When Cavendish studied factitious air in 1766, phlogiston
In this chapter we are concerned with the main components of common air
As Cavendish had noted in his 1766 paper on factitious air, in a major paper in the Philosophical Transactions in 1772 Priestley
Upon combining different kinds of air, chemists observed a large change in volume, the basic understanding of which came about only at the very end of Cavendish’s life. To look ahead, in 1809 Joseph Louis Gay-Lussac
Priestley’s work on airs in turn stimulated Cavendish to return to the subject, at first in connection with Priestley’s nitrous air
|Infl. Air||Common Air||Effects|
|1||9||Fired with difficulty, little noise|
|2||8||Fired easily, moderately loud|
|8||2||Burned without notice|
With a desire to improve on the method of loudness, Cavendish invented a mechanical apparatus to measure the strength of detonation of inflammable air with other airs, the pressure lifting a pivoted board to different heights.13 Given his interest in the composition of the atmosphere, he welcomed the new instrument, the chemical eudiometer, for determining the breathable portion of air. In 1783, he published a paper on a “new eudiometer,” which he began: “Dr. Priestley’s discovery of a method of determining the degree of phlogistication of air by means of nitrous air, has occasioned many instruments to be contrived.…”
An example shows how carefully Cavendish investigated the working of a eudiometer He wanted to know if any fixed air was produced by mixing common and nitrous airs. Before mixing them, he washed both airs with lime water to remove any fixed air that might already be present as an impurity. He then combined the two airs in a bottle inverted in a vessel of lime water, which he had filtered through paper to make certain it was clean, and set it by for a day. He observed no clouds or sediments “in the smallest degree,” which if present would have indicated fixed air. To make certain that the lime water was effective and not saturated by dissolved fixed air, he breathed through it, observing clouds formed from the fixed air in his breath. “Lest it might be supposed” that the clouds in the lime water were owing to a volatile alkali in his breath, he breathed the same way through distilled water” to which he had added a reagent, finding that no clouds were formed.16 This test of a test of a test shows Cavendish’s circumspect awareness of experimental deception.
Because the eudiometer was a measuring instrument, Cavendish defined a set of quantitative terms to use with it. He called a bottle of a size that held 282 grains of water one “measure
Once he was assured that his eudiometer gave consistant readings, Cavendish applied it to a question of interest at the time, the constancy or variability of the atmosphere
14.1 Eudiometer. Figure 1 shows the main apparatus, a glass cylinder A with brass cap and a cock at the top and an open brass cap at the bottom fitted into a socket of a bent brass holder as “a bayonet is on a musket.” The whole is submerged in a tub of water. Figure 2 is an inverted bottle for holding air, and Figure 3 is a standard measure of air. Cavendish’s method
14.2 Eudiometer. The metal eudiometer belonging to Cavendish was presented by Humphry Davy to the Royal Institution, where the authors took this photograph. The instrument is about 6 inches long and 2 inches across. The stop-cock on the top served to fill and exhaust the cylinder, the one on the bottom to remove the water resulting from explosions of airs in the cylinder. Reproduced by permission of the Royal Institution of Great Britain.
14.3 Standard Volume Measures for Air
Cavallo accepted Fontana’s conclusions about the purity of air in different places and at different times, and also about its irrelevance to problems of health, “but the essential part seems to be still in the dark; it is therefore requisite that philosophical people, in various parts of the world, would make as many and as various experiments, concerning the purity of the air at different times […] in order to investigate the laws of those changes; which study is perhaps the most interesting part of the study of elastic fluids.”20 Cavendish made the experiments that Cavallo wanted, though his finding was not what Cavallo expected.
With his new eudiometer, Cavendish measured air taken in London and in Kensington under variable conditions
To judge by the results he obtained with it, Cavendish’s improved eudiometer was very good. Several years after his paper, Blagden
At the end of his paper on the eudiometer, Cavendish compared its action with the sense
Around the time that Cavendish measured the composition of the atmosphere, it became a medium of human transport. The balloon was invented, and with it a new kind of adventurer came onto the scene, the “aeronaut.” Balloons
Cavendish was regarded as a founding father of balloon flight. From his description of inflammable air
“Practical” flying was a French specialty. The relevant chronology of events is as follows. In 1782 the French brothers Joseph
Interested in the science of flight,34 Cavendish was naturally interested in balloons from the start. When balloons appeared in the skies above England, Cavendish and his colleagues came out in force to observe them. From the top of Aubert’s house at Austin Friar’s, Cavendish and Blagden made observations of Lunardi’s balloon every one or two minutes for above an hour. From a house on Putney Heath the next month, Cavendish and Dalrymple observed the balloon carrying Blanchard and Sheldon. Using a different method than the others, taking altitudes only, Cavendish calculated the height of the balloon as 3000 feet.35
Cavendish was not attracted to the adventure of balloon flight, and he did not go up in one, but he was interested in what he could learn from them. Through Blagden, he enlisted Jeffries to sample the air during his flight with Blanchard
The inflammable-air balloon was fully understood on the basis of weight, but the hot-air balloon raised a question. To decide if hot air alone caused the balloon to rise or if the balloon also depended on a substance lighter than common air
Balloons fulfilled an age-old dream of flight, creating a sensation in France and mixed feelings in Britain. Not without a touch of envy, the British spoke of “Balloon madness” or else of missed opportunity. Banks said that it was to be hoped that the English would “not rise to the absurd height we have seen in France.”40 Blagden regarded Sheldon
In 1784 Cavendish
Observed to occur in many chemical processes
The immediate occasion of his new research was experiments carried out by Priestley and his colleague John Warltire
We might expect that just as he and Joseph Black had replaced the ancient element air with distinct gases, he would announce that the ancient element water is a combination of airs, but it is uncertain if that is what he thought his experiments showed. He concluded that dephlogisticated air
Exactly what importance Cavendish attributed to the nature of water we probably can never know with certainty. The object of his experiments was to find the cause of the diminution of air by all the ways it can be phlogisticated, and the production of water gave him his answer. It was the kind of answer scientists like, a single cause for an effect brought about
by different agencies, and the cause in this instance did not depend on deciding the nature of water. In arriving at his answer, Cavendish relaxed another standard of his, caution
What Cavendish thought he did in his experiments on air was important to Wilson because of the rival claims in the water controversy. The interpretation that mattered to chemistry was Lavoisier’s
Following his conclusion that dephlogisticated air is water deprived of phlogiston and that inflammable air
In his paper of 1784 Cavendish said that he found no role for fixed air in the various instances of phlogistication of common air
14.4 Apparatus for Experiments on Air. For converting phlogisticated air
