Isaac Newton and the Aerial Nitre

Isaac Newton and the Aerial NitreAuthor(s): A. Rupert HallSource: Notes and Records of the Royal Society of London, Vol. 52, No. 1 (Jan., 1998), pp. 51-61Published by: The Royal SocietyStable URL: http://www.jstor.org/stable/532076 .

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Notes Rec. R. Soc. Lond. 52 (1), 51-61 (1998)

ISAAC NEWTON AND THE AERIAL NITRE

by

A. RUPERT HALL, F.B.A.

14 Ball Lane, Tackley, Oxon OX5 3AG, UK

On 6 January 1713 Isaac Newton wrote to Roger Cotes, his assistant in preparing the second edition of his Philosophiae naturalis principia mathematica, then in the press at Cambridge: 'I shall send you in a few days a Scholium of about a quarter of a sheet to be added to the end of the book ...'1 However, it was only on 2 March that Cotes actually received the copy for the 'General Scholium' from Newton, whose drafting processes now proceeded slowly; moreover, there had been Mint business in the interval. In a short accompanying letter Newton also informed Cotes of his decision not to say 'much more about the attraction of the small particles of bodies', a topic to which Newton would return in the late Queries added to Opticks.2

Thus we know exactly when Newton completed his draft of the 'General Scholium' on God and the Universe, to which only minor alterations were made in the course of printing. There is, nevertheless, a certain mystery about the final paragraph of the Scholium. This reads (my translation):

It would be possible to add not a little about a certain very subtle spirit pervading dense bodies and lying hid in them, by whose force and actions the particles of bodies attract each other at the very smallest distances, and which when they are brought into contact causes them to cohere; and by this spirit electrified bodies act at greater distances, both attracting and repelling little objects in their vicinity; and light is emitted, reflected, refracted and inflected; and bodies grow hot; it stimulates sensation, and causes the limbs of animals to be moved at will, for the vibrations of this spirit travel through the solid fibres of the nerves from the external organs of sensation to the brain, and from the brain to the muscles. But these matters cannot be handled in a few words; nor do we have that sufficiency of experimental information from which the laws of action of this spirit should be established and proved.3

We are now quite well informed about the context of the main topic of the 'General Scholium', indeed Newton himself had already begun to reveal it, notably in Quaestio 23 of Optice (1706). The careful reader of Bentley's Confutation of Atheism (1693) would have learned more.4 Without exegesis, however, the sense of the word spiritus in the passage just quoted is far from plain. Was it to be read in a physical or a religious sense? Newton's 'spirit' must be possessed of extraordinary efficacity, producing as it does almost all the phenomena of nature that Newton had examined. He had not been afraid to assert in 1706 that God, directly active on all things material and immaterial, is 'a powerful ever-living Agent, who being in all Places, is more able by his Will to move the Bodies within his boundless Sensorium, and thereby to form and reform the parts of the Universe, than our Soul which is in us the Image of God, is able by its Will to move the Parts of our own Bodies' . The 'spirit' might be one of God's vehicles in

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© 1998 The Royal Society



A. Rupert Hall

so directing the universe. Did Newton perhaps mean-as he hinted to Richard Bentley in letters unprinted till 1756,-that God's own spirit was thus omnipresent, conferring upon substance and especially living substance properties that mere brute matter could not possess?6 Such a notion would have been fully in conformity with the metaphysics of Henry More, an early mentor of Newton, and was one that continued to appeal to him in his maturity.7 However, we now know, thanks to Professor I. Bernard Cohen, that to an interleaved copy of the second edition of the Principia Newton added the adjectives electrici & elastici before spiritus in the final sentence. Omitted in the third edition as prepared by Newton and Henry Pemberton, for reasons unknown, they re-emerged in Andrew Motte's English translation of the Principia (1729) as 'electrick and elastick spirit'. Setting a metaphysical interpretation of the passage to one side, this version endows the versatile spirit with at least some physical properties and indicates that Newton had a physical agent in mind whose nature and whose experimental basis he would further elucidate four years later in the final edition of Opticks prepared by him (Queries 17 to 24, interpolated into this edition).

