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Newtonian Poison

Newtonian Poison

(p.61) Chapter Four Newtonian Poison
About Method
Jutta Schickore
University of Chicago Press

Abstract and Keywords

Richard Mead’s Mechanical Account of Poisons includes a study of viper venom as well as a critical commentary on Redi and Charas. The several editions of Mead’s Mechanical Account showcase the state and dynamics of medical thought in the first half of the eighteenth century and its effect on research into poisons, and they illuminate conventions for writing, expectations for medical scholarship, and the different ways in which methods discourse could be integrated in a treatise about experimental research. For the history of methods discourse, Mead’s Mechanical Account of Poisons serves as a proof of concept. The chapter presents Mead’s work an experimentalist treatise, which contains almost no discussion of research techniques, experimental strategies, and criteria for proper procedure.

Keywords:   snake venom, methods discourse, experimentalism, mechanical philosophy, Richard Mead

Richard Mead’s work on poisons is rarely mentioned in the newer historiography of venom research. Eighteenth-century investigators of viper venom, however—notably Felice Fontana—took the chemical and microscopical analyses Mead performed seriously enough to refer to and to critique them. Mead’s work spans almost the entire first half of the eighteenth century. He published the first edition of his Mechanical Account of Poisons, which includes a study of viper venom, in 1702, very early in his professional life. Judged by the number of editions of the work, the book was a great success. Numerous editions and revisions, some of which were even pirated, appeared in the first half of the eighteenth century. In 1745, toward the end of Mead’s very distinguished career, a thoroughly revised (third) edition came out in which Mead presented a completely different account of the working of poisons, and in 1747, a fourth edition appeared (a corrected version of the third edition).

Mead was highly valued as a practicing physician and leading member of professional organizations in England. But neither his contemporaries nor indeed historians of science and medicine have greeted his written works with equal enthusiasm. Especially the latter have found nothing original in his writings and have suggested that through his books Mead mainly sought to carve out a good position for himself in the medical community. Historian William Coleman was perhaps the most impatient with Mead’s work. To him, Mead seemed not much more than Newton’s mouthpiece—“whose every gesture was to preserve vital and holy the example of this ‘Chief Philosopher’”—and a rather incompetent one at that.1 According to Coleman, Mead’s essay on poisons exemplifies “both (p.62) the obscurity and contradictions of assumed Newtonian influences in biology,” because Mead never managed to live up to the ideals to which he expressly aspired.2

There is something to this characterization of Mead and his work. The mechanical account of poisons is above all an exercise in “new medicine.” The English physician devoted only a small part of his book to viper venom; he did not conduct many experiments himself. Nevertheless, the work is instructive for my purposes. Mead’s book—more precisely, the sequence of its many editions—showcases the state and dynamics of medical thought in the first half of the eighteenth century and its effect on research into poisons. The evolution of Mead’s views reflects the general move away from mechanistic theories in medicine, the influence on medical writing (especially in England) of Newton’s Principa and Opticks, and a redirection of attention from the blood to the nerves as key functional parts of the healthy and the diseased body. Precisely because Mead was so conscious of what others required of a respectable scholar as well as of a good piece of medical writing, his text and the revisions he made to it over the years tell us something about conventions for writing, expectations for medical scholarship, and the different ways in which methods discourse could be integrated in a treatise about experimental research. In particular, the book further illuminates the broad scope of experimentalist commitments in the early modern period. As we will see, Mead was a steadfast experimentalist who performed very few experiments and had little to say about proper procedures.

An Eclectic Collection

At first glance, Mead’s professional environment was very different from the Italian context of Redi. Mead had just begun practicing medicine in Stepney, his home town (now a part of Greater London) and was trying to make a name for himself when he published his book on poisons.3 The Italian scholar was a well-respected figure who worked with a group of investigators at a scientific academy and who had ample resources at his disposal thanks to the financial means of the Florentine court. However, Mead’s work was not as remote from the late seventeenth-century Italian scene as it might seem. Mead was well acquainted with the Italian mechanistic tradition in medicine and anatomy through both his studies and his travels. He had studied the theory and practice of medicine with the avowed Newtonian Archibald Pitcairne4 in Leiden, where the Italian (p.63) tradition of mechanical anatomy and physiology was highly valued. Also, after taking his degree, Mead gained first-hand knowledge of Italian medicine, traveling extensively in Italy and even earning a medical degree at Padua. Moreover, he was well aware of the recent history of research on viper venom. In 1702, the dispute between Charas and Redi had still not been completely resolved, and Mead took it upon himself to clarify the issue under discussion. Ultimately, he sought to devise a general mechanism for the working of all poisons.5

Mead’s 1702 book is a collection of five essays on poisonous things: vipers, tarantulas and mad dogs, poisonous minerals, opium, and bad airs. In the preface, Mead noted that his original plan had been to extend this work also to include contagious diseases, but, alas! “the humour of Scibbling would not hold out.”6 Only in his later work on the plague did Mead bring together his account of poisons and his ideas about the nature of disease contagion. In fact, as I will show, the transformation of Mead’s theory of poisons parallels the transformation of his views on the nature of the plague in the early 1720s.

