Joseph Priestley’s The History and Present State of Electricity is an eighteenth-century work of experimental philosophy: part chronicle, part laboratory report, part manifesto for a new kind of collaborative science. Written by an English clergyman and natural philosopher who was himself an active electrician, it traces the young science from its first fumbling observations to the dramatic discoveries of the 1740s and 1750s, and it does so with the materials of the science itself — quotations from original authors, close accounts of apparatus, and reports of experiments performed by Priestley and his correspondents. The edition preserved here is the corrected and enlarged third, published in London in 1775 and dedicated to the Earl of Morton, then President of the Royal Society.
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Priestley opens with three prefaces that amount to a defence of his method. History, he argues, offers scenes of gradual rise and progress that resemble the sublime; civil history stirs the passions but displays vice and misery, natural history shows variety without human sentiment, and the history of philosophy alone combines the advantages of both. He promises a full but succinct narrative, quotes the original authors at length, avoids controversy, and quietly restores credit to discoverers who had been wronged. He thanks Dr. Watson, Dr. Franklin, and especially Mr. Canton for original communications, and he urges studious persons to take up electrical experiments on the grounds that they are clean, elegant, and cheap — an endless fund of knowledge, he says, that would amaze even Sir Isaac Newton. The second preface records his labour in learning High Dutch so that he could digest German books he had not seen, and laments that philosophers lack a common language; the third reserves post-1769 discoveries for a future continuation.
From the Sulphur Globe to the Leyden Phial
The Book’s Public Face: Dedication and Prefaces
The volume opens with the apparatus of eighteenth-century learned publication: a digitization notice recording that the book was scanned from a library copy and has passed into the public domain, a title page announcing the third edition of 1775, corrected and enlarged, and a dedication to James, Earl of Morton, then President of the Royal Society. Priestley’s first preface sets out his purpose. The history of electricity, he writes, offers scenes of gradual rise and progress that resemble the sublime; and among the branches of history, the history of experimental philosophy uniquely combines the passions stirred by civil history with the order and uniformity of natural history, without the vice and misery of the one or the coldness of the other. He thanks Dr. Watson, Dr. Franklin, and especially Mr. Canton for materials and original communications, along with Dr. Price and the Reverend Mr. Holt of Warrington. He promises a full but succinct account, quoting original authors, avoiding controversy, and silently restoring credit to discoverers who had been wronged. Electrical experiments, he urges, are clean, elegant, and cheap, an endless fund of knowledge; the electric fluid acts everywhere and may open new worlds, enough to amaze even Newton. He calls for the subdivision of philosophy and for small societies with directors of experiments, and wishes such societies would fund ships for discovery by sea and land. The preface closes with quotations from Dr. Hartley on piety and temperance in study, and is dated March 1767. A second preface, dated Leeds in January 1769, explains that his catalogue method brought him books he had not seen, mostly German, so that he learned High Dutch to digest them; he regrets that philosophers lack a common language, and notes that this edition adds three entire sections of original experiments, sold separately. The third preface adds that he has reserved post-1769 discoveries for a future Continuation, improved his accounts of the Academicians del Cimento and Mr. Du Fay from original publications, and records that Mr. Le Roi, secretary of the Paris Academy, was the first in France to adopt Franklin’s theory and demonstrated its principles by original experiments in two memoirs.
Boyle’s Effluvia and the First Glimpses of Light
The historical narrative proper begins with Mr. Boyle, who found that warming and wiping an electric before rubbing let a body no bigger than a pea move a freely poised steel needle three minutes after rubbing ceased. Smoothness helped, yet one rough diamond surpassed every polished stone he had met. Excited electrics attracted all kinds of bodies promiscuously, unlike the loadstone, which acts on one kind of matter only; amber attracted even powder of amber. Boyle showed the attraction did not depend on the air by suspending excited amber over a light body in a glass receiver and attracting it after the air was pumped out—though Beccaria would later deny attraction in a perfect vacuum. He also found that the electric was itself sensibly moved by the approach of other bodies, a fact that should not surprise us, since action and reaction are universally equal, though that axiom was not well understood until Newton. Boyle caught a glimpse of the electric light: the diamond Mr. Clayton brought from Italy shone in the dark when rubbed, and became electrical by the same treatment. Light bodies, such as feathers, clung to his fingers after being attracted. His theory held that the electric emitted a glutinous effluvium which seized small bodies and carried them back on its return; James Hartman, in the Philosophical Transactions, claimed to prove this by distilling a black balsam from colophonia and depriving it of its attractive power, leaving only a caput mortuum.
