whilft the mift was accompanied with froft and with 
 an eaft wind it had been for feveral days fo ftrongly 
 pofitive as to be very fenfible without a candle. 
 
 OBSER. 
 
126 NEW EXPERIMENTS 
 
 OBSERVATION XXV. 
 
 Jan. id^ 1788. Wind S. Small rain. Elec- 
 tricity negative. 
 
 Jan. 6th ^ 1788. Wind S. Small rain. Elec- 
 tricity negative. 
 
 OBSERVATION XXVI. • 
 
 Jan. i6ih, 17S8. High weft wind. A cloud 
 paffed over and fome fleet fell. The eleArometer 
 diverged ftrongly pofitive. The fky then clearing 
 it became ftrongly negative, and decreafing changed 
 to a weak pofttive when the fky was quite clear. 
 
 OBSERVATION XXVII. 
 Feb. Sib, 1788. Wind E. Thick mift on the 
 hills, with fmall rain moft of the day. Eledricity 
 negative except when the fky appear'd brightening, 
 it then became pofitive a fhort time, and then when 
 more rain fell it became again negative, and con- 
 tinued fo moft of the day. Conftant rain feems 
 moftly negative, becaufe it probably forms a more 
 extenfive connecPcion with the earth by moifture 
 which weakens the pofitive and higher eledlricity, 
 and ftrengthens the influential negative atmofphere, 
 
 OBSERVATION XXVIII. 
 
 Feb. igib, 1788. Wind S. W. and gentle fnow 
 continued falling for feveral hours. The eledlro- 
 meter diverged about an inch pofitively. 
 
 OBSER- 
 
ON ELECTRICITY. llj 
 
 OBSERVATION XXIX. 
 
 Feb. 2.0th, 1788. Wind E. No froft but a 
 very thick mift. Gold leaf ftruck the fides pofi- 
 tively. 
 
 OBSERVATION XXX. 
 
 March 5/y??, 1788. Wind S. W. and gentle fnow 
 continued falling from noon to five o'clock, the ap- 
 paratus was elevated five times, and the gold leaf 
 ftruck the fides pofitively. 
 
 OBSERVATION XXXI. 
 
 March isth, 1788. Wind N. E. Snow had 
 lain on the ground about a week, with hard froft, 
 but now it was thawing and there fell fome fleet. 
 The gold leaf flowly ftruck the fides negatively. 
 
 OBSERVATION XXXII. 
 
 March i^th., iy^%. Wind N. E. brifk. Over- 
 caft but fair. Eledlricity infenfible with the candle, 
 never obfervcd fo weak before. 
 
 OBSERVATION XXXIII. 
 
 March iijl, 1788. Wind W. One o'clock. 
 A fhower of hail came on which caufed the eold 
 leaf to ftrike violently pofitive. A little before the 
 fhower ceafed it changed and ftruck negatively, and 
 continued negative after the hail ceafed and the fun 
 fhone for more than half an hour, flowly decreafing, 
 
 OBSER- 
 
128 NEW EXPERIMENTS 
 
 OBSERVATION XXXIV. 
 
 March lift, 1788. Wind W. Three o'clock 
 in the afternoon. A large cloud fucceeded the laft, 
 the negative ftate of the air having continued till 
 the cloud approached, which changed the elediricity 
 to pofitive, when being engaged this cloud could 
 not be examined. At four o'clock a very large 
 cloud came with rain, the eleftricity was found 
 ftrongly negative, the eledrometer could not come 
 within 12 inches of its ufual poiition without endan- 
 gering the gold leaf j towards the end of the fhower 
 it changed from negative to pofitive feveral times. 
 Once the change only lafted whilft the gold open'd 
 7d\6. clofed. At laft it continued to ftrike negative- 
 ly whilft the fky cleared, decreafing for about a 
 quarter of an hour, it then changed to politive now 
 fair, but a cloud approaching. 
 
 Hour. Min. 
 
 4 30 Eledriclty pofitive. Half open decrea-' 
 fing. 
 . — 31 Clofed. The cloud approaching faft. 
 
 — 33 Opening negatively. The edge of the 
 
 cloud nearly over. 
 
 — 34 Still opening negative very flowly. No 
 
 rain, very calm. 
 
 — 38 Little more opened. Cloud appears more 
 
 broken. 
 
 — 41 Slowly decreafing. 
 
 4 43 
 
ON ELECTRICITV. I29 
 
 Hour* Min. 
 
 4 43 A few drops of rain. Gold leaf almoft 
 
 clofed. 
 
 — 45 Qiiite clofed. No rain. Sunfhines thro' 
 
 a part of the cloud. 
 