Mead’s book tells us how sweeping the early modern notion of experimentalism was. Mead turned against those who would argue without assistance of experiments and insisted that progress could only be made based on matters of fact. Nevertheless, for himself, experimentalism meant, above all, a commitment to selected authorities in mechanical philosophy. Mead admired Newton; he also praised the works of the mechanical philosopher Pitcairne and of Pitcairne’s close friend Lorenzo Bellini.

His main programmatic point was to try to carry the mechanical account of poisons as far as possible while at the same time grounding it in matters of fact. His expressed aim was to “Discover the Footsteps of Mechanism” in the working of poisons and to “Unravel the Springs of the several Motions” on which effects depended. He reflected that if it was possible to bring such “abstruse” phenomena under “the known Laws of Motion,” it was even more plausible that other appearances in the animal body were also due to “such Causes as are within the Reach of Geometrical Reasoning.” Knowing the cause of a disease was the first step toward its removal.7

This is experimentalism with a Newtonian flavor. Its distinctive feature is the considerable optimism about the beneficial role of mathematics for medicine. In his essay on Newton, Newtonianism, and the roles of experiment in seventeenth- and eighteenth-century scientific endeavors, Friedrich Steinle has identified three kinds of Newtonianism. Steinle distinguishes between experiments designed against the background of mathematically formulated theory (the Newtonianism of the Principia), experiments to collect (p.64) a broad set of data (the Newtonianism of the Opticks), and experiments as heuristic tools to devise hypotheses about causes (the Newtonianism of the Queries).8 Mead was a representative of the first kind of Newtonianism, the mathematization of experimental evidence. “Mathematics,” for Mead, meant “Demonstration and Truth,” and Mead laid out quite an ambitious project for medicine, expressing the hope that argumentative rigor could help transform medical practice into a science. Mathematics also served as demarcation between the professional and the quack: true physicians knew numbers, math, and geometry.

Mead’s own use of mathematics remained largely promissory. His work did not quite live up to his Newtonian aspirations, as he himself modestly admitted and as many historians have been keen to point out. Mead’s book is a rather eclectic mixture of ideas associated with mechanistic anatomy, medicine, and chemistry. Each of the essays in the book describes symptoms of poisoning and considers remedies, and each includes a more or less detailed explanation of the working of the respective poison. There are some common and recurrent features in these explanations: the poisons are generally described as acting on the blood and obstructing its circulation, the action is regarded as a process of fermentation, and Mead assumed that the properties of the particles contained in the poisons damaged the internal fabric of the body mechanically (through pricking and tearing).

The essay on viper venom opens the collection. Mead aligned himself with Redi’s view that the yellow liquor caused the symptoms following the bite. He did note that symptoms of poisoning might be more or less severe depending on the circumstances, such as the climate, the season, the size of the snake, and the snake’s greater or lesser rage; but usually the nature of the symptoms would be the same in every bite.

The essay offers assorted insights from microscopy, chemical testing, and animal experimentation to support the idea that viper venom works by mechanical operation. Mead announced that his account was based on matters of fact, but he did not hide from his readers that those facts had mostly been provided by others. He had not seen everything with his own eyes. He treated other peoples’ findings as trustworthy even though it was “far more easie to Spin out a false Notion into precarious Reasonings, than to make faithful experiments.”9 As commentators then and now have noted, Mead himself was pretty daring in his own reasoning as he pieced together hypotheses and explanations from various sources. What is remarkable is not Mead’s warning about precarious reasonings and the spinning out of false notions but rather that Mead told his readers very little about how to (p.65) make faithful experiments. Unlike Redi’s and Charas’s extensive empirical investigations, Mead’s own practical work appears to have been confined to some microscopical observation and chemical testing and a few experiments. Mead told his readers what he had found, but not much about how exactly he had proceeded. We learn that he managed to extract drops of liquid from a viper’s fangs by letting it bite on something solid. He then put the drops under the microscope. What he saw under the microscope very much suggested a mechanical operation of the venom. He found at first “a Parcel of small Salts nimbly floating in the Liquor, but in a very short time the Appearance was changed, and these saline Particles were now shot out as it were into Crystals of an incredible Tenuity and Sharpness, with something like Knots here and there, from which they seemed to proceed, so that the whole Texture did in a manner represent a Spider’s Webb, tho’ infinitely Finer, and more Minute; and yet, withal so rigid were these pellucid Spicula, or Darts, that they remained unaltered upon my Glass for several Months.”10 Quite possibly, particles like these could damage the internal fabric of the body through pricking and tearing.