All this is familiar; it is perhaps less well-known that Newton had from the first, in 1687, introduced another (physical) spirit into his mathematical picture of the universe, in a passage making it plain that he gives the word the technical chemical meaning of his time. In the revised structure of the third edition it appears only 15 pages before the spirit of the 'General Scholium'. This spirit is more specific than that electric and elastic spirit and less universal, though hardly less mysterious. For elucidation, it is well to turn to the original text of 1687 where it occurs in the penultimate proposition on comets (Prop. 41).

Towards the end of this long proposition Newton discusses the nature of comets' tails, developing his view that they consist of very fine, subtle matter streaming from the coma or atmosphere of the comet which, in turn, is matter vaporized from the nucleus under the intense heat of the sun (about 2000 times as hot as glowing iron, according to Newton's estimate). The tail, Newton notes, is wider at its remote extremity than at its origin, and follows the line of heat-radiation from the sun, as smoke ascends from a fire. Though the matter of the tail is extremely rare, its particles possess gravity, and are not contained by the totally void space into which they slowly diffuse and scatter.

It seems reasonable that this vapour, dispersed by its perpetual rarefaction, should be diffused and spread through all the heavens, then is gradually drawn to the planets by its gravity and mingles with their atmospheres. For just as the seas are absolutely necessary for the formation of this earth, in order that vapour may be copiously exhaled from them under the heat of the sun, which vapour either descends as rain after its condensation into clouds and so waters and nourishes the whole earth for the growth of plants, or else when condensed on the cold summits of mountains may run down as springs and rivers (as some philosophers suppose, not without reason); so likewise comets seem to be necessary for the conservation of the seas and fluids of planets. For their exhalations and vapours, when condensed, may continually make good and restore whatever fluids are used up and converted into dry earth by the growth and decay of plants. All plants grow wholly from fluids, then for the most part vanish in dry earth by decaying; a mud always falls down from fluid putrefactions. Hence the dry mass of earth increases daily, and fluids (unless recruited from elsewhere) must continually decrease and at length fail altogether. Further, I suspect that that spirit which is the least part of our

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Isaac Newton and the aerial nitre

air, but the most subtle and best, and which is needed by every living thing, comes particularly from comets (my italics).8

This whole long passage was hardly modified in subsequent editions. Curiously- but it reveals the degree of his conviction-Newton returned to the same idea, now extended even further, in new material added to the end of Proposition 42 in the second edition of 1713:

The vapours arising from the sun, the fixed stars and the tails of comets may, because of their gravity, encounter the atmospheres of planets and be there condensed and converted into water and moist spirits; afterwards they may little by little change, by gentle heat, into salts and sulphurs and tinctures, mud and clay, sand and stones and corals, and other earthy substances. However, as the body of the sun grows less the mean motions of the planets around the sun will gradually slow down, and as the earth grows larger the mean motion of the moon around the earth will gradually increase. And our country-man Halley, by comparing some observations of eclipses by the Babylonians with those of Albatenius and of our own age, was the first man to detect that the mean motion of the moon has gradually accelerated in comparison with the daily motion of the earth.9

The last two sentences, moving from the geological transmutations of the globe's crust to their astronomical consequences, were struck out from the third edition of the Principia.

The earlier part of this passage on the derivation of pregnant vapours from the emptiness of space seems to be closely related to Newton's repeated expressions during his 'middle period' of a hypothesis of the circulation of fluids in the cosmos, fluids which serve as the origin of all inorganic and organic matter on earth. Some legacy of the philosopher J.B. van Helmont may perhaps be seen in them-the Leyden 1667 edition of Ortus medicinae, the chief repository of van Helmont's writings, was in his library-as well as of even more esoteric writers.'° Newton's recollection of experiments by van Helmont and Boyle seeming to demonstrate the conversion of water into dry earth by plants is obvious. The admissibility of the total transformation of matter by natural processes, not necessarily to be reduplicated by human hands, was commonplace in the 17th Century. Indeed, Newton himself specifically asserted it, without comment, in the third of his 'Hypotheses' (in later editions, retitled 'Rules of Reasoning') opening Book III of the first Principia (1687):

Every body can be transformed into a body of any other kind whatever, and be endowed with all successive intermediate degress of quality."