 — 48 Still clofed. 
 
 — 50 Opening pofitlvely. No rain. 
 
 — ^6 Standing at half an inch pofitively. 
 
 5 o Slowly decreaiing. Cloud appears hea- 
 
 vier. 
 — - 4 Quarter of an inch pofitlve. No rain, 
 cloud ftill blacker. 
 
 — 9 Few drops of rain. Eledricity the fame. 
 — - 17 No drops. Eledricity rather increafed. 
 
 Cloud coming flowly. 
 
 — 19 Gold leaf diverges half an Inch pofitive. 
 
 No rain. 
 — - 21 Gold leaf rather decreafing. 
 
 — 23 Quite clofed. No rain. Cloud heavy. 
 
 — 25 Opening negative. No rain. 
 
 — 26 Half an inch negative. 
 
 «— 29 Rather wider. No rain. Cloud ftill over. 
 
 — 30 Clofed. Darker. 
 
 — 31 Opening pofitively. 
 
 — 32 Strikes flowly. 
 
 — 33 Striking quick pofitively, yet no rain. 
 
 — 34 Eledlrometer ftrikes at twelve Inches from 
 
 the wire. ' 
 
 — 35 A little rain. 
 
 — ^6 A clap of thunder, and fudden ftart of 
 
 gold leaf, yet pofitlve. 
 
 i 5 37 
 
130 NEW EXPERIMENTS 
 
 Hour. Mln. 
 
 5 1^ Raining fafter. Still pofitive. 
 
 — 38 Hailing faft, ftill pofitive, and ftriking 
 
 at twelve inches dillant. 
 
 — 39 Remarkable ftrong hail, ftriking quick at 
 
 twelve inches. 
 
 — 42 Still hailing. Eledlricity ditto. 
 
 — 44 Still large hail. Ele6lricity weaker. 
 
 — 45 Changed quick to negative, and ftriking 
 
 at twelve inches diftance. 
 
 — 46 Hail lefs. Eledlricity rather weaker. 
 
 — 47 Hail ceafed. Eledricity only opens ne- 
 
 gatively at three inches diftance. 
 •— 49 Fair. Eledrometer in contadl with the 
 wire now pofitive. 
 
 — 50 Gold leaf juft ftrikes the fides pofitively. 
 
 — 52 A flafti of lightning and crack quickly 
 
 following. A fudden ftroke of the 
 gold leaf which changed it to negative. 
 
 — 54 Striking negatively. 
 
 ■ — ^S Eledlrometer removed to the diftance of 
 1 2 inches, where it ftrikes quick nega- 
 tively. 
 
 — C)() Striking more flowly negative. 
 
 6 o Eledrometer replaced ftriking negatively. 
 
 Still fair. 
 
 — I Striking rather flower. 
 
 — 3 Still flower, and yet fair. 
 
 — 5 Gold leaf ftands about an inch wide ne- 
 
 gatively. 
 
 6 7 
 
ON ELECTRICITY. I3I 
 
 Hour. MIn. 
 
 6 7 Clofed, and then opening pofitively. 
 
 — 8 One inch pof. Small rain falling. 
 
 — 9 Strikes the fides pofitively. 
 ' — II Decreafing. Rain ceafed. 
 
 — 12 Clofed. Quite fair. 
 
 The firft thunder clap did not change the elec- 
 tricity ; the fecond changed it from pofitive to ne- 
 gative, contrary to former obfervations •, this muft 
 depend in fome meafure on the difl:ance. 
 
 OBSERVATION XXXV. 
 
 April iph, 1788. Nine o'clock in the morning. 
 Wind S. W. Sky perfedly clear having been 
 without clouds fince the evening before. The gold 
 leaf diverged about half an inch pofitively. 
 
 At twelve o'clock the fame day the divergency 
 was only about a quarter of an inch, and the fame 
 at eleven o'clock at night. 
 
 OBSERVATION XXXVI. 
 
 April 30/^, 1788, The wind N. E. and very 
 gentle. An hygrometer of whipcord, which moved 
 in a fpace of i6 inches, marked in inches and eights 
 moift and dry, reckoning up and down from the 
 middle of the fpace, ftood at 6 8 dry. The appa- 
 ratus was elevated at 3 o'clock, afternoon, and the 
 gold leaf opened half an inch pofitively. At half 
 pad 8 o'clock the hygrometer was rifen about an 
 I 2 inch, 
 
i32 MEW EXPERIMENTS 
 
 inch, and the gold leaf open'd (o wide as nearly to 
 flrike the fide. The weather all the time quite fe- 
 rene. The frilling of the dew appeared to increafe 
 the divergency of the gold leaf. 
 