To determine the chemical nature of the fluid, Mead made use of the by then well-established indicator test. Despite the difficulty and hazard involved in experimenting with such a small quantity of such a dangerous substance as viper venom, he had “plainly seen that it does, as an Acid, turn the Blue Tincture of Heliotropium to a Red Colour.” Mixing the venom with syrup of violets did not give quite as clear results, but “it did really seem to induce in this a Reddish Hue.” In any case, Mead was certain it did “not at all change it to a Greenish Colour, as it would have done if any ways Alcalions.”11

When Mead commented on the controversy between Redi and Charas, he did mention experimental procedures, but his comments remained fairly general and conjectural. He sided with Redi. The notion that the force through which the venom was thrust into the blood determined the venom’s efficacy explained why some experiments with viper venom did not succeed in killing the animal and also why there was a discrepancy between Charas’s and Redi’s experiments. Charas might simply not have been forceful enough in administering the venom; hence the venom was not active enough to affect the blood in a fatal way. Mead suggested that prejudices might have played a role in shaping the experimental outcome: Charas’s timidity might have been due to his theoretical commitments, “in as much as there is oftentimes a great deal of difference in the Event of Experiments, when made with Purpose, and a Design that they should (p.66) Succeed, and when Timorously and Cautiously managed, lest they should unluckily overthrow a darling Hypothesis.”12

Mead did not attempt to repeat any of the experiments himself; instead he relied on the results of three animal experiments his friend Dr. Areskine had made in Paris, expressly “in order to put this Matter out of all doubt.”13 There was nothing innovative in the design or performance of these experiments. In the first series, six pigeons were bitten by a live viper one after another. The first three animals died, the fourth recovered, and the last two did not show any sign of great inconvenience. In the second experiment, two pigeons died, having been wounded by the head of a dead viper. In the third experiment, two pigeons received previously collected yellow liquor through wounds. Both died within two hours. All this agreed very nicely with Redi’s claims that the yellow liquor was poisonous when introduced into the blood through wounds and that it was used up during the first two or three bites. Mead reported that according to his friend Areskine, another French gentleman, du Verney at the Académie, had made “not only These, but also several other Experiments of the same Nature” with similar success.14 Mead merely stated that the proofs were so convincing that no further experiments were necessary—besides, he said, the viper’s mouth was obviously designed for the purpose of discharging venom.

The essay ends with a brief discussion of therapeutics, and only in this context did Mead make one brief comment that was related to concrete methods and procedures. Mead considered possible remedies for snakebite, such as sucking the wound and the application of snake stones, as well as the merits of viper meat as a remedy for certain illnesses. In both cases, “faithful experimentation” was presupposed. Mead’s aim was to show that assumptions about the physical properties of spiky salts had explanatory power. Sucking bite wounds was obviously effective because it prevented the salts of the venom from harming the blood. Because snake stones had a spongy and porous texture, they could, to an extent, also extract the salts from the wound, but they did not do so very effectively. This explained the mixed results of trials with snake stones as remedies (so, again, faithful experimentation was presupposed). Only when Mead turned to an assessment of a certain specific that viper catchers were using—apparently with great success—did he refer to an actual experiment. He found that the specific was Axungia viperiana—the soft fat of the viper’s body—which, rubbed into the bite, immediately cured the person bitten. To examine its effects, he had a young dog bitten in the nose and treated the wound with Axungia. The dog recovered and was well the following day, so the treatment must have been effective.

(p.67) In light of the great emphasis that Redi had placed on “many many” repetitions it is noteworthy that Mead initially seemed to have considered one single trial sufficiently demonstrative. His methodological interests did not extend to the particulars of proper experimental procedures. Apparently only because some of the gentlemen who witnessed the trial were not quite convinced of its demonstrative powers, Mead saw the need to continue. His critics did not take issue with the experiment itself; they objected that other explanations could not be ruled out. The recovery might have been due to the dog’s spittle rather than the viper fat. Mead had the dog bitten again, this time in the tongue, and no Axungia was given. The dog died within four or five hours, so its spittle could not have done much good.15 Mead added that he had successfully repeated this trial (just once).

Mead’s own main contribution to the debate was an explanation of the way in which the venom worked—mechanically, of course. Mead was able to explain the interaction between the spiky crystals and the blood as fermentation. The explanation is rather convoluted, combining reports of experiments Mead had garnered from the Philosophical Transactions with an assortment of ideas about fermentation, acid–alkali mixtures, and the nature of blood. To put together this explanation, Mead helped himself liberally to ideas presented in the main works of Boyle, Pitcairne, Bellini, Bernoulli, and others.