Much of Cavendish’s paper of 1784 is taken up with a related question, the source of acidity of some of the dew. To further examine it, he repeated his experiments using a large glass globe; he found that when he substituted dephlogisticated air
The next year, 1785, Cavendish published a second paper under the same title, “Experiments on Air.” In the first paper he said that an electric spark
Word of Cavendish’s new experiments traveled quickly. Two weeks after his paper was read to the Royal Society, Blagden
In the course of his experiments, Cavendish had discovered nitrites and nitrates, which drew considerable interest and puzzlement. Lavoisier
Cavendish’s contributions to pneumatic chemistry
Daniel Rutherford, Black’s and Cullen’s student, wrote his medical dissertation in 1772 at the University of Edinburgh on Black’s fixed air or, as Rutherford called it, “mephitic air.” In the course of his experiments, Rutherford
In his paper of 1785, Cavendish said that little was known about the “phlogisticated part of our atmosphere,”
If Cavendish’s later work is looked upon as a kind of chemical meteorology, it takes on an additional significance. The title he gave to his two chemical papers in 1784 and 1785, “Experiments on Air,” referred to common air, the air of the atmosphere, a mix of dephlogisticated and phlogisticated airs. Cavendish intended the first paper to “throw great light on the Constitution and Manner of production of dephlogisticated air.”69 In his paper of 1785 he had a similar objective, only this time the air was phlogisticated air, the other half of common air. Blagden
We conclude our account of Cavendish’s late chemical researches on air
Had there been no “chemical revolution,”
A change of this magnitude in chemistry required a number of developments, one of which was pneumatic chemistry
Lavoisier was slow to recognize the importance of Cavendish’s early chemical work. In his Essays Physical and Chemical, published in 1774, he showed a full appreciation of the work of Hales
At the time of his new experiments on air, Cavendish was familiar with Lavoisier’s efforts to eliminate phlogiston from chemistry and to introduce oxygen in its place
It might seem that Cavendish was slow to see the superiority of Lavoisier’s chemistry, but this would a misreading of the state of chemistry in 1784. It was not until the following year that the first French chemist, Berthollet
If Kirwan is to be believed, by the time of the new chemical nomenclature, Cavendish had already given up the old chemistry. In a postscript to a letter of one of the authors of the Nomenclature chimique, Guyton de Morveau
At the end of his paper in 1784, where he said that the principle of phlogiston and Lavoisier’s
Cavendish had strong feelings about the language of chemistry, as we know from his correspondence with Blagden, who was away from London on the French and English triangulation project in 1787. The French party crossed the Channel carrying anti-phlogistic chemical publications including a copy for Cavendish of the new Méthode de nomenclature chimique
In 1788 an English translation of the new nomenclature came out. Adoption of it was relatively slow, given British reluctance to use French words or their Anglicized versions and, in some cases, to part with phlogiston. In his treatise on chemistry in 1790, William Nicholson
Late in life, Cavendish used Lavoisier’s names on occasion.95 Around 1800, he returned to an experiment he had carried out much earlier, probably in or around 1783, on the distillation of charcoal producing fixed and inflammable airs. Upon carrying out new computations, he concluded that the experiment showed that either the “charcoal contains hydrogen as well as carbon & water or else that the charcoal after distillation containd some oxygen.” In this passage he used terms he had not used at the time he made the experiment, “carbon,” “hydrogen,” and “oxygen.” He also spoke of “phl. Air” not “azote” in the same place. His chemical vocabulary was a mix in this case.
Earlier in this book where we take up Cavendish’s chemical work in the 1760s, we discuss phlogiston. Having considered Cavendish’s explanation of his experiments in the 1780s, we return to the discussion here. The Stahlian principle provided a theory that covered a wide range of chemical behaviors, not only combustion but also acidity, alkalinity, chemical reactivity, and chemical composition. As with most any general theory, it met with difficulties. One difficulty was accounting for the gain in weight of combustibles when burned and of metals when calcined, since according to the theory they have lost something, phlogiston
Like other phlogistic chemists, Cavendish observed the gain of weight of the product, the caput mortum, of burned and calcined substances without seeing it as an important problem. In his first surviving chemical research, he explained the weight of the caput mortum of arsenic by its retention of some of the aqua fortis used in making it, even performing an experiment to support his conclusion.97 Not drawn to speculations about phlogiston like those mentioned by Lavoisier, Cavendish regarded phlogiston as a respectable chemical substance, which happened to be wrong.
With hindsight, what Lavoisier and Wilson said about phlogiston is reasonable, for what came after was ever so much better. Yet something can be said in defense of phlogiston, which Cavendish’s later biographer Berry recognized: “Cavendish was able to use the phlogistic hypothesis successfully for his own purposes, and that for him was sufficient. The progress of science has shown that its pathways are littered with discarded theories, which, nevertheless, rendered good service in bygone times.”99 Phlogiston provided chemistry with a theory, and without a theory Cavendish would not have done any work in chemistry. With the theory available to him he was able to make major contributions to the science. If there had been a better theory when he started out, he would have used it, and the results he obtained would have reflected it. We can say that his experiments on air were a late success of phlogiston chemistry, while acknowledging that the significance of his late experiments became evident with Lavoisier’s anti-phlogistic chemistry.
Lavoisier and his colleagues brought together British pneumatic chemistry with Continental analytical chemistry in a “new synthesis of chemical theory.” Cavendish helped prepare the groundwork for the new theory of chemistry
The Jacksonian professor at Cambridge, Isaac Milner
In a paper in early 1784, as we have seen, Cavendish identified the product of the explosion of two airs with water. He, Watt
Basically a priority dispute, the water controversy arose from the following events, which are partly familiar to us. In the spring of 1781, Priestley
The water controversy begins here. After reading Cavendish’s paper, Deluc wrote to Watt that Cavendish “expounds and proves your system, word for word, and makes no mention whatever of you.” He wrote a second letter a few days later cautioning that “it is yet possible Mr. Cavendish does not think he is pillaging you, however probable it is that he does so.” Deluc told Watt that Cavendish must have read the letter he wrote to Priestley, which circulated among fellows of the Royal Society, before drawing up his own paper. Cavendish was a plagiarist.108 Watt accepted Deluc’s suspicions about Cavendish. By not revealing all of what Blagden had told him about Cavendish’s and Watt’s work, Lavoisier also laid himself open to the charge of plagiarism. Distressed by Lavoisier’s representation of Cavendish’s work, Blagden took a variety of measures, public and private, to set matters right. Lavoisier readily acknowledged that Blagden had told him about Cavendish’s experiments before he carried out his own.109 He stood corrected; he did not covet a discovery so much as all of chemistry, and the experiments on water had told him how to get it.