 OBSERVATION XXXVII. 
 
 A'lay ly?, 1788. Seven o*clock in the morning. 
 Wind N. E. gentle, ferene, and perfedtly clear. 
 The hygrometer 3 ^ dry. The gold leaf nearly 
 ftruck the fide pofitively. 
 
 About 1 1 o'clock the fame day, hygrometer 5 1 
 dry, the gold leaf now opened cnly half an inch po- 
 fitively, ftill clear and hot. 
 
 At 12 o'clock the wind changed to S. W. yet 
 very clear and hot. The divergency was lefs than 
 quarter of an inch. Hygrometer 6 I dry. 
 
 At I o'clock, the wind S. Divergency i-i6th 
 of an inch. 
 
 At 2 o'clock the eleftricity quite infenfible, clear, 
 and very hot. Hygrometer 7 dry. 
 
 At 3 o'clock the gold leaf open'd I of an inch 
 pofitively. A few white clouds appear'd. Hy- 
 grometer 7 I dry. 
 
 At 5 o'clock, clouds fomewhat darker. Diver- 
 gency quarter of an inch. Hygrometer 7 » dry. 
 
 At 
 
ON ELECTRICITY. 133 
 
 At 7 oVlock, fewer clouds, very calm. Diver- 
 gency half an inch. Hygrometer 6 i dry. 
 
 Half paft 8 o'clock. Hygrometer 5 6-8ths dry. 
 Divergency only quarter of an inch. Sky now clear. 
 
 Eleven o'clock at night. Hygrometer 5 6-8ths 
 dry. Clear and calm. Divergency half an inch. 
 
 OBSERVATION XXXVIII. 
 
 Mny c^th^ 1788. 'Half paft 4 afternoon. Wind 
 N. E. Having been clear all day. Hygrometer 
 6 4-8ths drv. Divergency k inch politive. 
 
 At nine o'clock in the evening, Hygrometer 
 5 I dry. Barom. 29. 3. Clear and calm. The 
 gold leaf flowly ftrikes the fides pofitively. 
 
 OBSERVATION XXXIX. 
 
 May 6th ^ 1788. Near twelve o'clock at night. 
 Barom. 29. 2. Hygrometer 5 a dry. An heavy 
 fliower of rain lafted about half an hour, durino: 
 which the gold leaf continued ftriking pofitively, 
 and after the rain ceafed it continued a long time 
 ftriking pofitively, and never changed to negative. 
 Since the weather had been fo long dry, it is pro- 
 bable that the air was not fufficiently moift to con- 
 duct away the electricity, which wou'd have been 
 otherwife repelled by the atmofphere of the cloud. 
 
 I 3 OBSER^ 
 
134 NEW EXPERIMENTS 
 
 OBSERVATION XL. 
 
 May-iythy 1788. The wind N. E. whence it 
 had blown above a week without rain. Hygrome- 
 ter 5 dry. Barom. 29. 2. The air undoubtedly 
 very dry. The flips of Dutch metal were fufpend- 
 ed in the middle of a room as before defcribed, and 
 when the charged bottle was prefented the flips of 
 metal flood diverging and cou'd not be made to 
 ftrike the knob as ufual, which fliews that a certain 
 degree of moifl:ure in the air is neceflary to this ex- 
 periment. 
 
 OBSERVATION XLI. 
 
 May i^th^ 1788. Barom. 29. 15. Hygrome- 
 ter 5 dry. Clouds moving flowly from the north 
 and thickening in the fouth. at half paft 2 o'clock 
 the apparatus was elevated, and the eledrometer 
 ftruck the fides flowly pofitive for fome time, then 
 ftood flill at about an inch wide, and then flarted 
 clofer or wider feveral times, which was probably 
 occafioned by diflant thunder. 
 
 Hour. Min. 
 
 2 45 A fudden change to negative, which 
 open'd half an inch, and then clofed 
 and became pofitive. 
 ^ — 50 Opening and clofmg pofitively. Darker 
 
 in the fouth. 
 — . p,^ About quarter of an inch pofitive. 
 
 2 56 
 
Hour 
 
 MIn 
 
 .2 
 
 56 
 
 
 SI 
 
 > 
 
 58 
 
 
 
 59 
 
 3 
 
 
 
 
 2 
 
 — 
 
 3 
 
 ON ELECTRICITY, J35 
 
 Suddenly ftruck the fide pofitlvely. and 
 
 then ftood at \ of an inch. 
 Clofed. 
 Very jflowly opening negative. More 
 
 clouds. 
 An inch wide negative. 
 Suddenly collapfed, and then ftruck the 
 
 fides negatively. 
 Strikes flowly negative. 
 Suddenly pofitive, then clofed and open'd 
 
 negative. 
 