The notion of and interest in fermentation had a long tradition in chemistry, reaching back to Paracelsus. In the late seventeenth century, it had become a label for a wide range of natural processes, including the formation of winds, the germination, flowering, and decay of plants, and the heat of the blood.16 Toward the end of the seventeenth century, different conceptions of fermentation took shape, and the notion of fermentation also became part of the chemistry of acids and alkalis.17

In an article published in the Philosophical Transactions, Edward Tyson had already described the fermentation produced by the mixing of coagulated human blood with cobra venom. Mead referred to Boyle’s and Pitcairne’s claims that there was nothing of acid in human blood and that arterial blood was an alkali. When mixed with venom, arterial fluids thus exhibited the characteristic phenomena of acid–alkali mixtures “according to the known Principles of Chymistry”—so Mead assumed.18 In the first step of the argument, Mead used the concept of fermentation in a general sense to refer to changes of fluids. Following Bellini’s theory of disease [De Stimulis], Mead explained that the spikes of the pungent salts of the venom, when mixed with the blood, would change the cohesion of the globules, thereby affecting the degree of fluidity and impulse of the (p.68) parts so that the “very Nature [of the blood] will be changed, or in the common way of speaking, it will be truly and really Fermented.”19

Mead then relied on Bellini [De Fermentis] and especially to Newton’s Principia to explain in general terms the nature of fluids: In all fluids, there is not only contact between the parts but also cohesion or—as Newton had demonstrated—attraction. If the cohesion of the parts was changed, “an Alteration of the Nature of the Fluid” occurred—that is, a process of fermentation “as the Chymists express it.”20 Mead then advocated a version of the mechanical interpretation of fermentation as a change in the physical properties of parts that Bernoulli had expounded in his 1690 book Dissertation on Effervescence and Fermentation. In it, Bernoulli spoke out against an occult quality as the cause of these processes. He explained these processes in mechanical terms as the result of an action of a sharp body on another body, through which the body acted on was destroyed and the air contained in it was expelled.21 Mead borrowed from Bernoulli to explain the process of fermentation in mechanical terms as an outcome of the mechanical properties of the salt of the venom. The blood fermented because the acute salts pricked the globules of blood, thereby destroying the walls of the globules. This freed the active substance imprisoned in the globule, and the fluid thus discharged served as a vehicle to disperse the venom. When the “acute Salts” mingled with blood globules, which contained a very subtle fluid, they changed the cohesion of the blood corpuscles. They “do prick those Globules, or Vesiculae, and so let out their imprisoned active Substance, which expanding it self in every way, must necessarily be the Instrument of this speedy Alteration and Change.”22

Like Charas, Mead let the explanatory power of his account speak for itself. This happy mixture of ideas could explain many features of the effects of snake bites. Above all, his approach could account for one puzzling factor—namely, the speed with which a small portion of venom could swiftly affect the entire body. The spikes of the salts pierced the blood globules, and the active substance that was thus freed served as a vehicle to disperse the salts all over the body. At the same time, the fermentation of the blood disturbed the circulation, interrupted the secretion of the spirits, and obstructed the flow of the bile (thus producing jaundice). The changes of the blood then affected the fluid of the nerves, which caused nervous complaints like convulsions and sickness.

Mead also claimed that the force through which the venom was inserted into the blood mattered to the efficacy of the venom. This means that experiments did not completely mimic the process of viper poisoning, because the bite of the viper was more forceful than the experimental (p.69) procedure of first making a wound and then instilling the venom. He did not draw any further conclusions regarding the epistemic force of experiments but simply presented his theory as a guideline in the search for an antidote: its nature had to be such that it could overcome the venomous ferment. Later in the text, Mead noted that chemical theory could explain why poison taken by mouth was ineffective: the action of the stomach turned acid substances into alkaline ones, thereby breaking their spikes and thus rendering them harmless.

Early modern scholars expressed different views about how to combine empirical data and theory: Redi put forward an argument about causes but refrained from discussing possible explanations for the working of venom. Charas advanced an explanation and showed how much he could explain with it. Mead took the same approach, and he also had some explicit comments on the issue. On the one hand, he was not altogether against hypotheses. He found hypotheses acceptable if they could explain the phenomena. He noted, for instance, that his mechanical concept of venom could account for many features of the effects of snake bites—indeed, (so Mead claimed) better than other theories did. “From such an Hypothesis as this,” he noted, “(and, it may be, not very easily from any other) we may account for many of the surprising Phaenomena in the Fermentations of Liquors; and as precarious as it seems, its Simplicity, and Plainness, and Agreement with the forementioned Doctrine [Bernoulli’s mechanical theory of disease], will, I believe, recommend it before any other to those who are not unacquainted with Geometrical Reasonings.”23 Newton, of course, had argued that hypotheses or conjectures had no place in natural philosophy proper, even though they might be entertained for heuristic purposes.