The passion behind the water controversy was decidedly Watt’s. He told Deluc that he did not depend on the favor of “Mr. C: or his friends; and could despise the united power of the illustrious house of Cavendish, as Mr. Fox calls them.”110 Cavendish was a rich man with a mean spirit, Watt wrote to another correspondent.111 When Watt saw Cavendish’s paper he recognized that it was different than his, and next year, 1785, Watt and Cavendish met in Birmingham
Much of the controversy revolved around datings of experiments, publications, and meetings. The datings were genuinely tangled, as this brief review will indicate. Soon after Warltire’s experiments on the ponderability of heat were published in 1781, Cavendish began his experiments on the production of water from the explosion of airs. Before 26 March 1783 his experiments were communicated to Priestley; before 26 April 1783 Priestley’s repetition of Cavendish’s experiments was communicated to Watt, who promptly sent Priestley an explanation of them; and before 24 June 1783 Cavendish’s experiments were communicated to Lavoisier by Blagden. Cavendish’s own account of his experiments was only read to the Royal Society on 15 January 1784. A further complication came from the Royal Society’s practice of permitting authors to make changes in their papers between the time they were read and their publication. Cavendish’s paper contained three insertions, made at different times, in one of which he said that his experiments on the explosion of inflammable air with ordinary or dephlogisticated air were made in the summer of 1781. The year 1781 was an important date because the Royal Society did not learn of the experiments until 1784. Watt and Lavoisier did their researches later than Cavendish, but since they made their views known earlier, they appeared, Wilson
The controversy was started by Deluc. Wilson thought that Deluc was an honorable man “whose motives are beyond suspicion,” but who was guilty of the “grave charge” of accusing Cavendish of stealing Watt’s theory without informing himself thoroughly. The charge was baseless, as Deluc could readily have determined.115 Deluc and Cavendish had a long association. When for financial reasons, Deluc left his native Switzerland to settle in England, Cavendish brought him as his guest to a meeting of the Royal Society a month before his election.116 He and Deluc served together in the Society, performed experiments together, corresponded, and disagreed civilly. Drawing on a common fund of knowledge about human behavior, we can imagine that the reason for Deluc’s intervention was more complex than carelessness alone, but lacking evidence as to its nature, we accept Wilson’s appraisal.
Like Deluc, Blagden had a role in the water controversy not as a claimant to the discovery but as an intermediary between persons who were. As Deluc’s complicity was built into his relationship with Watt, Blagden’s was with Cavendish. Blagden’s association with Cavendish was his scientific passport, while at the same time his zealous regard for the reputation of Cavendish was a vulnerability, which was compounded by his duty as secretary of the Royal Society of editing papers for publication in the Philosophical Transactions. Latter-day champions of Watt made out Blagden to be a villain, but he was guilty not of the unfairness and venality with which he was charged but only of neglecting his own best interest. Nor was Cavendish guilty of exploiting Blagden’s dependent position to get him to commit fraud on his behalf.
With the remote exception of Deluc, there was no malice on the part of anyone. When the steps leading to the dispute are examined one by one, as Wilson and others have done, this conclusion seems inescapable: a major reason for the “controversy,” as distinguished from a common scientific disagreement, was the casual way scientific information was communicated in the eighteenth century. The discovery of the nature of water was timely, and the stakes were high, so that otherwise tolerable exchanges by letters, conversations, and visits, with their indifferent datings, could, with proper incitement, seem darkly suspicious. As it turned out, precisely because there was also disagreement of the usual kind, different interpretations of the same experiments, there was recognition to go around. Cavendish was the first consciously to produce water by detonating airs; Lavoisier was the first to analyze water into its component airs; and Watt and Lavoisier were first to state unequivocally the compound nature of water.
A second water controversy arose long after the participants in the first were dead, prompted by the secretary of the French Academy D.F.J. Arago
In his biography of Cavendish in 1851, after meticulously examining all the documents relevant to the water controversy Wilson reached the conviction he began with, that Cavendish was the discoverer of the compound nature of water and that his character was blameless. He returned to the subject in 1859, after two new documents had come to light, strengthening his argument. One of them was a publication on meteorology by Deluc, who related a conversation with Priestley in 1782, which Wilson said removed “all trace of charge against the fair-dealing of Cavendish.” The other document was by Laplace
As a result of the water controversy, Cavendish and the German journal Chemische Annalen
Crell wanted to publish Blagden’s short history of Cavendish’s discovery, and although Blagden had not intended it for the public, he had no objection, since it was “strictly true.” He only hoped that Crell’s German translation would rather “soften than strengthen the expressions,” since however poorly Lavoisier had behaved in this affair, he was “upon the whole a very respectable character & eminent as a philosopher.” In keeping with his invitation to Crell, Blagden enclosed scientific news having to do with “Mr. Cavendish, whose name I shall so often have occasion to mention in this correspondence.” This time it was about Cavendish’s new work on the freezing of mercury rather than the history of his old work.120
The German chemist knew that Cavendish was an aristocrat but little about English titles. “The Honourable Henry Cavendish (not My Lord),” Blagden corrected him, “desires to become one of your subscribers.” To this end, Cavendish had given directions to the post office to ensure that he received the journal promptly.121 Six months later, Blagden wrote to Crell that the postmaster at Amsterdam had told him that some of Crell’s packets were held up because of their large size and were probably irrecoverable, a problem which could have been anticipated, since Banks had gone through it with Crell the year before.122 Crell had sent the material not by post but by stagecoach or wagon, Blagden said, conveyances which were not “connected with but in opposition to the Post.” When Cavendish succeeded in receiving a few issues of the Chemische Annalen and its supplement, the Beiträge, by post, Blagden instructed Crell to send Cavendish the rest by post as well. However, when after three months the remaining issues had not yet arrived in London, Blagden complained to the post office and then to Crell: “Mr.Cavendish pays many times the original value of the work to have it in this manner quick by the post; but the various delays have entirely frustrated that object.”123 The post office proved not to be a better way. Two years later the business of delivery was at last settled and the correspondence on that subject ended: “Mr.Cavendish finds it more convenient to get the Ch Annalen,” Blagden wrote to Crell, “in the common way, tho’ a little later, then to be perplexed with the post office; he […] will not give you any further trouble on the subject.”124