The 'Hypothesis', irrelevant enough in this place, was deleted from later editions of the book.

This kind of transformation, known to Newton as 'vegetation', employing this word in both an ordinary and an esoteric sense, was highly important in Newton's middle period thought, as B.J.T. Dobbs has emphasized.12 Manuscript drafts and a paper formally read and recorded by the Royal Society set out Newton's speculative notion of an 'aetheriall spirit', not (he wrote) the 'maine body of flegmatic aether' but rather 'something very thinly & subtily diffused through it, perhaps of an unctuous or Gummy, tenacious and Springy nature'.

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A. Rupert Hall

The long discussion of aetherial spirit occurs in Newton's 'Hypothesis explaining the Properties of Light, discoursed of in my several Papers', submitted to the Royal Society on 7 December 1675 and read at meetings on 9 and 16 December. The paper can hardly be dismissed as a mere fantasy orjeu d'esprit-though it seems to have been in part inspired by Newton's desire to show that he could frame hypotheses with the best-and therefore must be read as expressing the genuine results of Newton's deep reflections about nature's mysteries, reflections to which, indeed, he returned in variant forms again and again.

The passage in question follows Newton's allusion to the irregular motions provoked by electrical attraction and repulsion motions, which (he thought) must spring 'from some kind of subtil matter lying condens'd in the glass and rarified by rubbing ...' Some other such like aetherial spirit, he speculated, might be the cause of gravity and bear 'much the same relation to aether, which the vital aerial spirit, requisite for the conservation of flame and vital motions, does to air'.

For if such an aethereall Spirit may be condensed in fermenting or burning bodies, or otherwise inspissated in ye pores of ye earth to a tender matter wch may be as it were ye succus nutritious of ye earth or primary substance out of wch things generable grow or otherwise coagulated, in the pores of the earth and water, into some kind of humid active matter for the continual uses of nature, adhering to the sides of those pores after the manner that vapours condense on the sides of a Vessell subtilely set; the vast body of the Earth, wch may be every where to the very centre in perpetuall working, may continually condense so much of this Spirit as to cause it from above to descend with great celerity for a supply ... For nature is a perpetuall circulatory worker, generating fluids out of solids, and solids out of fluids, fixed things out of volatile, & volatile out of fixed, subtle out of gross, & gross out of subtle.13

We need not here pursue further this aspect of Newton's mystery of nature, already fully explored by Mrs Dobbs. That his 'final' aetherial speculations in public (in Queries 17-24, published in 1717) are indebted to these early musings seems obvious enough. And again one notices another application of that gloriously indefinite word 'spirit'. I rather return to that cosmic spirit of the Principia to which at least some firm historical context can be fitted.

Newton's vital spirit of the atmosphere belongs to an old tradition whose latest (and now best known) expression had been provided recently by John Mayow (1641-1679).14 Mayow's star shines less brightly now than in the days when he was taken to be an English precursor of Lavoisier in the discovery of oxygen, but his significance in providing strong experimental backing for an old tradition of ideas is unassailable. Mayow demonstrated that a volume of air enclosed in a vessel over water was reduced by burning material in it and by the respiration of a small animal. In

appropriate circumstances the smaller volume of air remaining above the water was found to be inert (Tractatus quinque medico-physici, 1674). No-one yet thought of some product of combustion/respiration dissolving in the water, but it was clear that either some constituent of the air had been removed, leaving only the inactive bulk, or that its elasticity had been reduced and so its power of supporting life and combustion. These two possibilities could be made equivalent. This removable constituent of the air Mayow termed variously 'nitro-aerial particles' or 'nitro-aerial

54




spirit'; the particles were 'absolutely indispensable for the production of fire, and ... in the burning of flame are drawn from the air and removed, so that the latter when deprived of these particles ceases to be fit for supporting fire'.'5 Mayow had already argued in a parallel manner about respiration in his Tractatus duo (1668).