Historians of science have chided Mead for seeing “no incongruity between full liberty in casting hypotheses on a most ad hoc basis and claiming that his hypotheses enjoy the protection of mathematical vigor. His remarkable statement to this effect betrays the logical infelicities of prominent elements in a so-called Newtonianism.”24 Anita Guerrini even maintains that the ambitious young doctor referred to Newton solely to gain social capital. She doubts that Mead ever read the Principia.25 Although it is correct that despite his avowed Newtonianism Mead made no attempt at meeting Newton’s concrete methodological requirements for meticulous inductive reasoning, and that his arguments do not appear very rigorous to the modern reader, his explicit emphasis on these matters surely helped make Newtonianism a plausible option as a programmatic commitment and as a style of reasoning from experiments.

(p.70) Newtonian Bodies

Mead published the first edition of the Mechanical Account of Poisons at the very beginning of his career. In the years following its publication, he quickly became an influential member of the medical community in England. He was elected to the Royal Society in 1703 and to the College of Physicians in 1709, after Oxford had recognized his M.D. from Padua. Having moved to London, he became one of the governors of St Thomas’s Hospital, and he was also instrumental in the founding of Guy’s Hospital. Mead was personally acquainted with many luminaries of his time, including George II and Newton, whom he attended during the latter’s last days of illness.

In the mid-1740s, when the third and fourth editions of his book on poisons were published in quick succession, Mead could look back on a long and distinguished career as physician and a somewhat less distinguished but certainly prolific career as medical author. Perhaps his most popular work was a treatise on the plague, first published in 1720 (just after the arrival of the plague in Marseilles, in 1719). The book went through six editions during that year, and several more followed; it was translated into Latin, Dutch, and Italian. Besides the book on the plague, Mead also published treatises on the sun’s and moon’s influences on the animal body, on diseases mentioned in the Bible, and on smallpox and measles.26 But it was his discourse on the plague that proved momentous for the development of his work on poisons. Only then did his book on poison become more than just a collection of facts and hypotheses about poisonous things: it now became an account of the operation of poison that was informed by Mead’s own thoughts on disease. Still, the product remained eclectic; Mead did not fully reconceptualize the work. Instead he inserted new sections, which sit somewhat awkwardly with the remnants of the original edition. Newton still loomed large, but Mead now relied on Newton’s matter theory—the matter theory from the Opticks—rather than on the methodological rules from the Principia. Newton’s theory of ether now did the explanatory work that the mechanical philosophies had done in the 1702 edition. This new orientation had some consequences for the Mechanical Account.

The most remarkable feature of the two works is how intricately they are intertwined. Both books developed from tools intended to promote Newtonianism and mechanical philosophy (and Mead) into actual contributions to medical scholarship. Both, however, drew largely on empirical evidence and theoretical concepts provided by people other than Mead.

(p.71) Mead thoroughly revised the discourse on the plague in the early 1720s; the resulting eighth edition appeared in 1722. In the 1740s, after retiring from his professional duties, he took the time to revise some of his earlier works, including (yet again) the discourse on the plague and the account of poisons. The ninth edition of the former, which contained additional changes, was published in 1744; a revised edition of the latter appeared shortly afterward. The treatise on the plague presented the affliction as a contagious disease caused by a poison, the plague contagion.27 One of the major innovations in Mead’s account of the plague appeared already in the revised eighth edition of 1722. It was a reference to Newton’s matter theory as drawn from the Opticks. This work became the new point of orientation for Mead’s thought on disease. Toward the end of the chapter on the origin and nature of poisons, Mead briefly considered the cause of the disease. Until the eighth edition, the plague is assumed to work mechanically, like the viper venom, just as Mead had described it in the 1702 collection of essays on poisons: the plague contagion affected the blood and body fluids by giving them “corrosive Qualities” that in turn produced inflammation and gangrene.28 Referring to Queries 18–24 of Newton’s Opticks, in which Newton had outlined his ether theory, Mead also surmised that this process could be subsumed to the laws of interaction between particles and that the operation of the plague contagion somehow depended on a “subtile and elastic Spirit diffused throughout the Universe.”29 But he added that Newton had not explained in detail the operations of this spirit, so the exact nature of these operations remained unclear.

In the ninth edition, published in 1744, Mead developed the brief reference to Newton and extended it to a more comprehensive theory of the working of the plague contagion. The section moved to the next chapter, titled “On the cause of disease.” Mead now assumed that the contagion affected the nerves first. But he still relied on Newton to explain this process. Mead drew attention to two phenomena that a theory of poisons had to explain. One was the nature of the symptoms, which were for the most part nervous complaints: “rigours, tremblings, heart-sickness, vomitings, giddiness, and heaviness of the head, an universal languor and inquitude, the pulse low and unequal.”30 The other was the considerable speed with which the poison acted.