Guericke’s Sulphur Globe and the First Repulsion
Otto Guericke, Burgomaster of Magdeburg and inventor of the air-pump, melted sulphur in a hollow glass globe and broke away the glass, never imagining the glass globe itself would have served as well. Mounted on an axis and whirled in a wooden frame while rubbed with the hand, it performed every electrical experiment then known. To Guericke belongs the discovery that a body once attracted is repelled by the excited electric and not attracted again until touched by something else; he kept a feather suspended above his globe for a long time, and saw it instantly retreat to the globe when driven near a linen thread or candle flame without contact. He noticed the hissing sound and the light, which he compared to sugar pounded in the dark. His most remarkable experiments rested on the property that bodies immersed in electric atmospheres are themselves electrified, with electricity opposite to the atmosphere’s: threads near his globe were repelled by his finger, and a feather repelled by the globe always turned the same face toward it, like the moon toward the earth—an experiment later electricians seemingly overlooked.
The Academy del Cimento and Dr. Wall
The Academicians del Cimento ranked electrics by strength, from yellow amber and sealing wax down through the gems to glass and crystal, and used amber for all their experiments. They found it attracted smoke but not flame, and observed a visible electric atmosphere—the attracted smoke clinging to the amber like a small cloud and rising again as the amber cooled—later re-discovered by Franklin. Flame presented to the amber stripped it of all attractive power. All fluid substances, mercury included, responded to its attraction; presented to a large surface of liquor, the liquor rose toward the amber in a small pointed eminence, best seen in oil or balsam, an observation Mr. Grey would make again. They could not manage to rub amber in vacuo with any effect, nor make it act in confined air; they confirmed Boyle’s finding that excited amber suspended by a thread was attracted by bodies presented to it; and they found that amber dipped in oils, tallow, fat, and butter lost its power—substances now classed as non-conductors. Boyle, Guericke, and these gentlemen worked at about the same time and seem to have drawn no advantage from one another’s labours. Dr. Wall, pondering artificial phosphorus—an animal oil coagulated with a mineral acid—conjectured that amber, a mineral oil coagulated with a mineral volatile acid, might be the source of a much finer electric light than Guericke’s globe had shown.
Grey and Wheeler: Electricity Through Matter and Vacuum
Mr. Grey, probably unaware that Boyle had already done it, suspended excited glass and other bodies in an air-pump receiver and found they attracted at nearly the same distance in vacuo as in open air, provided the electric was brought to the light bodies at the same interval after excitation. In August 1732 he and Mr. Wheeler hung a white thread from the top of a receiver; exhausted and rubbed, the receiver drew the thread vigorously. When the excited tube was slowly withdrawn the thread returned to the perpendicular, but removed hastily it jumped to the opposite side—an effect they traced to the motion of the air shaking off the attraction on one side only. An excited tube attracted the thread through a second receiver placed over the first; Wheeler later found the attraction through five receivers stacked and exhausted, and thought it rather stronger than through one.
Nollet’s Experiments and the Medicated Tubes
The Abbé Nollet worked through a series of practical puzzles about how electricity moves and how it is lost. A glowing-hot iron, he found, produced no electricity in an excited tube, and he suspected the tube’s own charge was simply carried off through the iron. The focus of a burning mirror, by contrast, did nothing to drain an excited tube. Flame was already known to destroy electricity, and Nollet watched a candle’s flame stir visibly when an excited tube drew near; since the thinnest glass or any substance placed between candle and tube stopped the dissipation, he reasoned that effluvia streaming from the candle were to blame. A light body on a non-electric stand moved more briskly than on an electric one, and experiments went best with many spectators crowded close—so long as their perspiration did not moisten his glasses, a detail Mr. Wilcke would later explain. Moistening a pointed iron bar with water or spirit of wine made the blast from its point feel stronger, which Nollet put down to the electric fluid carrying off particles of the liquid. Excited electricity gave an odd sensation on the face, like a spider’s web, rarely produced by communicated electricity, and could be detected by smell more than a foot away. Melting sulphur in a glass globe over coals, he saw small pieces of sulphur attracted and repelled by the glass within while ashes were attracted without; down clinging to excited sulphur held fast when he presented an excited glass tube in his other hand.