We may analyse Mayow's hypothesis into a series of interlocking propositions: (i) the atmosphere, like all matter, consists of an aggregate of particles, all more or less elastic; (ii) only one type of these various particles reacts with combustible matter or living tissue; (iii) this type forms only a small fraction of the whole; (iv) the reaction is exothermic whether in a flame or living tissue; (v) without it neither combustion nor life is possible. The last point had been indirectly demonstrated by air-pump experiments; we need not follow the physiological ramifications of Mayow's hypothesis further. With these propositions Mayow and others combined a further group, logically independent of the former: (a) these active particles which are free and mobile in air are fixed in nitre (saltpetre); (b) the same particles, liberated from nitre by heat, support combustion in the absence of air; (c) released from nitre in the soil without heat they strengthen the life of plants and perhaps (d) animals. The evidential backing for the second group of propositions was more anecdotal than that for the former set: gunpowder could be fired in vacuo; nitre and nitrous material like animal dung fertilized plants; Cornelius Drebbel claimed to have refreshed the air in his wooden submarine boat from nitre, and so on. The two sets taken together constituted the evidence for the existence of a single entity, nitro-aerial particles, occurring both in nitre and in the atmosphere, otherwise named nitro-aerial spirit or simply 'aerial nitre'. The fundamentally novel element in this hypothesis, which Boyle's air-pump might be held to have stimulated, was in the concept of only a part of the atmosphere's being involved actively in both chemical and physiological processes, rather than the air's being merely a passive medium or vehicle whose effects (as in the blowing of a fire with bellows) might be explained as merely mechanical (in a simple sense).

This hypothesis seems to have commended itself to early Fellows of the Royal Society. Sir George Ent (1641), Ralph Bathurst (1654), Kenelm Digby (1661), Robert Hooke (1665), Richard Lower (1669) and Thomas Willis (1670) all contributed to the development of the 'nitro-aerial' hypothesis before, or about the same time as, Mayow. Among other Englishmen advocating in print all or most of the propositions listed above were Malachi Thruston (1670) and Nathaniel Hodges (1671).16 Robert Boyle, on the other hand, confessed that he had not 'been hitherto convinced of all that is wont to be delivered about the plenty and quality of the nitre in the air: for I have not found, that those, that build so much upon this volatile nitre, have made out by any competent experiment, that there is such a volatile nitre abounding in the air.17

Mayow, therefore, with his large claims, was quite rejected by Boyle; yet it is only the fullness, detail and experimental backing provided by Mayow that distinguished his treatises from the earlier tradition. Hooke, for example, devoted three pages of Micrographia (1665) to his 'Hypothesis' that:

the dissolution of sulphureous bodies is made by a substance inherent, and mixt with the Air, that is like, if not the very same, with that which is fixt in Salt-peter, which by multitudes of Experiments that may be made with Saltpetre, will, I think, most evidently be demonstrated.

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A. Rupert Hall

Hooke treated combustion as a simple exothermic chemical reaction between the sulphur in the combustible and the saline menstruum [solvent] of the air, which is but a fraction of the whole atmospheric mass, as is

the nature of those Saline menstruums, or spirits, that have much flegme mixt with the spirits, and therefore a small parcel of it is quickly glutted, and will dissolve no more.

hence the utility of forced draught in a furnace. Hooke thought his hypothesis, raised 'from an Infinite of Observations and Experiments', of which he detailed none, would yield 'an intelligible, nay probable, if not the true reason of all the Phaenomena of Fire ...'18 Anticipating Mayow and others, Hooke promised to extend his hypothesis to respiration in a later discourse, but in his briefer compass he did not speculate as Mayow did, after the manner of Descartes, about the mechanism of the interaction between the various particles that produced combustion.

In his notes upon Micrographia Newton recorded Hooke's hypothesis in some detail, without comment:

from ye manner of charing cole may be concluded yt the air is the Menstruum or universal disolvent of all sulphurious bodys, it selfe being (as it were) a flegmatick body but abounding with parts such as are fixed in salt peeter wch parts are true dissolving bodys & being but few in the aire a fresh supply must bee continually made by bellows &c (hence ye use of respiration) or otherwise made least ye flame goe out for ye aire like other menstruums is quickly glutted & will dissolve noe more without a fresh suply & then it consumes as quick as melted niter it selfe.19

My guess is that in 1665 these notions were new to Newton. Within the next five

years he began to explore chemical and alchemical writers, and to experiment himself; thus he entered the world from which the hypotheses of Ent, Digby, Hooke and others had emerged in a more positive guise.