 — 4 Clofed fuddenly, and then again open'd 
 
 negative. 
 .-— 5 Suddenly changed to pofitive, and then 
 clofed and open*d negative. 
 
 — 6 Suddenly changed to pofitive, and then 
 
 ftriking negatively. 
 
 — 7 Diftant thunder heard, and the changes 
 
 of eledricity were fo quick that they 
 could not be dldindlly noted, 
 
 — 15 A flafh of lightning. 
 
 ■ — 17 Another flafii, and change from negative 
 to pofitive, and at the fame inftant a 
 loud clap. 
 
 — 18 A flafli, and Inftant change from negative 
 
 to pofitive. 
 
 — 19 Flafh and inftant change. 
 
 — 20 Flafii and clap, fudden clofing, but no 
 
 change to pofitive. 
 
 1 4 Z ''-3 
 
136 ' NEW EXPERIMENTS 
 
 Hour. Min. 
 
 3 25 Sudden change to pofitive, which con- 
 
 tinued fome time, then gradually 
 changed to negative. Darker but no 
 rain. 
 
 — 27 Sudden change to pofitive. 
 
 — 30 A very flow change from negative to po* 
 
 fitive. Beginning to rain. 
 
 — 31 Striking quick pofitively. 
 
 — 32 Thunder heard. Clofing, then fuddcn 
 
 opening pof. Rain ceafed. 
 
 — ^5 Flafh. Sudden cloie without changing, 
 
 more rain. Negative. 
 
 — 37 Flafn and fudden change to pofitive. 
 
 — 45 Heavy rain. Slowly opening pofitively. 
 — - 46 Striking flowly pofitive. Raining faft. 
 
 — 50 Sudden change to negative, and thunder 
 
 heard. 
 
 — ^5 Standing negative, then fuddenly ftriking 
 
 negative, and prefently again flopping 
 without changing. Diftant thunder. 
 Rain ceafed. 
 
 4 o Opening flowly negative with a waving 
 
 motion till it ftrikes. 
 
 — 10 Still waving negative. No rain. Sky 
 
 cover'd with cloud. 
 
 — 15 A little rain. Changing flowly to pofi- 
 
 tive. 
 
 — 22 Rain ceafed, ftill pofitive without a waving 
 
 motion. 
 
 4 30 
 
ON ELECTRICITY. I37 
 
 Hour. Min. 
 
 4 30 Changed {lowly to negative, without any 
 
 perceptible charge of weather. 
 
 — 2^ Several changes without rain, except at 
 
 the diftance of two miles. 
 
 — 38 Another change to negative. 
 
 — 43 Small rain, ftill negative. 
 
 — 48 Slowly raining •, ftriking negative •, then 
 
 waving and ftarting. 
 
 — 50 Raining fafter, ftill ftriking negatively. 
 
 — 52 Diftant thunder, without changing the 
 
 eleftricity. 
 
 — 54 Raining faft, ft-ill negative. 
 
 5 o Still raining faft, and electricity negative. 
 
 — I Suddenly changed to pofitive. Rain 
 
 abating. 
 
 — 2 Rain ceafed, ftill pofitive. 
 
 - — 4 Fair, and gold leaf ftriking pofitively. 
 
 Sky clearing. 
 - — 10 Still clearer. Politlve eledlricity de- 
 
 creafins^. 
 
 OBSERVATION XLII. 
 
 Mi-y 24/^, 1788. Ten o'clock at night. Ba- 
 rometer 29. 05. Hygrometer 6 dry. Very calm 
 and clear, with a very bright aurora borealis. The 
 atmofpheric apparatus was carried into a field, and 
 the ele(5lrometer confifted of a needle and a fpider's 
 thread, with a very fmall bit of gold leaf faften'd 
 to oiie end and both the needle and fpider's thread 
 
 were 
 
138 NEW EXPERIMENTS 
 
 were fufpended by means of the peg to which the 
 flips of gold leaf were ufually fattened. The fame 
 apparatus was alfo elevated in its ufual place, but 
 tho' the fpider's thread open'd flowly and ftruck the 
 fides pofitively, yet no agitation or other motion 
 happened, by which the eledricity of the aurora 
 borealis could be diftinguifhed from the common 
 eledlricity of ferene air. 
 
 OBSERVATION XLIII. 
 
