David F. Larder' Department of History and Philosophy of Science University of Aberdeen Aberdeen, Scotland
Historical Aspects of the Tetrahedron in Chemistry
Three dimensional chemistry is so familiar today that it is only with some difficulty that we can visualize a nonspatial or a-spatial approach to the science. It is a common misconception that spatial chemistry and the tetrahedral concept originated in the classic work of Le Be1 and van't Hoff. Without underemphasizing the importance of this work as a focal point on which later work has been based, and which has been discussed elsewhere (I),it is nontheless true that the tetrahedron has played five major chemical roles prior to this. By far the most important and useful, as it turns out, has been the tetrahedral arrangement of four atoms about a fifth at the center, but this is not to underestimate the importance of the tetrahedral shape of atoms and molecules, nor the arrangement of four atoms or subatomic particles. The tetravalence of carbon, although explicitly stated by Kekul6 in 1857 (8), and implied earlier by several workers (S),was not widely accepted until it was reiterated by Kekul6 (4) and Couper (6) in 1858. The enunciation of this concept, however, carried with it no speculation on spatial geometry (6), although in his Lehrbuch Kekul6 did consider atomic arrangements in space (7). In 1863,Butlerov commented that "thus far, consideration of the spatial arrangement of atoms for chemical purposes is unnecessary" (8). When Heintz suggested the more general extension of Butlerov's theory of chemical structure (9) to include the arrangement of atoms in space (lo),Markovnikov, Butlerov's student and champion, pointed out that from Butlerov's standpoint, the speculative nature of this suggestion was inconsistent with the thesis of chemical structure (11). It is, therefore, of particular interest that Butlerov in 1862 should be the first to postulate the concept of a tetrahedral carbon atom with, for example in methane, four hydrogen atoms bound to each face: Since the notion of this difference [between the affinities], as well as the amount of the affinity itself, arises only when it comes into play, then clearly we cannot speak of a n absolute difference of the uncombined affinity units, but only of the difference between the operation of a certain part of the affinity of the multivalent2 atom and the operation of another specific part of it. I n this way, if we may consider as a crude example a tetravalent carbon atom, represented as a tetrahedron, with all four affinity units different, each of the four faces having the ability to hind one atom of hydrogen, then we are not able to denote each face in a manner which will express its attraction and define its position; we nonetheless can assert that this attraction is different for each face, and we can describe this difference without knowing to which face this or that mode of operation belongs [(14)].S
Butlerov's choice of a tetrahedrally shaped carbon aton1is of interest since, from the time of Leukippos and Demokritus, the shapes of atoms have been thought to be important, and partly rmponsible for different qualities (17). Aristotle said that "the atoms [of Leucippos
and Democritus] differin figure, and all figures are composed of pyramids [tetrahedrons], rectilinear in the case of rectilinear figures, while the sphere has eight pyramidal parts" (de Caelo, 303a. 30f). Plato, in the Timaeus, associated the tetrahedron with Empedokles' element of fire, as also did Davidson (18)who, like Jerome Cardan in De Rerum Varietate (1557; lib. XIII, cap. W I I ) drew attention to the geometry of the tetrahedral figure, and the other Platonic solids. In 1690, when the atom and the molecule were not carefully distinguished, Bernoulli considered acid-alkali reactions in terms of attack by the tetrahedral atom of one on the spiked atom of the other (19),but later, the more definite idea of Thomson is closer to Butlerov's concept: Let us suppmc, for instance, that the particlwof sulphurie neid are tetrahedrons, and that the particles of p o t ~ . are i of such n form, thnt une of thrm can attach itself to each uf rhe sides of the acid particles [(ZO)].'
Thomson not only noted the dependence of adhesion, cohesion, and affinity on the figure of particles, but he also saw the advantage for inter-particle attraction of certain shapes: But if the particles of bodies have length, breadth and thickness, we cannot avoid conceiving them as composed of an indeterminate number of still more minute particles or atoms. Now the affinity of two integrant particles for each other must he the sum of the attractions of all the atoms in each of these particles for all the atoms in the other: But the sum of these attractions must depend upon the number of attracting atoms, and upon the distance of these atoms from each other respectively; and this distance must depend upon the figure of the particles. For it is obvious, that if two particles, one of which is a tetrahedron and the other a cube, and which contain the same number of atoms, be placed a t the same relative distance from a third particle, the
' The author is indebted to Dr. W. P. D. Wightman, F.R.S.E., for suggestions, advice and encouragement, and to Notre Dame Univemity of Nelson, British Columbia, Canads, for sabbatical leave currently being spent a t the University of Aberdeen. * The term valency was not introduced until 1864 (IZ),hut is preferable to the contemporary term atmnieity, which was resewed by Gaudin (13) for the number of atoms in a molecule, hut still used, for example by Frankland, in the sense of valency, after 1864. The German translation (15) would have heen more widely read by contemporary chemists, and differs little from the original. Butlerov had earlier considered the unequal carbon affinities: "The four affinity units of carhoninnlethsne. . .do not substitute with equal ease" ( 1 6 ) , and he suggested p r i m l y and secondary binding. He foresaw the large number of predicted isomers, such as four isomers for CFIaC1, but later thought that they might not exkt. ' H e notes a t the same time: "Affinity unites bodies of a different nature, not merely by one srtpeficies, as adhesion does, hut particle to particle like cohesion; and the most perfect cantsot is formed that the figwe of the particles will admit. Therefore, in this case also, tho intensity depends upon the figure of the particles" (20). Volume 44, Number 1 1 , November 1967
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sum of all the distances of all the atoms of the first. partiole from
all the atoms of the second particle, will be less than the sum of the distances of all the atoms of the second particle from the third [($I)].