There were other complications, for example, the manner of payment for the subscription, of how much and to whom; Blagden told Crell to appoint some person to collect Cavendish’s money. Kirwan and Banks wanted to subscribe, and the journal could not be sent to everyone “through the same channel under one cover.” In addition to the journal, there were other publications by Crell that Cavendish wanted. He had ordered Crell’s Auswahl aus den neuen Entdeckungen, but his German bookseller had disappointed him. Crell offered to copy out the material Cavendish wanted, but Cavendish wanted the entire volumes.125
To convey scientific publications from Britain to Germany was not simpler. Blagden sent a copy of Cavendish’s latest paper to Crell in a packet, which he gave to William Herschel
Cavendish took evident interest in Crell’s Chemische Annalen
In his work in the basic fields of electricity, heat, and chemistry, Cavendish developed general theories for two of them, electricity
Chemists mostly agreed that the object of chemistry was to separate compounds into their parts, to study the parts, and to reunite them to form the original compounds or to produce new compounds. That describes what chemists did in the laboratory, but it fails to mention the help they had from outside, which included theory. In his Dictionary of Chemistry, Macquer
It was common for textbooks on chemistry to present the “theory” of chemistry followed by the “practice” of chemistry
We know a good deal, however, about Cavendish’s thoughts on “specific theories”130 of chemistry, which showed how chemical phenomena of certain kinds were related to one another. Examples of specific theories are the “theory of neutral salts,”
We briefly recall the original theory. According to the chemist and historian of chemistry Thomas Thomson, the first chemist to establish a general “theory” of chemistry “by which all the known facts were connected together and deduced from one general principle,” was Becher
In Berlin Stahl created a school of phlogistic chemists, who included Caspar Neumann
As mentioned earlier, unless they read foreign works, English chemists learned about phlogiston through Neumann’s lectures and a successful textbook on chemistry by Macquer, Elements of the Theory and Practice of Chemistry. Macquer’s
Cavendish’s chemical researches made extensive use of phlogiston; more than that, they were directed to phlogiston and its activity, the core of the current theory of chemistry descended from Becher
There is the beginning of a specific theory in Cavendish’s paper “On the Solution of Metals in Acids,”
We turn to another line of chemical theory, introduced earlier in this book. Newton
The most important early developer of Newtonian chemistry was Stephen Hales
In 1727, the same year as Hales’s book, there appeared an English translation of Herman Boerhaave’s New Method of Chemistry
Cavendish was a chemist such as Macquer described, one of the very few who were skilled in both mathematics and chemistry
In importance, calorimetry
The word “affinity” has come up several times. In place of “attraction,” some chemists preferred “affinity,” which implied nothing about laws of force. They recognized that substances have specific affinities for one another, forming unions, which are discovered in the laboratory. Historically, affinity was associated with the alchemists’ animistic sympathy or love, which was still a way of thinking in chemistry in the eighteenth century. Stahl
Affinities drew the attention of chemists around the same time as phlogiston, in the middle of the century.154 After the writings by Stahl and Boerhaave
When Cavendish took up chemistry, affinities were arranged in empirical tables
It took some time for Geoffroy’s table to receive notice in Britain. Peter Shaw
Tables of affinity were overly simple, occasionally exceptionable, and because of the complexity of salts they were incomplete, among other shortcomings. Most chemical reactions involved more than two substances, and the effect of the circumstances of a chemical reaction, particularly the temperature, qualified the usefulness of the tables, though later ones corrected for some of the deficiencies. Imperfect as they were, tables nevertheless were highly useful. They showed the building blocks of chemical compounds and the known compounds corresponding to a given substance, bringing order to the bewildering variety of chemical operations, analogous to the later periodic table, and like the periodic table they were predictive.163 They had the additional virtue of not being linked to a particular theory of chemistry, instead providing common ground for chemists holding different views. Chemists sometimes associated affinities with Newtonian natural philosophy, but this was not fundamental, as is shone by other chemists who used affinities to make chemistry an autonomous science independent of natural philosophy. Chemists were more likely to speak of the “doctrine” of affinity than of the “theory,” though the ultimate goal of affinity tables was theory, and the tables received criticism for lacking a theoretical base. A historian of chemistry writes of affinities as a “theory domain,” which by the 1770s, around the time Cavendish first published on chemistry, was the “frontier of theoretical chemistry.”164 Affinity tables did not represent nature in the way that theories of natural philosophy did, identifying the causes behind the phenomena, but they ordered and foretold the phenomena that chemists regularly dealt with in their daily work, accomplishing what theories do, qualifying perhaps as a theory of a different kind or a proto-theory.
When chemists spoke of wanting their science to be like natural philosophy, they usually had in mind useful mathematical laws of chemistry deduced from experimental facts.174 Black
When after completing his paper on the theory of electricity, Cavendish found that Aepinus
One key to Cavendish’s accuracy was his understanding of instruments
14.14 John Smeaton’s Air-Pump. The left-hand figure shows A barrel, B cistern, C handle of cock, D pipe communicating from cock to receiver, E pipe between cock and valve, GI siphon gauge. The right-hand figure shows the new gauge, a glass holding about a half pound of mercury, held up by the brass piece DE and open at A; the graduated tube BC is closed at C. While the receiver is being exhausted, the gauge is suspended in it. When the pumping is done, the gauge is lowered so that its open end is immersed in a cistern of mercury. The air is then let in, driving mercury up into the gauge until the air remaining in it is of the same density as the external air. The rarefaction of the air in the receiver can then be read off from the number of divisions occupied by the air at the top. Cavendish noted that the air trapped in the gauge contains water vapor; compressed by the mercury, the vapor at a certain point is turned into liquid water, eliminating the partial vapor pressure and thus allowing readings of unprecedented rarefactions. In other gauges of the time, this phenomenon did not occur. The gauge is described by its inventor, John Smeaton (1752b, 421); illustration of the air-pump opposite, 424. Cavendish’s analysis of the pair-gauge is given by Edward Nairne, PT 67 (1777): 622.