 May 2Sth, 1788. Eleven o'clock at night, quite 
 calm and clear, a little appearance of aurora borealis. 
 Barom. 29. c6. Hygrometer 7 1. The fpider's 
 thread flrikes the fide, but not fo often as the even- 
 ing before. 
 
 OBSERVATION XLIV. 
 
 July 4tb, 1788. A large cloud cover'd the ho- 
 rizon, and it continued raining about two hours, 
 during which time the funnel without its lantern 
 was elevated, and the gold leaf changed its ele(5tri- 
 city ten times, beginning and ending pofitively, 
 
 OBSERVATION XLV. 
 
 July ^th^ 1788. Large dark clouds frequently 
 pafTed over \ therefore about 2 o'clock in the after- 
 noon a kite was raifed, with a foften'd brafs wire in 
 the firing about 200 yards long. When the kite 
 had been flying about an hour, a dark cloud ap- 
 peared at a great diftance, and changed the eledri^ 
 
 city 
 
ON ELECTRICITY. 13^ 
 
 city from pofitlve to negative, which increafed till 
 the cloud came nearly over, and fome large drops 
 of rain fell, and to fecure the ftring from being wet 
 I endeavoured to tie it on the oppofite fide of a poll 
 to which it was before faftened ; but when my hand 
 came near the firing I received fo fevere a fhock 
 that my arm was deprived of fenfatlon during a few 
 feconds, and I was obliged to let the firing go, 
 firfl terrified at the fuppofed lofs of my left arm, 
 and then gratefully rejoicing to feel the returning 
 fenfibility after rubbing with the other hand. The 
 explofion was heard at the diflance of about 40 yards 
 like the loud cracck of a whip. The kite was raifed 
 often before and fince this time, but without any 
 remarkable appearance. 
 
 OBSERVATION XLVI. 
 
 July 30//^, 1788. Ten o'clock at night. Ba- 
 rometer 29. 5. Hygrometer 4 6-8ths dry. The 
 fky clear and very calm. The aurora borealis very 
 bright. The apparatus with an eledrometer made 
 of a fpider's thread, was elevated, but no irregular 
 motion, or extraordinary quantity of eledricity was 
 perceived. 
 
 OBSERVATION XLVII. 
 
 Jugujl i6ih, lySS. About 12 o'clock. Wind 
 S. W. A large and well defined cloud pafTed over, 
 which as it approached open'd the gold leaf pofi- 
 tively i when about half over it changed and be- 
 came 
 
140 NEW EXPERIMENTS 
 
 came negative whilft very heavy drops of rain fell. 
 The gold leaf continued ftrlking negatively to the 
 end of the fhovver, and then continued dimlnifhing 
 about 20 minutes after the rain ceafed. 
 
 OBSERVATION XLVIII. 
 
 Auguft 2^th, 1788. Between i and 2 o'clock, 
 afternoon. Barometer 29. 02. Thermometer 62". 
 Hygrometer 6 dry. Two clouds pafil-d over, but 
 not quite perpendicularly, and the eledricity was 
 wholly negative, and continued negative during the 
 intervals ; a third pafied fome what nearer and began 
 negatively, but ended pofitively ; a fourth came 
 ftill nearer and blacker, which began and ended 
 wholly pofitive. No rain fell during the pafTage of 
 the iaft, and only a fmall quantity whilil; the two 
 firft were pailing. 
 
 OBSERVATION XLIX. 
 
 Auguft 2i^th^ 1788. Between 10 and 12 o'clock 
 in the morning. Barometer 29. 02. Therm. 60. 
 Hygrometer 5 6-8ths dry. Two clouds pafTed on 
 one fide, which eledrified the apparatus negatively ; 
 a fmall quantity of rain fell, and more at a diftance ; 
 a third cloud came diredlly over, and then the gold 
 leaf open'd pofitively till It was about half over, 
 and then it became negative without rain. 
 
 OBSER. 
 
ON ELECTRICITY. I4I 
 
 OBSERVATION L. 
 
 Jan. i^th^ 1789. Eleven o'clock in the morn- 
 ing. Wind E. Barometer 28. 8. Thermometer 
 on the north fide of the houfe 26 degrees. Hy- 
 grometer I J" dry, having been fro fly and the ground 
 cover'd with fnovv for feveral weeks. The wind 
 now ftrong and fnowing faft. The gold leaf con- 
 tinued llowly ftriking the fides pofitlvely. Another 
 obfervation was made during a fhower of fnow which 
 I omitted to note down, but found feveral changes 
 from pofitive to negative as in fliowers of rain. 
 
 FINIS. 
 
■^- 
 
 1 
 
 L. 
 
V