Experiments in Vacuo and the Measure of Charge
The Abbé Rollet carried the work into exhausted vessels. Glass and other electrics could be excited in vacuo, though less strongly than in open air, and the electric light there was more diffuse and unbroken. When he inserted a conductor’s extremity into an exhausted glass vessel, the vessel filled with light whenever he brought his hand to it, brightened further when he spread his hand over it, and seemed wholly full of light when a spark was drawn; small pieces of metal inside clung close to the glass but detached at the approach of a finger or any outside conductor. M. Monnier asked whether communicated electricity was proportional to solid or to superficial contents. An anvil of two hundred pounds gave but an inconsiderable spark, while a tin speaking-trumpet of ten pounds, eight or nine feet long, gave a spark almost equal to the Leyden phial’s shock. A lead ball an inch in diameter matched a thin piece of lead of the same surface shaped into a hoop; a thin, long strip electrified along its whole length gave a very strong spark, but a very small one when rolled into a lump. Since a square piece of lead fell short of a spark from the same quantity of surface drawn out longer, he concluded electrification is stronger in proportion to surfaces, and among equal surfaces the longest has the advantage.
Tables of Excitability and Curious Observations
Mr. Boulanger set out to rank substances by how readily they could be excited, tabulating his results with the least excitable first in every column. His inference was that the most brittle and most transparent substances are always the most electric; marcasites, which could not be excited at all, he explained away with an awkward hypothesis about condensed air trapped inside them. Mineral waters, he reported, were more sensibly affected than common water, and black ribbons were sooner attracted than those of other colours, with brown and deep red next. Mr. Le Cat, a physician at Rouen, hung pieces of leaf gold at his conductor and saw them settle at different distances according to size—smaller pieces nearer, larger farther off—which he likened to the distances at which the planets revolve about the sun, supposing the same cause at work; he compared the newly discovered electric shock to thunder. Mr. Gordon of Erfurt electrified a cat so strongly that the charge was communicated through iron and spirit of wine. Mr. Jallabert of Geneva showed that a coating of pitch did not stop a conductor from being electrified, proving the fluid enters the substance of metals, and proved ice a conductor by freezing the water inside a Leyden bottle and still making the experiment work.
Flannel, and Lights from the Body
The first account of woollen garments showing electricity when taken off, after such flashes were known to be electrical, came to the Royal Society from Mr. Coke of the Isle of Wight, on the report of a lady of his acquaintance. The effect turned out to belong only to new flannel; after some wearing the property vanished, and washing destroyed it. The same appearance returned in frosty weather, when the texture was purer and all bodies, hairs excepted, are more elastic and capable of stronger vibrations; flannel damped with sea water and then dried heightened the display. Similar sights had been noted long before anyone knew their cause. Bartholin, writing around 1650 in his book on the light of animals, gave unctuous effluvia a large share in such appearances, reporting that Theodore Beza could be seen by a light from his eyebrows and that sparks would flash from the body of Charles Gonzaga, Duke of Mantua, when gently rubbed—though he does not say whether the duke’s skin was notably hairy or scaly. Dr. Simpson, who published a—
Franklin and the Leyden Phial
Franklin insulated his rubber and hung a phial to his conductor; it would not charge even with a hand held constantly to it, since the electric fire might leave the outside of the phial but none was collected by the rubber to carry it inside. Removing his hand and running a wire from the outside coating to the insulated rubber, the phial charged with ease: the very fire that left the coating travelled by rubber, globe, conductor, and wire into the inside. This set him observing more than other philosophers had. The phial electrified as strongly held by the hook with its coating applied to the globe as the other way round, and the same explosion and shock followed whichever part was held and whichever touched. To take a charged phial by the hook without diminishing its force, it must first be set down on electrics per se. A man holding one fully charged and one uncharged phial and bringing their hooks together took but half a shock, both remaining half electrified. Two phials charged through their hooks made a cork ball on silk between them first attracted, then repelled by both; but if one were charged through the wire and the other through the coating, the ball played vigorously between them till nearly discharged. Franklin did not then notice that two phials charged through their coatings would both repel the ball, as when both were plus; later, finding that two bodies electrified minus repel one another, he seemed surprised and owned he could not satisfactorily account for it.