Many years ago Henry Guerlac, from Digby's allusion to 'the Cosmopolite', traced the Paracelsan origins of the idea of a 'secret food of life' existing in the air, particularly quoting from a book by a supposed Polish alchemist, Michael Sendivogius (1556-1636), of whom nothing is positively known. Novum lumen chymicum (A New Light ofAlchymie is the title of the English text, 1650) was first printed in 1614. Newton possessed three copies of this mysterious book: one in Latin (Geneva 1639), showing signs of much use; one in French (Paris 1691; could this have been a gift from Fatio de Duillier?); and one in English (as above).20 By contrast, Newton owned no copy of Micrographia, no work by Mayow, Lower or Thruston. I shall argue in a moment that Newton preferred this original source to the later versions of the 'nitrous' hypothesis. He left extensive annotations on it.

Guerlac's account was fair and accurate, but failed to make the crucial point that Sendivogius when employing names like 'water', 'dew', 'quicksilver' and 'nitre' does not refer to the ordinary substances to which in his time as in ours these names are applied. He refers to 'our Nitre', dew and so forth, that is, philosophical or esoteric substances. He does not say that ordinary nitre is found in the air. Sendivogius writes more than once about 'the secret food of life', 'the vital spirit of every creature, which lives everywhere, penetrates everything, and furnishes the seed to the other elements

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as the man to the woman', and which provides life to all things.21 But this is only a romantic view of the obvious. Sendivogius's two allusions to 'nitre' are hardly chemical: Take ten parts of our air, he writes, one part of quick-gold or quick-silver, put all in your vessel, and cook it with the air, firstly so that it becomes water and then not water; if you do not know how to do this you will surely fail, for the air is the true matter of the philosophers.

For you must take what is, though it is not to be seen until the Operator pleases; it is the water of our dew, from which the philosophers' saltpetre is drawn; upon this all things grow and are nourished. Its womb is the centre of the sun and of the moon both celestial and terrestrial, and to speak plainly to you it is our magnet, that I have formerly called steel.22

The second mention of nitre occurs after an even more esoteric passage that I can neither understand nor translate, about the rays of the sun and moon which combine to 'produce flowers and all things':

This is why, when it rains, the rain receives from the air a certain living force and combines it with the nitrous salt of the earth (which is just the same as calcined tartar) which by its dryness attracts the air to itself and resolves it into water; and this nitrous salt of the earth has the same power to attract the air, because it has itself been air and is combined with the fatness of the earth, and the more the sun's rays are strong, copious and abundant, so much more of the nitrous salt is made and by consequence more grain grows on the earth, as daily experience teaches us.23

More than matter-of-fact chemistry is involved: this nitre is not just the 'villanous saltpeter ... digged out of the bowels of the harmless earth' to make gunpowder but a transcendental power. Sendivogius's are 'clearly mystical (or poetical) truths, to be judged not according to their immediate meaning but from their contribution to producing a meaningful life-world'.24 Newton almost certainly shared this opinion.

We see, then, that a transformation rather than a mere borrowing created from Sendivogius's words that matter-of-fact, indeed mechanical, hypothesis of Hooke, Lower and Mayow, with its context in post-Cartesian particulate physics, of which the alchemist had no inkling. That Newton rejected the transformation of Sendivogius's original notions may be seen from a passage in his paper for the Royal Society of December 1675, purposely omitted from the previous quotation. Newton wrote, in his draft, that

the gravitating attraction of the earth [may] be caused by the continual condensation of some other such aetheriall spirit ... bearing much the same relation to aether, wch the vital areall Spirit requisite for the conservation of flame & vital motions (I mean not ye imaginary volatile saltpeter) does to Air.25

The words in parentheses do not appear in the Royal Society's copy (printed by Birch) because Newton, on 25 January 1676, asked Henry Oldenburg, the Secretary, to delete 'that Parenthesis least it should give offence to somebody'. Whatever Newton's exact

meaning when he expressed the same generic idea in the Principia some 11 years later, allowing it to stand in all editions, it is clear that in 1675 his own thoughts were closer to those of Sendivogius than to the mechanistic hypothesis of Hooke and Mayow. His

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A. Rupert Hall

use of the word 'spirit' and avoidance of 'particle' is itself indicative of his reluctance to embrace (here, at least) a purely mechanical or corpuscular chemistry.