When someone objected to his explanation of the difference between the gauges, Cavendish said that the objection would be credible except for a “circumstance” he neglected to mention: “while any air is left in the receiver the pressure therein will be greater than if it contained only the vapor of water.”183 The circumstance was the principle of partial pressures
In addition to Cavendish’s and the Royal Society’s early precision balances, there was a third one, owned by Lavoisier
Measuring and weighing, the recording of objects in numbers, presuppose standards
Cavendish introduced the word “equivalent”
Cavendish applied the concept of equivalents throughout natural philosophy. In his theory of heat, he proposed an experiment to measure the mechanical “equivalent” of heat
In several experimental fields, Cavendish introduced the law of reciprocal proportions
It is clearer to us than it was to Cavendish’s contemporaries that his direction in chemistry would prevail. British resistance to Lavoisier’s
As indicators of the trend, we note several examples of measuring and weighing in the late eighteenth century and the beginning of the nineteenth century, a time when about a third of chemical publications were quantitative.207 The examples have been mentioned earlier in different contexts. Carl Friedrich Wenzel
Concern with accuracy was at the same time concern with error. Cavendish would seem to be preoccupied with error, but he was practicing good science as it was increasingly done. Francis Wollaston
Cavendish’s direction in science may have had sources outside of science as well. The caution with which he moved through his life has a parallel in his analysis of the circumstances of experiments, a point we take up in the last chapter. There may have been an additional source arising from his place in society.
Playfair (1822, 1:xxxv).
Pierre Joseph Macquer (1771, 1:iii–iv).
John Pringle (1774), Supplement at the end of the volume.
Tiberius Cavallo (1781, 797, 801).
Aaron J. Ihde (1964, 40–50).
Joseph Priestley (1767, xxii).
Joseph Priestley (1772b, 210).
Cavallo (1781, 453–457).
Ihde (1964, 47).
Wilson said this technique might be called an “Acoustic Eudiometer” (1851, 41).
Cavallo (1781, 665).
Cavendish, Mss II, 5:130.
Henry Cavendish (1783a, 127).
Most of the sheets are small folded pairs, with an occasional sheet folded four ways. Cavendish (1784a, Cavendish Mss II, 5).
Cavendish (1783a, 129, 137). The eudiometer Cavendish described in 1783 was not what later became known as the “Cavendish Eudiometer,” which the Cavendish Society adopted as its emblem in the early nineteenth century. The emblem is a pear-shaped, later version of the instrument, which Cavendish would not have recognized, an electrically detonated eudiometer invented by Alessandra Volta. Cavendish used an electrically detonated globe in his experiments involving the production of water, discussed later in this chapter, but he never referred to it as a eudiometer. Wilson (1851, 42–43). Kathleen R. Farrar (1963).
A.J. Berry (1960, 58–59). Jan Golinski (1992, 125).
The standard for an air containing less oxygen than common air is found by making an artificial mixture of common air and nitrogen, and adjusting the mixture until one measure of common air and a variable measure of nitrogen experience the same contraction, that is, have the same test. Cavendish gives a formula for calculating the standard in this case. If x is the quantity of nitrogen added to 1 part of common air, the standard of the air in question is 1/(1 + x). Cavendish (1783a, 130–131, 141–142). Wilson (1851, 228).
Cavallo (1781, 458–467, 477). Felice Fontana (1779). Rembert Watermann (1968, 302–303).
Cavendish (1783a, 140). Wilson (1851, 226–227).
William H. Pepys (1807, 249).
Separated off from his “Experiments on Air” is a 14-page paper containing eudiometer tests made in London, at his home at Great Marlborough Street, and in Kensington, “Miscellaneous Data on Eudiometer Experiments, 1780–81” (not Cavendish’s label), Cavendish Mss II, 8. He continued his tests after moving to Hampstead in 1782, where he recorded “Register of Test Air,” Cavendish Mss, Misc. There is another untitled manuscript comparing his, Fontana’s, and Ingen-Housz’s methods. Peter Brimblecombe (1977). Bent Søren Jørgensen (1967).
Charles Blagden to Benjamin Thompson, 27 May 1787, draft, Blagden Letters, Royal Society 7:55.
Golinski (1992, 93).
Pepys (1807, 259). W. Allen and W.H. Pepys (1808, 249).
Henry Cavendish to Charles Blagden, 18 Dec. ; in Jungnickel and McCormmach (1999, 713).
Cavendish (1783a, 144).
Thomas Baldwin (1785, 2).
In a letter from Joseph Black to James Lind, in William Ramsay (1918, 77–78).
Charles Blagden to Le comte de Cat[–]lan., 2 Apr. 1784, draft, Blagden Letterbook, Yale.
W.A. Smeaton (1974). Charles C. Gillispie (1983, 15–31).
Charles Hutton (1795–1796, 1:35–39).
For his sketch of Cavendish in 1845, Henry Brougham borrowed two manuscripts which are now lost: “Theory of Kites” and “On Flying.” Their existence and loan to Brougham are noted in Cavendish’s manuscripts at Chatsworth.
Alexander Aubert to William Herschel, 13 Sep. 1784, Royal Astronomical Society, Herschel Mss M1/13. Charles Blagden to Joseph Banks, 16 Sep. 1784, Banks Correspondence, Royal Botanic Gardens, Kew, l.173. Charles Blagden to Joseph Banks, 17 and 21 Oct. 1784, BM(NH), DTC 4:75–76, 77–78. Henry Cavendish, “Air Taken by Dr. Jeffries: Tried Dec. 3, 1784.” The standard was taken of this air for several samples and compared with “Air Taken at Hampstead at the Time of the Trial.” Two years earlier, samples of air from a balloon were compared with air “taken out at Mr. Cavendish’s S. window at Hampstead at the same time. Nov. 28, 1782.” Henry Cavendish, “Path of Balloon,” for Blanchard and Sheldon’s ascent on 16 Oct. 1784. Cavendish Mss VIII, 9, 24. Henry Cavendish, “Result of Observations of Balloons,” Blagden Collection, Royal Society, Misc. Notes, No. 86. Cavendish’s papers contain a testimonial signed by Benjamin Franklin, among others, of a Montgolfier experiment on 21 July 1783, and also an extract, in Blagden’s hand, about Montgolfier from the Journal Encyclopédique. Archibald and Nan L. Clow (1952, 156).
He did not publish this finding, the credit for it going to Gay-Lussac for his research twenty years later. Henry Cavendish, “Eudiometer Results of Air Taken by Dr. Jeffries,” and “Test of Air from Blanchard Balloon,” Cavendish Mss II, 9. Thorpe (1921, 22). Jeffries’s air samples were numbered, but because Cavendish’s manuscripts do not contain the explanation of the numbers, the test was believed lost. However, recently it was located in Jeffries’ account of his flight, from which the earliest atmospheric profile, the “Cavendish-Jeffries profile,” has been reconstructed. It shows that at the various sampling elevations, between one and three kilometers, the amount of oxygen in the air over London was virtually constant. Brimblecombe (1977, 365).