Renouncing his own previous position, he now stated that the blood could not become corrupted quickly enough for the symptoms to be caused by it. Drawing on Newton’s Opticks, Mead argued that the nature and suddenness of the effects of the disease “must be owing to the action of some (p.72) corpuscles of great force insinuated into, and changing the properties of, another subtile and active fluid in the body; and such an one, no doubt, is the nervous liquor.”31 Mead again compared this fluid with Newton’s ubiquitous subtle and elastic fluid. Taking a cue from Newton’s Query 24, he assumed that the nerve fluid, the animal spirits, somehow incorporated much of this elastic fluid, which thus possessed great energy and was very susceptible to alteration. In keeping with some elements of his earlier account, he used chemical concepts to explain that the mixing of the contagion and the nervous fluid could be regarded as the fermentation that occurred between two “chymical spirits” when they were put together.32

The new edition of Mead’s essays on poisons appeared shortly after the ninth edition of the discourse on the plague. The new version of the work drew heavily on Mead’s discourse on the plague. It still contained the old preface, but it was framed by a six-page advertisement, in which Mead explained some of the changes he had made, and by a new introduction. He made light of his change of opinion: “Dies diem docet. I think truth never comes so well recommended as from one who owns his error.”33 Perhaps the most significant change was that the new introduction now offered the general account of the working of poisonous substances that the first edition had lacked. Main passages of it are cribbed nearly verbatim from the 1744 discourse on the plague. Mead explicitly referred to the discourse to reconfirm that all he said about animal, vegetable, and mineral poisons applied to disease contagion and vice versa. Poisons did not affect primarily the blood; they harmed the fluid of the nerves first. Mead still suggested that one of the effects of poison on the animal body was an alteration of the blood, but he now proposed that this was a secondary effect. The vitiated nervous fluid would cause irregular circulation, interrupted secretions, and stagnation of the blood, which would then produce additional ill effects in the body of the victim. Only the flow, not the nature of the blood, would be changed.

In the first edition of the Mechanical Account, Mead relied on matters of fact as they were provided by others. The fourth edition is quite remarkable for how Mead combined “old” evidence with the new theoretical perspective and some new facts. As before, he relied mostly on the reports of others. His contribution was limited to providing an account that made sense of the evidence available.

The main reasons for adopting a new account of the working of poison were the same as the ones Mead gave in the discourse on the plague: the rapidity with which the poison worked and that the symptoms of poisoning were all nervous complaints. Mead added two pieces of pertinent empirical (p.73) information, again provided by others. One stemmed from an article published in the Philosophical Transactions of 1727–28 whose author reported that the bite of a rattlesnake had killed a dog in less than fifteen seconds. The other came from James Keill’s 1718 measurements of the velocity of bloodflow. These measurements indicated that the blood circulated much too slowly to account for the speed with which the poison took effect.

Like in the discourse on the plague, Mead assumed the presence of animal spirits or nervous fluid in the nerves. Once more referring to Queries 23–24 from Newton’s Opticks as well as to a letter from Newton to Boyle, written in 1678 and published in the 1740s, Mead repeated his statement that animal spirits were something substantial—a thin, volatile liquor of great force and elasticity and a part of the universal elastic matter. The nervous fluid—quick, active, forceful, and capable of receiving alterations from other bodies—was the medium through which poisons worked in the animal body. Due to the speed and great activity of the nervous fluid, poisons could immediately affect and disturb the entire animal economy, thus producing the violent spasms, pains, palpitations, and other symptoms of poisoning. Mead retained the notion of fermentation to explain the working of poisons. The actual interaction between the poison and the (nervous) fluid is likened to fermentation of chemical liquors, whereby fermentation is now explained as “indeed no more than the attraction and repulsion of the particles of different bodies, when they come together.”34 This account applied to all cases of poisoning, including the bite of a mad dog, the intake of opium, and the inhalation of bad air. In the essay on vipers, Mead merely referred the reader to the general explanation presented in the introduction.

The first edition of the mechanical account of poisons marshaled empirical data specifically to support Mead’s initial theory of the working of the venom. In the later edition, the passages on microscopical observations of spiky crystals are left unchanged. Nothing follows from them. The chemical–mechanical discussion of salts and fermentation is omitted from the new edition. The great activity and force of the nervous fluid and its potential for being affected by other forces is now crucial. The reports on chemical tests with the venom differ significantly from the earlier account: Mead reported new tests performed on a mixture of human blood and viper venom. The first edition of the essay, by contrast, describes results obtained from indicator tests with undiluted venom, which showed that the venom was an acid. The fourth edition reports pairs of tests: Each test was performed twice, once on the mixture of blood and venom and once on plain blood. Both liquids looked the same after the venom had (p.74) been added to one. When the tests with heliotropium and syrup of violet were performed, no alterations were visible, and no fermentation or change of color occurred; the mixture thus did not exhibit the characteristics of acid–alkali mixtures that Mead had observed in his first book. In all experiments, the mixture behaved just like plain blood. Neither spirit of niter nor salt, tartar, or lemon juice produced any fermentation or change of color in the fluids.35 Mead did not explicitly tell his readers what to make of these experiments, but one may assume that the tests were meant to support his claim that the venom did not affect the blood. If it did not, then the ill effects could well be caused by a change of the nervous fluid.