Returning to those puzzling, final words of the later Principia texts, it is amusing to note that in one draft of the paper just discussed the words 'electric effluvia' appear where 'elastic effluvia' stand in the revision received by the Royal Society and subsequently printed by Birch, indicating not only the equivalence of these two adjectives in Newton's mind, but the consistency of his thought over many years, even on minor points.26

CONCLUSION

In this paper I have dealt with some aspects of Newton's notions of air and aether; at one time he began to compose an essay entitled De Aere & Aethere. Probably no one now imagines that the celebrated declaration in the last lines of the Principia, Hypotheses nonfingo, was ever meant to have universal application, out of its context. For it is clear that though Newton did not assert hypotheses as truths, he framed them throughout his life, and indeed made them known to the world. Newton's major printed works frequently assume or invoke hypotheses; not to dwell again on the axioms categorized as such at the opening of Book III of the 1687 Principia, it is evident that the relevance of Book II of that work to the physical world rests on hypotheses about the nature and properties of both elastic and inelastic fluids, among which that of Proposition 23, introducing a fluid whose particles repel their immediate neighbours with a force inversely proportional to the distance between them, stands out as remarkable. As Newton remarks, 'whether elastic fluids do really consist of particles so repelling each other is a physical question', which he does not attempt to answer. He has examined a possible hypothesis mathematically. In Book I, Propositions 94-96, a quite different if equally odd hypothesis of attraction is proposed for consideration: the force is everywhere equal. In the cases of particulate motion here treated by Newton the 'sine-law of refraction' and the 'equal angles law of reflection' are derived from the hypothesis, enabling Newton to suggest that such 'attractions bear a great resemblance to the reflections and refractions of light'.27 Furthermore, in the Scholium following these Propositions the hypothetical model of particulate attraction is extended to account for diffraction, whose phenomena at that time (1686) were imperfectly understood by Newton.

Turning once more to Book III, in the revised editions of the Principia Newton approved for the theory of the moon a truly Ptolemaic hypothesis (devised by Edmond Halley) supposing the centre of the moon's orbit to revolve 'in an epicycle whose centre is uniformly revolved around the earth'.28 No physical reasons for this are given. The utility of all these various hypotheses, of very different character, was obviously that they enabled Newton to develop mathematical models of well-known physical phenomena such as Boyle's Law and Snel's Law, even at the cost of proposing purely hypothetical (and indeed unlikely) ad hoc laws of attraction.

The same is equally true of Opticks. Not to multiply examples, the 'Fits of easy

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Reflexion' and 'Fits of easy Transmission' (introduced before Proposition XIII, Book II, Part III of Opticks) constitute an hypothesis essential to Newton's explanatory account of the phenomena of optical interference. Other, equally ad hoc, hypotheses- the 'sides' of rays in Query 25, to account for double refraction, for example-are proposed as required. All these, and others, we may regard as examples of Newton's use of specific hypotheses of limited application, the question of consistency or compatibility between them not arising. Newton was as prepared to face the possibility of their being multiple laws of attraction in the universe as of their being multiple kinds of particles (or atoms).

This use of specific hypotheses contrasts with his introduction on several occasions throughout his life of a general hypothesis whose function in nature is fundamental and universal. This is, of course, his aether hypothesis; first revealed to an audience in his paper to the Royal Society of December 1675, again in modified form imparted to Robert Boyle in the letter of 28 February 1678/79; it makes a glancing appearance in the various editions of the Principia (most plainly, if tersely, in the concluding paragraph of the General Scholium) then reaches its fullest expression in print in Opticks, Queries 17-24 (1717). This is not the place for a minute examination of the development and exploitation of this general hypothesis by Newton, nor for seeking to relate its various manifestations to the evolution of his experimental researches and ideas about particular phenomena. It is of course obvious that the expositions of this general hypothesis on various occasions do not square one with another, and that they are adapted to fill diverse explanatory functions. Each exposition has its own ad hoc elements. A