Notations in both Blagden’s and Cavendish’s hand, beginning “Smoke of Straw,” Cavendish Mss Misc.
Charles Blagden to Claude Louis Berthollet, 5 Dec. 1783, draft, Blagden Letterbook, Yale.
Charles Blagden to Claude Louis Berthollet, 19 Dec. 1783, draft, ibid.
Joseph Banks to Charles Blagden, 22 Sep. and 12 Oct. 1783, Blagden Letters, Royal Society, B.29–30.
Charles Blagden to Joseph Banks, 24 Oct. 1784, ibid., 83–84.
Charles Blagden to Joseph Banks, 26 Oct. 1784, Blagden Letters, Royal Society, B.32.
Hutton (1795–1796, 1:139).
Cavallo (1781, 401–420). It is indicative of the activity in pneumatic chemistry that in his 1784 paper Cavendish referred to eight current investigators: Bergman, Kirwan, Lavoisier, Priestley, Scheele, Senebrier, Warltire, and Watt.
Priestley (1772b, 162–163, 210–212, 225, 228, 232).
Henry Cavendish (1784b, 161). Thorpe (1921, 23).
Joseph Priestley (1781, 395–398).
Cavendish (1784b, 165). His laboratory accounts: “Experiments on Air,” Cavendish Mss II, 5:115.
This discussion draws on Russell McCormmach (1969, 305).
Cavendish (1784b, 167).
Wilson (1851, 435).
Thorpe (1921, 35). The chemist Berry, Cavendish’s biographer, writes that there is ambiguity in Cavendish’s statement, “I know no way by which phlogiston can be transferred from one body to another, without leaving it uncertain whether water is not at the same time transferred.” Brock writes, “The difficulty is centred around the question as to what Cavendish understood by phlogiston. … He seems to have regarded hydrogen as a hydrate of phlogiston.” Brock (1992, 110). Berry (1960, 86–87).
Wilson (1851, 326–328).
Cavendish (1784b, 173–174).
Henry Cavendish (1785). Thorpe (1921, 47).
Cavendish (1784b, 169–171). Thorpe (1921, 33). Wilson (1851, 442). Berry says that “nowhere in his chemical work does the genius of Cavendish appear more clearly” than in his explanation of the appearance of nitric acid upon exploding the gases with an excess of oxygen. (1960, 73).
Cavendish (1785, 191, 194).
Berthollet told Blagden that his letter created great interest in Paris in Cavendish’s “beautiful experiments.” Claude Louis Berthollet to Charles Blagden, 17 June 1785, Blagden Letters, Royal Society, B.126.
Martin van Marum to Henry Cavendish, 6 Jan. 1786; Henry Cavendish to Martin van Marum, undated, draft; in Jungnickel and McCormmach (1999, 622–625). Cavendish published this letter in his paper, “On the Conversion of a Mixture of Dephlogisticated and Phlogisticated Air into Nitrous Acid by the Electric Spark,” (1788b, 232).
The witnesses were Banks, Blagden, Heberden, Watson, John Hunter, George Fordyce, J.L. Macie, and Johann Caspar Dollfuss; William Higgins and Richard Brock came on the day after an “accident” happened, and Cavendish did not list them in his paper. T.S. Wheeler and J.R. Partington (1960, 33, 66).
Jean Senebier to Henry Cavendish, 1 Nov. 1785; in Jungnickel and McCormmach (1999, 611–618)
Henry Cavendish, “Paper Communicated to Dr Priestley,” Cavendish Mss, Misc. Vernon Harcourt, Presidential Address, British Association Report (1839), 3–68, on 64. Scheele too studied this gas, perhaps as early as 1771, but he did not publish his results until 1777. E.L. Scott (1975). Priestley came upon it independently too. Ihde (1964, 38).
There are two versions of the way Cavendish’s experiment came to the notice of Rayleigh. We have given Ramsay’s. Rayleigh’s was that he was first informed of Cavendish’s experiment by James Dewar. Morris W. Travers (1956, 100–107).
Berry (1960, 178–179).
William Ramsay (1896, 143). Bruno Kisch (1965, 8).
Cavendish (1784a, 161).
Charles Blagden to Thomas Blagden, 8 Dec. 1785, Blagden Letterbook, Yale.
Joseph Priestley to Henry Cavendish, 30 Dec. 1784. Priestley’s letter was in reply to Cavendish’s, written in late 1784, which summarized the main points of what would become the published paper of the following year. Henry Cavendish to Joseph Priestley, 20 Dec. 1784, draft; in Jungnickel and McCormmach (1999, 598–599, 602–603).
Henry Cavendish, “Projectiles,” “On the Motion of Sounds,” Cavendish Mss VI(b), 14, 35. Cavendish (1771, 43).
“Introduction,” A.L. Donovan (1988, 5–12, on 5–6); Siegfried (1988, 34–50, on 34–35).
Thomas Thomson (1830–1831, 2:115).
Changes that underlay the Chemical Revolution are summarized in Brock (1992, 84–85).
Greenaway (1776/1970, xxiii, xxix).
Cavendish (1784b, 179–181). Thorpe (1921, 37).
Thomson (1830–1831, 2:136–137).
Ibid. 2:101, 130.
Charles Blagden to Claude Louis Berthollet, 21 and 24 May and 28 June 1785, drafts, Blagden Letterbook, Yale.
Charles Blagden to Joseph Priestley, 11 June 1785, draft, ibid.
Charles Blagden to William Cullen, 5 July 1785, draft, ibid.
Charles Blagden to Claude Louis Berthollet, 17 Nov. 1787, draft, Blagden Letters, Royal Society 7:85.
Scottish chemists were receptive. Black early lectured on the new chemistry, though he did not commit himself until 1790. Thomas Charles Hope, who succeeded him at Edinburgh, lectured on the new theory after 1787.
Blagden to Berthollet, 17 Nov. 1787.
3 Apr. 1788, Certificates, Royal Society 5.
Cavendish (1784b, 181).
Thomson (1830–1831, 2:348).
From Dover, Blagden wrote to Cavendish in London that he had the book and would hold it if Cavendish planned to join him or forward it to Banks’s address where Cavendish could pick it up. Because of foul weather, Cavendish did not go to Dover, with the result that he and Blagden discussed the nomenclature by letter. Charles Blagden to Henry Cavendish, 16 Sep. 1787; Henry Cavendish to Charles Blagden, n.d. [after 16 Sep. 1787], draft, in Jungnickel and McCormmach (1999, 634–635, 638–640). Charles Blagden to Claude Louis Berthollet, 17 Nov.1787, draft, Blagden Letters, Royal Society 7: 85.