Cigna’s Ribbons and the Coating Question
Cigna’s experiments on silk and glass turned on a simple question: when rubbed silk grows electric, does it take its charge from the rubber or from the body it lies on? Loose, open-textured silk, he found, answered to the substance beneath it—black behaving as resinous, white as vitreous—while close, hard silk answered to the rubber, provided the rubber gave up much electricity to the glass. A white silk stocking rubbed with gilt paper on glass came out resinous and left the glass vitreous; firm silk laid on glass turned vitreous and the glass resinous when rubbed with sulphur. Rubbed silk, in short, took its electricity from whichever body offered the greater friction or was the fitter to electrify glass.
He used these ribbons to illustrate Symmer’s clinging stockings. An electrified ribbon laid on an insulated lead plate was attracted only feebly; a spark drawn off with the finger left it clinging vigorously, and both bodies then showed no electricity at all—until they were parted, when both appeared electrified and a spark passed. Two glass plates on a smooth grounded conductor behaved the same way, adhering to each other and to the conductor, and a thin lead plate could be held up by attraction alone. Parted from the conductor but kept together, both plates showed vitreous electricity on their outer faces while the insulated conductor had contracted resinous electricity; separated, the upper plate held the stronger vitreous charge, the lower the weaker resinous one. On a rough conductor scarcely any charge was contracted, though the plates behaved as before when separated.
From this Cigna explained why an exhausted globe or one lined with conducting matter will not excite: the vitreous electricity on the outer surface is balanced by resinous electricity in the inner coating or vacuum, and once that inner coating is removed the electricity appears outside without any fresh excitation. Ribbons laid on a smooth conductor and drawn over with a ruler all gave sparks when lifted singly and had acquired resinous electricity; lifted together they cohered as one mass, resinous on both sides. On a rough conductor, lifted singly from the lowest upward, they gave sparks and all proved vitreous except the topmost, which kept the resinous charge of friction. Two ribbons lifted together clung to each other and showed nothing until parted, when the electricity resided in the outermost, opposite to that by which they had adhered, and much weaker. Ribbons on a metal plate receiving electricity from the globe, with a pointed body held to the far side, took the opposite or the same electricity according to how they were removed—except the most remote, which always kept an opposite charge. Cigna concluded that electricity propagates from the outermost ribbon downward, or from the plate upward, exactly as when a coating is stripped from a charged pane of glass and deposits its electricity on the glass’s surface. Metal coatings without cement adhered firmly when charged and gave a light on separation; he could never strip a coated ribbon without a spark passing to the opposite coating, which fell off and discharged the whole. He thought the coatings did not surrender all their electricity, since a surface charged by friction and one charged only through the coating no longer balanced once the coating was removed, the rubbed surface prevailing. Charging a pane coated on one side while the other side drew electricity from a pointed conductor, and inverting it with the coated side against the prime conductor, he found the electricities balanced while the coating stayed; slipped off, the opposite side’s electricity prevailed and appeared on both faces.
The Leyden Phial and Its Discharges
On the phial itself, Franklin had left curious particulars, but Beccaria was first to charge other electrics: smooth sealing-wax poured on oiled marble took a considerable charge, and a mixture of pitch and colophonia charged less than sealing-wax but more than sulphur, and far more than pitch alone. Beccaria suspended a coated plate by a silk thread, charged it, and discharged it with a crooked wire approaching both sides; the plate never stirred, which proved the reaction of the glass upon the electric matter—he likened the glass to an ivory ball held between two others. Mr. Hartman of Hanover passed a shock through as many as forty cannon balls resting on drinking-glasses, all sparks appearing at one moment with a single report; with eggs the progress was visible, every two giving a separate snap and flash, best with ten or twelve. Mr. Amadeus Lullin of Geneva put a card in the circuit with the wires not opposite, and the card was pierced close to the negative wire’s end. Professor Richman of Petersburg coated both sides of a pane within two or three inches of the edge and fastened linen threads to the coatings: uncharged they hung in contact, charged they were both repelled, and a finger brought to one side made that thread fall nearer while the opposite receded; on contact it fell into contact while the opposite retreated to twice its former distance. Æpinus showed that an insulated person discharging the phial does contract electricity, and supposed Franklin’s failure came of surfaces too small and plates too near; Cigna invented a new method of charging a phial on Canton’s principle.