philosopher might argue that the very flexibility of the Newtonian aetherial hypothesis testifies against its usefulness, equally with its untestability. However, the repeated enunciation of the aetherial hypothesis in its various forms can be seen only as evidence of the constant necessity for such a universal, non-mechanical philosophy as a feature of Newton's idea of nature, though we need not necessarily take it to be the dominant or paradigmatic feature; Newton's mind also wrestled more intensely, more positively and ultimately more creatively with the problems of analyzing nature in terms of mathematics, forces and motions. It is a curious paradox that the man who accomplished such giant strides in this latter form of inquiry should also have been drawn to a very different and (may one say?) more romantic model of explanation. Perhaps we may juxtapose Newton's aetherial hypothesis with his deep distrust of the philosophical and theological implications of a purely mechanistic physics so strongly evident not only in his letters to Richard Bentley and those of Samuel Clarke to Leibniz, but in the concluding passages of both his great scientific works.

NOTES

1 H.W. Turbull, J.F. Scott, A.R. Hall and Laura Tilling (eds) The Correspondence of Isaac Newton, vol. V, p. 361 (Cambridge University Press, 1977).

2 Ibid. p. 384. For a draft 'Conclusio' to the Principia dealing with forces between particles, see A. Rupert Hall and Marie Boas Hall, Unpublished scientific papers ofIsaac Newton pp. 320-347 (Cambridge University Press, 1962, 1978); for a draft of the 'General Scholium'

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A. Rupert Hall

elucidating such forces see ibid. pp. 348-364. The former draft seems to relate to the first edition of the Principia, the latter to the second.

3 Alexandre Koyre and I. Bernard Cohen (eds), Isaac Newton's Principia, the third edition with variant readings, vol. II, pp. 764-765 (Cambridge University Press, 1972); cf. Florian Cajori (ed.) Sir Isaac Newton 's Mathematical Principles, p. 547 (Berkeley, 1946).

4 On p. 8 of A confutation of atheism from the origin andframe of the world Richard Bentley introduces the concept that weight is always proportional to mass: 'This is the ancient Doctrine of the Epicurean Physiology [i.e. Physics], then and since very probable indeed but very precariously asserted: But it is lately demonstrated and put beyond controversy by that very excellent and divine Theorist Mr. Isaac Newton, to whose most admirable sagacity and industry we shall frequently be obliged, in this and the following Discourse.' A marginal reference is to Principia, Book III, Prop. 6.

5 Optice, 1706, p. 346. I model my English version on the (lightly re-written) English in Opticks, 4th edn (1730) (cf. Dover edn, 1952, p. 403).

6 See Four letters from Sir Isaac Newton to Doctor Bentley (London 1756), reprinted in I. Bernard Cohen (ed.), Isaac Newton's papers & letters on natural philosophy, pp. 279-312 (Harvard University Press, 1958, 1978).

7 The locus classicus is in Newton's MS. De gravitatione et aequipondiofluidorum (see Hall and Hall, op. cit. (note 2), pp. 138-145). In later years Newton was still pleased enough with this notion to impart it to Locke, who treated it seriously (see Alexandre Koyre, Newtonian studies, p. 92, note 1 (Harvard University Press, 1965).

8 Principia (1687), p. 506, my translation. 9 Idem. (1713), p. 481, my translation. 10 John Harrison, The library of Isaac Newton (Cambridge University Press, 1978, no. 751). 11 Principia (1687), p. 402; cf. B.J.T. Dobbs, The Janus faces of genius, p. 23 (Cambridge

University Press, 1991). 12 Idem, ibid. ch. 2, 4 and Appendix A. Cf also Henry Guerlac, 'Theological voluntarism and

biological analogies in Newton's physical thought', J. Hist. Ideas 44, 219-229 (1983). 13 H.W. Turbull, The correspondence of Isaac Newton, vol. I, pp. 365-366 (Cambridge

University Press, 1959). The passage is drawn from more than one draft. The text actually read to the Royal Society on 5 December 1675 differs only slightly from this (which contains obvious duplications); see Thomas Birch, History of the Royal Society, vol. III, p. 251 (London, 1757).