Cavendish to Blagden, [Sept. 1787].
Charles Blagden to Henry Cavendish, 23 Sep. 1787, in Jungnickel and McCormmach (1999, 641–644).
“Dr Black has just made a new chl nomenclature: I think he might have been better employed”; J.-H. Hassenfratz’s chemical shorthand was thought to serve no “useful purpose” in England; and James Watt risked his reputation with his chemical algebra. Charles Blagden to M.-A. Pictet, 12 Feb. 1790, draft, and to James Watt, 6 Dec. 1788, draft, Blagden Letters, Royal Society 7:402 and 7:185.
Nicholson (1790, viii; 1795, 1:vii). Maurice Crosland (1962, 193–206).
Charles Blagden to Georgiana, duchess of Devonshire, 4 Jan. 1794, Devon. Coll.
In computations around 1800, Cavendish used “hydrogen” and “oxygen“: Henry Cavendish, “Experiments on Air,” Mss II, 5: 390. In a letter to Blagden about a paper by Humboldt on the eudiometer, Cavendish used Lavoisier’s name for phlogisticated air (our nitrogen) “azote.” This was in 1798, some ten years after his “sermon” on Lavoisier’s new chemical nomenclature. Henry Cavendish to Charles Blagden, 18 Dec. , Blagden Papers, Royal Society.
Brock (1992, 83–84, 111–112).
Cavendish, “Arsenic,” Cavendish Mss II, 1(b), 14.
Wilson (1851, 36–38).
Berry (1960, 183).
Henry Guerlac (1959, 109, 112).
Following the publication of Lavoisier’s Treatise, writings of chemists revealed “widespread confusion and uncertainty” over the nature of elementary substances and the naming of compounds, as if they “knew they couldn’t go back to the old way of thinking, but were quite unsure of which way was forward.” Robert Siegfried and Betty Jo Dobbs (1968, 275–276).
L.J.M. Coleby (1954, 256).
George Fordyce (1792, 374).
Humphry Davy (1808, 33).
Wilson (1851, 282).
Ibid., 285, 290–293.
Ibid., 337, 344–345.
Jean André Deluc to James Watt, 1 Mar. 1784, Watt (1846, 48–49). Wilson (1851, 407–408).
Wilson (1851, 362).
James Watt to Jean André Deluc, 6 Mar. 1784, Watt (1846, 48–49)
James Watt to Mr. Frey of Bristol, 15 May 1784, ibid., 61.
24 Nov. 1785, Certificates, Royal Society 5.
Watt, quoted in Samuel Smiles (1874, 169).
Wilson (1851, 60–61).
13 May 1773, JB, Royal Society 28:132.
As Harcourt summarized Arago’s claim, in his Presidential Address, British Association Report (1839), 15.
Berry (1960, 87–88).
Among Cavendish’s manuscripts is a translation into English, not in Cavendish’s hand, of Crell’s translation into German of extracts from Cavendish’s paper of 1784, with Crell’s retraction of his earlier error. “Translation from Mr. L. Crell’s Chemical Annals, 1785. part 4, 324.” Charles Blagden to Lorenz Crell, 28 Apr. 1785, draft, Blagden Letterbook, Yale. Blagden’s letter, in English, clarifying the discovery to Crell was translated into German by Crell and translated back into English by Wilson (1851, 362–363). Wilson’s translation is reproduced in Berry (1960, 81–82).
Charles Blagden to Lorenz Crell, 2 Dec. 1785, draft, Blagden Letters, Royal Society 7:738.
Charles Blagden to Lorenz Crell, 20 Jan. 1786, draft, ibid. 7:742.
Lorenz Crell to Joseph Banks, , 17 Dec. 1785, 1 May 1786, 4 Mar. 1790, BL Add Mss 8096:69–70, 239–240, 284–285, and 8097:296–297.
Charles Blagden to Lorenz Crell, 4 July, 12 Aug., and 13 Oct. 1786, drafts; Charles Blagden to Charles Jackson at the post office, 10 Oct. 1786, draft, Blagden Letters, Royal Society 7:26, 44–45. By 4 July Cavendish had received the first and second issues of the Annalen and the fourth issue of volume 1 of the Beiträge. On 6 August, he was still waiting for the third through the sixth issues of the Annalen and the first through the third issues of volume 1 of the Beiträge.
Charles Blagden to Lorenz Crell, 4 Apr. 1788, draft, Blagden Letters, Royal Society 7:137.
Blagden to Crell, 4 July and 12 Aug. 1786.
Blagden to Crell 4 July 1786.
Charles Blagden to Lorenz Crell, , draft, Blagden Letterbook, Yale.
Macquer (1771, 1:xi–xii).
Macquer (1758, 1:15–18).
Term used by Mi Gyung Kim (2003, 5).
Macquer (1771, 1:xi–xii).
Thomson (1830–1831, 2:250–263).
Casper Neumann (1759, 53, 165).
Macquer (1758, 1:9–10).
Henry Cavendish (1921e, 2:305–307).
Isaac Newton (1952, 375–376).
Ibid., 376–77, 380–81.
John Keill (1708).
John Freind (1712). Translated from Praelectiones Chymicae (London, 1709).
Kim’s term, which applies here (2003, 4).
Stephen Hales (1727). Thomson (1830–1831, 2:303).
Herman Boerhaave (1727, 1:170–174). This book was based on student lecture notes, 1724. In 1732 Boerhaave published a treatise, Elements of Chemistry, which was translated by Peter Shaw in 1741. J.R. Partington says that in this book Boerhaave maintains that acid dissolves substances by motion, and that although he quotes Newton and uses mechanical analogies, the motion has a cause that is not mechanical. “Chemistry through the Eighteenth Century,” in Natural Philosophy, supplement to Philosophical Magazine, 1948, 47–66, on 48. The popularity of Elements of Chemistry warranted another English edition, 1753.
Newton, Principia 1:1.
Buffon explained his ideas about gravitation in his Histoire naturelle in 1765. Hélène Metzger (1930, 57–60, 63). A.M. Duncan (1962, 228).
Metzger (1930, 61).
Macquer (1771, 1:324).
A.M. Duncan (1970, 31).
Henry Cavendish, (1921c, 347).
Henry Cavendish, “Hypothesis All Bodies in Changing from a Solid State …,” Cavendish Mss, Misc.