The Tourmalin Controversy
Æpinus repeated his experiments and still found results contrary to Wilson’s; Wilson repeated his without variation, guessing the difference lay in the size of the stones or the manner of experimenting. The narrator notes that Wilson’s apparatus was far better calculated for accuracy, and that he used a greater variety of ways of communicating heat—boiling water, candle flame, heated insulated electrics. Heating one end of a glass tube red-hot and exposing the tourmalin’s negative side to it, Wilson found about three inches of the tube electrified minus though the glass beyond was plus, and so it stayed after cooling: the fluid had passed from the stone into the glass. Applying the plus side, the tube became minus above a foot in length with no plus beyond, and the minus appeared when the tube was nearly cold, so he judged the fluid had passed from the glass to the stone. He concluded the tourmalin, like glass, is permeable to the fluid, with less resistance on the negative than the positive side; rubbing the positive side lightly made both sides plus, rubbing the negative made both plus more strongly. A line drawn from the plus part through the centre always passed through the minus part. Greasing the stone while warm weakened but did not destroy the virtue—proof, he argued, of a fixed electricity, since otherwise plus and minus would have united—and he compared it to the loadstone with two poles. Heating two in a strong fire for half an hour changed nothing, but plunging one red-hot into water destroyed its virtue entirely and left it looking shivered in many parts without breaking. A tourmalin from Dr. Morton, held between eye and light along the direction of the fluid’s passage, looked darker than at right angles.
The decisive discovery fell to Mr. Canton, in a paper read to the Royal Society in December 1759: the tourmalin emits and absorbs the electric fluid only as its heat increases or diminishes.
One Fluid or Two?
The book’s deepest running argument concerns what electricity actually is. Du Fay had spoken of two independent fluids; Watson and Franklin recast the difference between attractions and repulsions as redundancy and deficiency of a single matter. Priestley follows the single-fluid account through Franklin’s analysis of the phial — the power residing in the glass itself, not in the water or the coating — and through the charging of batteries and plates of air. But he gives Mr. Symmer’s stocking experiments full room: white and black silk, electrified positively and negatively, inflating, clinging, and requiring pounds of force to part. Symmer infers two fluids that are never independent but always co-existent and counteracting, and Priestley lets the reader weigh the case rather than closing it. The same openness governs the tourmalin, where Wilson’s careful apparatus and Æpinus’s contrary results are set side by side until Canton settles the matter: the stone emits and absorbs the fluid purely by increase or diminution of heat, and the Brazil topaz behaves the same way.
The Virtue of Small Steps
What gives the history its shape is Priestley’s conviction that knowledge advances by increments so small that contemporaries cannot see them. Grey records experiments in 1731 that he thought worth printing and that Priestley admits contain hardly anything a later reader would call new; Guericke, Boyle, and the Academicians del Cimento worked at almost the same time and, in Priestley’s judgement, drew no advantage from one another’s labours. Against this he sets the great hinge of 1745 and 1746, the Leyden phial, and the year 1752, when Franklin’s hypothesis of the identity of lightning and the electric fluid was verified in France. The narrative is punctuated by warnings as well as triumphs: the Abbé Nollet advises circumspection, and Professor Richman of Petersburg is killed at his own apparatus by a globe of blue fire drawn from the rod. Priestley reports these deaths without melodrama, as part of the record.
A Science of Amateurs and Instruments
Running beneath the chronology is a practical philosophy of how science should be done. Priestley wants philosophy subdivided, small societies formed with directors of experiments, and ships sent out for discovery of the sea and the earth. He praises Canton’s pith-ball electrometer as an exquisite contrivance, describes apparatus in enough detail that a reader could rebuild it, and treats the electrification of the air, the charging of coated panes, and the imitation of thunder and lightning as achievements of collective ingenuity — Canton, Franklin, Wilcke, and Æpinus each carrying the same principle a stage further. The book is thus a history written by a participant, and its confidence in experiment as the engine of progress is inseparable from its author’s own practice.
The Book’s Place in the Science
Priestley’s history did more than record a field; it helped constitute one. By treating electricity as a subject with a continuous past, by insisting on original sources and on the credit due to foreign as well as English workers, and by presenting experiment as a discipline open to anyone with patience and a glass tube, it gave the science a usable memory. Its later sections on atmospheric electricity, water spouts, hurricanes, and earthquakes show how far the subject’s ambitions had reached by the 1770s, and its frank accounts of the shocks and fatalities that attended lightning experiments mark it as a document of a science still dangerous to practise. For a modern reader it remains a rare thing: a history of a science written from inside the laboratory, by a man who believed the subject was only beginning.