The revised edition mentions again the animal experiments Areskine and du Verney had performed in Paris. In addition, it reports new experiments that Mead and his colleagues had carried out “with a view to the controversy between Signor Redi in Italy, and Monsieur Charas in France.”36 More than fifty years after that controversy had taken place, it was still significant enough for Mead to engage with it. The experiments seem to have been similar to those earlier ones performed by Redi himself. Mead still did not discuss any methodological issues concerning experimentation, and he left to his readers the interpretation of the evidence.

The first series of experiments, in which “several animals, dogs, cats and pigeons” were bitten by an enraged viper and “generally died, some in a longer, others in a shorter space of time,” seem to have been performed to demonstrate the nature of the symptoms of poisoning. Mead reported that it was constantly observed that all animals were affected by “sickness, faintings, convulsions, etc.”37 These are best explained as nervous afflictions.

One pigeon was wounded in the breast by the head of a viper three hours after the head had been cut off. The bird died as if from the bite of the live snake, and one may conclude that Mead took this as evidence to support the claim that the yellow liquor was the poisonous part of the snake and that the anger of the viper was not essential for the poisoning. Finally, Mead and his colleagues had a sharp hollow steel needle made, “in shape not unlike to the Viper’s tooth,” into which they put a drop of venom and wounded the nose of a young dog. This animal recovered. But a pigeon wounded in the breast with the same needle “suffered as from the bite, and died in about eight hours.”38 Confronted with the discrepant outcomes of the experiment, Mead merely inserted his comment from the first edition that “there is a great deal of difference in the success of the same experiments, when faithfully and judiciously made, and when (p.75) they are cautiously and timorously managed, lest they should happen to overthrow a darling hypothesis.”39

Having thus warned the reader once again of the danger of prejudice in experimentation, Mead reported the last experiment he and his colleagues had performed: they had tasted the spiky salts. None of the men suffered any ill effects from the tasting, but all agreed that it tasted “very sharp and fiery, as if the tongue had been struck with something scalding or burning.”40 As before, Mead’s concern was to offer an explanation that fit the facts that he had assembled. The saline spikes were broken up in the mouth and in their passage through the digestive tract so that they could not do any harm. Together with the chemical investigation of the mixture of poison and blood, these experiments and assumptions supported—or at any rate did not contradict—Mead’s notion that the venom acted on the nervous fluid.

Writing Mechanically

Mead’s mid-eighteenth-century biographer (who, by the way, did not refer to the link between Mead’s works on poisons and on the plague) approved of Mead’s conversion, noting, “In his younger days he imagined he was able to account mechanically for the effects of several poisons, by their mixture with blood; but when he was improved by age and experience, he was fully convinced that there is, in all living creatures, a vehicle infinitely more subtil, an ethereal and invisible liquor, over which poisons have a real tho’ inexplicable power. Such is the progress of science.”41 This author saw in Mead’s conversion chiefly a laudable move away from the old mechanical philosophy.

Indeed, the different editions of Mead’s treatise echoed the developments of medicine and matter theory in the eighteenth century. The transformation of Mead’s views between 1702 and 1745 was obviously driven not by any new experiments Mead had performed but rather by the encounter with Newton’s Opticks, by Mead’s wish to promote Newtonian thought, and by the redirection of medical attention from the blood to the nerves.

Chapters 2 and 3 have shown that both Redi and Charas were expressly concerned with the methodological aspects of experimentation and that methods discourse was shaped, in part, by practical problems of experimentation. Mead expressed a commitment to “matters of fact” and to (p.76) experimentation as the final arbiter of truth, but apart from that, we find only an occasional warning against the dangers of prejudice—nothing comparable to the detailed methodological discussions one finds in Redi’s and Boyle’s texts or even in Charas’s work. What little discussion of methods and methodologies is in Mead’s treatise does not seem to be informed by any practical challenges he might have encountered in his research. Mead advocated “Newtonian” experimentalism, but his commitment to the “mathematical ideal” from the preface of the first edition—which is included in the text of the third and fourth—appears to be even more perfunctory in the later editions. The arguments and explanations offered in both versions of the text are not organized tightly and do not refer to numbers, math, and geometry as one would expect from someone who subscribed to a mathematical ideal, nor are the experiments designed against the background of a mathematical theory.