Henry Cavendish, “Heat,” in Russell McCormmach (2004, 182–183).
Robert Fox (1971, 22).
Kim (2003, 15, 387, 392–393).
A.M. Duncan (1962, 184–185; 1970, 33–34). Macquer (1771, 1:22–23).
Kim (2003, 222). Duncan (1970, 190).
Macquer (1758, 1:12).
Ibid. 1:14. Kim (2003, 207).
Torbern Bergman (1785b, 9).
Metzger (1930, 50). Duncan (1970, 177).
Bergman (1785b, 65–70).
Georgette Nicola Lewis Taylor (2006, 61–63).
Christlieb Ehregott Gellert (1751).
Gellert’s book was translated by John Seiferth in 1766 as Metallurgic Chymistry, though it was not published until ten years later. Fathi Habashi (1999, 34–35). Duncan (1962, I:187–189; II:220–221). Antoine Baumé (1763, 7).
Ursula Klein and Wolfgang Lefèvre (2007, 152).
Duncan (1962, I:181; 1970, 34). Taylor writes that though affinity was not tied to a certain theory, affinity tables were “guided and determined by theoretical assumptions,” and that different chemists had different theories of affinity (2006, 8, 16, 21, 28). Kim (2003, 222).
Fourcroy quoted in Arnold Thackray (1970, 202).
Duncan (1970, 29).
Ibid., 5, 41–42. Kim (2003, 342–343).
Henry Guerlac (1961, 206–207).
Kim (2003, 14, 16, 220).
Macquer (1771, 1: Advertisement)
William Lewis (1763, iii–iv).
Cavallo (1781, 157).
Duncan (1970, 26).
Quoted in Brock (1992, 271).
John G. McEvoy (1968, 117).
Frank Greenaway (1776/1970, xii).
Henry Cavendish (1771, 33).
6 Nov. 1766, JB, Royal Society 25:927.
James Keir, quoted in Joseph Priestley (1788, 327).
Humphry Davy (1812, 37).
This clarification of the air pump in 1776 was described by Nairne in a paper and by Charles Hutton in his entry “Air” in Mathematical and Philosophical Dictionary (1795–1796, 1:56–57).
The person Cavendish addressed is not named. Cavendish Mss IV, 4.
S.A. Dyment (1937, 473).
Ernest Child (1940, 79). Maurice Daumas (1972, 134, 222–223). Precision balances first appeared in assaying offices, in the 1770s.
From a list of Henry Cavendish’s servants at his death in 1810, we know that his instrument maker’s name was William Harrison, who was sixty-one at that time. It could be another Harrison. Cavendish’s balance is attributed to Thomas Harrison in Mary Holbrook (1992, 169). It is attributed to John Harrison by Maurice Dumas, who says that only a clock-maker would have had the skill to make it (1972, 134, 222).
Charles Blagden (1790, 325).
William Nicholson, in his translation of notes by French chemists to the French edition of Richard Kirwan (1789, viii).
Wilson (1851, 363).
Daumas (1972, 225–226).
Lavoisier could be careless at times. When he and Laplace burned oxygen and hydrogen to obtain water, they did not keep track of the exact quantities of the gases, assuming that the weights of the gases and of the water formed from them were equal. According to Blagden, who witnessed it, Lavoisier and Laplace’s first experiment on the production of water was “good for nothing as to determining the proportions of air & water,” and their only dependable result was the test of the purity of water; they intended to repeat the experiment with the “necessary precision,” but the account of this first experiment was read before the Academy of Sciences anyway. Charles Blagden to Joseph Banks, 25 June 1783, BM(NH), DTC 3:56–58. Henry Guerlac (1975, 78).
Charles Blagden to Claude Louis Berthollet, 8 Dec. 1789, draft, Blagden Letterbook, Royal Society 7:377.
Pierre Simon Laplace to Charles Blagden, 7 May 1785, Blagden Letters, Royal Society, L.181.
Marie Boas Hall (1972). J.R. Partington (1961–62, 3:44–45).
Black (1898, 17–18).
Partington (1961–62, 3:320).
Cavendish (1766, 93).
McCormmach (2004, 134–135).
Cavendish Mss II, 2(b). Unnumbered pages at the end.
Cavendish Mss III(a), 9:82.
In addition to neutral salts, Cavendish prepared solutions of fixed alkali and acids. Maxwell found that when the amounts of the salts and acids are expressed in pennyweights, they are very nearly equal to their equivalent weights in modern chemistry, where the equivalent weight of hydrogen is taken as 1. The remarkable agreement is not just in ratios but in absolute numbers, which comes from Cavendish’s practice of using as a standard the equivalent weight of marble, the modern value of which is 100. By taking 100 pennyweights of marble as the standard, the equivalent weights of the other salts and acids come out as Cavendish stated them. Henry Cavendish (1879h, 329–330; 1879k, 360–361). Maxwell’s commentary, ibid., lxii–lxiii.
Henry Cavendish (1879b, 114–115).
Henry Cavendish (1921c, 340).
Wilson pointed out Cavendish’s use of the “law of reciprocal proportion.” A certain quantity of sulfuric acid saturates a given quantity of a particular alkali, and a different certain quantity of nitric acid saturates the same quantity of alkali. This quantity of nitric acid dissolves 33 parts of marble. It follows from the rule that the above quantity of sulfuric acid also dissolves 33 parts of marble. Cavendish estimated the strength of acids by the quantity of marble they dissolved, but because in the case of sulfuric acid, the quantity of marble it dissolved was not an accurate method, he estimated its strength by comparing it with nitric acid, which was accurate. This is why he took the roundabout way, making use of reciprocity. Wilson (1851, 465).
Jan Golinski (1992, 130–152).
A.L. Donovan (1975, 201, 215, 220–221; 1993, 49). Brock (1992, 117).
H. Gilman McCann (1978, 143–146).
Ihde (1964, 96).
Richard Kirwan (1781, 8–9; 1783, 34, 36, 38).
Guerlac (1961, 197, 199, 203–205, 211).
Francis Wollaston to William Herschel, 22 Mar. 1789, Royal Astronomical Society, Herschel Mss W 1/13, W.193. William Herschel to Samuel Vince, 15 Jan. 1784, ibid., W 1/1, 92–95, on 93.
James Hutton (1794, 6).
Howard T. Fry (1970, xiii).
Witold Kula (1986, 18). Kisch (1965, 8).
Table of Contents
Part I: Lord Charles Cavendish
Part II: The Honorable Henry Cavendish
14 Air and Water
17 Last Years
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