14 Mayow was elected F.R.S. on 30 November 1678, on Hooke's proposal; he was never admitted. J.R. Partington, History of chemistry vol. II, pp. 577-614 (London, 1961) gives a full account of Mayow; see also Henry Guerlac, 'John Mayow and the aerial nitre', Actes 7 Cong. Int. d'Histoire des Sciences, pp. 332-349 (Jerusalem, 1953).

15 Partington, op. cit. (note 14), p. 593. 16 All of them are discussed by Partington; on Digby, Thruston and Hooke see also Guerlac,

'Aerial nitre'. 17 Boyle's General history of the air was posthumously published in 1692 but was surely

written long before; see Thomas Birch (ed.) Works of the Hon. Robert Boyle, 2nd edn vol. V, p. 627 (1772).

18 Robert Hooke, Micrographia, pp. 103-105 (1665). 19 Hall and Hall, op. cit. (note 2), p. 407. 20 See Harrison op. cit. (note 10), nos 445, 1192, 1485. On Sendivogius and his supposed

mentor Alexander Seton see Partington, op. cit. (note 14), pp. 426-429 and John Ferguson, Bibliotheca Chemica, vol. II, pp. 364-370 (London [1906] 1954). No original source material seems to exist other than Sendivogius's own writings, details of his life come from later authors.

21 Guerlac, op. cit. (note 14), p. 340. 22 Cosmopolite [Michael Sendivogius], Nouvelle Lumiere de la Physique naturelle ... Traduit

nouvellement de LATIN EN FRANCOIS par le Sieur de Bosnay, pp. 55-56 (Paris 1618); cf.

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Guerlac p. 341. 'Car tu dois prendre ce qui est, mais qui ne se voit pas iusques a ce qu'il plaise a l'Operateur, c'est l'eau de notre rosee, de laquelle est tire le salpetre des Philosophes, duquel toutes choses croissent & se nourissent. Sa matrice est le centre du Soleil & de la Lune tant celeste que terrestre, & a fin que ie le die le plus ouvertement, c'est nostre ayment, que par cydevant j'ay nomme Acier.'

23 Ibid. p. 58; cf. Guerlac p. 341. 'I'ay dit encores que le Soleil celeste a certaine correspondance avec le Soleil centrique, car le Soleil celeste & la lune ont une particuliere force de distiller sur la terre par leurs rayons, car la chaleur facilement se ioint a la chaleur, & comme le Soleil centrique a sa mere, & une cru perceptible, ainsi le Soleil celeste a sa mere, & une eau subtile & perceptible, en la superficie de la terre, les rayons se ioignent aux rayons & produisent les fleurs & toutes choses. C'est pourquoy quand il pleut, la pluye prend de l'air une certaine force de vie, & le conioint avec le sel nitre de la terre (lequel est tout de mesme avec le tartre calcine qui par la siccite attire 1' air a soy & le resout en eau) & ce sel nitre de la terre a une mesme force d'attirer 1'air, car il a este air luy mesme, & est conioint avec la graisse de la terre, & tant plus les rayons du Soleil sont forts, copieux, & en plus grande abondance, tant plus grande quantite de sel nitre se faict, & par consequent plus grande quantite de froment vient a croistre sur la terre, ce que nous enseigne l'experience de iour en iour.'

24 I borrow an expression applied to ancient Egyptian theology by Jens Hoyrup, 'A historian's history of ancient Egyptian Science', Filosofi og Videnskabsteori pa Roskilde Universitetscenter, 3 Raekke, no. 6, p. 7 (1996).

25 H.W. Turbull, Correspondence of Isaac Newton, vol. I, p. 365 (1959); cf. Thomas Birch, History of the Royal Society, vol. III, p. 251 (1757).

26 Turbull, ibid. vol. I, p. 364 and Birch, ibid. p. 250. 27 Principia, p. 231 (1687). 28 Principia, p. 423 (1713); p. 462 (1726).

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Isaac Newton and the Aerial Nitre