Much of the evidence of the 1702 text—notably the results from animal experiments and the microscopical observations—appears again in the later edition but in support of a different theoretical explanation of the modus operandi of the venom. The microscopical observations of the spikes of the salt reappear unchanged in the third edition, and there is no indication that Mead had repeated them. They no longer play a key explanatory role. They might have been used to explain the pungent taste of viper venom, but this was not how Mead used them; the tasting of the venom did not play any part in the argument of the later edition. The evidence from the chemical tests in the 1745 essay flatly contradicts the outcomes of the indicator tests in the earlier essay. But Mead did not address this point; he just remained silent about the chemical nature of the venom.

For the history of methods discourse, Mead’s Mechanical Account of Poisons serves as a proof of concept. It helps us read Mead’s Mechanical Account as an experimentalist treatise even though it contains almost no discussion of research techniques, experimental strategies, and criteria for proper procedure. Distinguishing among different layers of methods discourse helps capture the continuities and discontinuities between conceptualizations of proper procedure across historical periods.


(1.) W. Coleman, “Mechanical Philosophy and Hypothetical Physiology,” in The Annus Mirabilis of Sir Isaac Newton, 1666–1966, ed. Robert Palter (Cambridge, MA: MIT Press, 1970), 323.

(2.) Ibid., 325.

(3.) For biographical information about Mead, see Richard H. Meade, In the Sunshine of Life; a Biography of Dr. Richard Mead, 1673–1754 (Philadelphia, PA: Dorrance, 1974); and Matthew Matty, Authentic Memoirs of the Life of Richard Mead, M.D. (London: Printed for J. Whiston, and B. White in Fleet-Street, 1755).

(4.) Anita Guerrini, “Archibald Pitcairne and Newtonian Medicine,” Medical History 31 (1987): 70–83.

(5.) Arnold Zuckerman, Dr. Richard Mead (1673–1754): A Biographical Study (PhD diss., University of Illinois, 1965), 33.

(p.245) (6.) Richard Mead, A Mechanical Account of Poisons (London: 1702), preface, n.p.

(7.) Ibid., preface, n.p.

(8.) Friedrich Steinle, “Newton, Newtonianism, and the Roles of Experiment,” in The Reception of Isaac Newton in Europe, ed. Helmut Pulte and Scott Mandelbrote (Continuum Publishing Corporation, forthcoming).

(10.) Ibid., 11

(11.) Ibid., 10.

(12.) Ibid., 17.

(13.) Ibid., 22.

(14.) Ibid., 23.

(15.) Ibid., 29–30.

(16.) One of the most enthusiastic advocates of such an all-encompassing notion of fermentation was the Oxford physiologist Thomas Willis; see Allen G. Debus, “Rise and Fall of Chemical Physiology in the Seventeenth Century,” Memorias da Academia das Ciencias de Lisboa, (Classe de Ciencias) 36 (1996): 40; and Ku-Ming (Kevin) Chang, “Fermentation, Phlogiston and Matter Theory: Chemistry and Natural Philosophy in Georg Ernst Stahl’s ‘Zymotechnia Fundamentalis,’” Early Science and Medicine 7 (2002): 33–35. Highlighting the widespread concern with fermentation in the second half of the seventeenth century, Kevin Chang even speaks of a “fermentational program” (33–37).

(19.) Ibid., 13.

(20.) Ibid., 15.

(21.) Johann Bernoulli, “Dissertation on the Mechanics of Effervescence and Fermentation,” Transactions of the American Philosophical Society 87 (1997): 55.

(23.) Ibid., 15–16.

(25.) Anita Guerrini, “Ether Madness: Newtonianism, Religion, and Insanity in Eighteenth-Century England,” in Action and Reaction: Proceedings of a Symposion to Commemorate the Tercenary of Newton’s Principia, ed. Paul Theerman and Adele Seeff (London: Associated University Presses, 1993), 236.

(26.) With this work, Mead became entangled in a vicious controversy between his close friend John Freind and the Oxford physician John Woodward about the use of purgatives in the treatment of smallpox.

(p.246) (27.) Arnold Zuckerman, “Plague and Contagionism in Eighteenth-Century England: The Role of Richard Mead,” Bulletin of the History of Medicine 78 (2004): 273–308.

(28.) Richard Mead, A Short Discourse Concerning Pestilential Contagion, 8th ed. (London: 1722), 38.

(29.) Ibid., 39.

(30.) Mead, A Short Discourse Concerning Pestilential Contagion, 9th ed. (London: 1744), 48.

(31.) Ibid., 48.

(32.) Ibid., 50.

(33.) Mead, A Mechanical Account of Poisons, 4th ed. (London: J. Brindley, 1745), iv–v.

(34.) Ibid., xxxvii.

(35.) Ibid., 16–18.

(36.) Ibid., 20.

(37.) Ibid., 18.

(38.) Ibid., 19–20.

(39.) Ibid., 21.

(40.) Ibid., 22.

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