Clearly Thomson was influenced by Boscovich's theory (see below), but it is evident also that he was prepared for the conceptually simpler atomic theory of Dalton, of which he gave the first published account (22). Dalton, in the ''New System," gave brief mention to the shapes of solid bodies: Crystallisation exhibits to us the effects of the natural arrangement of the ultimate particle8 of various compound bodies; hut we are scarcely yet sufficiently acquainted with chemical synthesis and analysis to understand the rationale of this process. The rhomboidal form may arise from the proper position of 4, 6, 8, or 9 globular particles, the cubic form from 8 particles, the triangular form from 3, 6, or 10 particles, the hexahedral prkm from 7 particles etc. [(83)1.S
Many of the early crystallographers took note of crystal form and drew attention to various geometrical shapes (26). Linnaeus, for example, considered his animal salt, "natrum," one of the saline principles responsible for crystallization, to have a tetrahedral shape, while Wallerius (27) thought that the figure of minerals was due to the metallic ingredients, which had shapes such as the tetrahedron for tin. But Bernhardi (28) pointed out that a regular tetrahedron could not be formed for copper pyrites, as suggested by Hauy, on the basis of the cubic or octahedral forms (irregular as well as regular), for copper, iron, and sulfur, without postulating empty space in the molecule. No chemical advances were made. Hooke, although not thinking in atomic terms, saw the importance of the tetrahedral figure, which could readily be formed from four small globules of lead or tin (29) : . . .t,hese regular figures.. .arise only from three or four several positions or postures of globular particles.. .and these I have ad oculum demonstrated with a company of bullets, and some few other very simple bodies; so that there was not any regular figure.. .that I could not with the composition of bullets or globules, and one or two other bodies, imitate, even almost by shaking them together.. .in solidity also, for it's obvious that a. fourth globule laid upon the third in this texture, composes 8. regular Tetrahedron, which is a very usual figure of the crystals of alum [(SO)]. 'Robert Boyle said nearly as much: "First, that by a bare Association of Metalline and Saline Corpuscles, a Concrete, as finely figur'd as other Vitriols, may be produced.. .. Secondly, because thst the Figures of these Salts are not constantly in all respects the same, but may in diverse manners be somewhat varied.. .. Thirdly, that insensible Corpusoles of different, but d l of them exquisite, shapes, and endowed with plain its well as smooth sides, will constitute Bodies variously, hut all vely finely figur'd.. ." (24). "For diverse of these Chrystalls have not only Triangles, I-Iexagons, and Rhomboides, and other figures exquisitely cut on their smooth and s~eoularsurfaces. and others. Bodies of Prismaticel shapes: But same of them are no lesse accurately figur'd than the finest Nitre or Vitriol I remember my self to have observ'd, snd some also teminzte in Bodies almost like Pyramids, consisting of diverse triangles, that meet in one Vertical point, and are no lesse admirably shap'd than the fairer sort of Cornish Diamonds" (26). "Any particular atom in a normal or defect tetrahedral structure will hrwe as next neighbours four other atoms which are located a t the vertices of a surrounding tetrahedron, of which E., "Crystal Chemisthe particular stom is the centre," PAETH~, try of Tetrahedrel Structures," Gordon and Breach Science Publishers Inc., New York, 1964, p. 3. Parthk correlates structure with valence electron concentration in inorganic tetrahedral structulw, structures cheracterised by tetrahedral bonding.
662 / Journd of Chemical Education
There are, in fact, three different alum structures, each of which belones to the cubic svstem, but differs in the internal arrangement of the structural units (51). Lomonosov attempted to account for crystal angles in terms of the packing of spherical particles. In his Meditatime de Solido et Fluido (1760; 5 20 and fig. 7), he indirectly draws attention to a regular tetrahedral arrangement of four particles. Boscovich applied to particular phenomena the general ideas of Newton regarding the constitution of nature, and had a substantial influence on many nine teenth century chemists. In his Theoria (52) of 1758 he considered that "lhe primary elements of matter are in my opinion perfectly indivisible and non extended points" (33) which are separated at certain limit points or distances of stable equilibrium in particles of thc first order ( 3 4 , the distances for repulsion, attraction, and equilibrium being described in his famous curve (55). He considered the specitic case of four atoms forming a tetrahedron, when . ..four point., not in the same plane can be so situated thst they
-
preserve their relative position vary tenaciously; and that too, when we make use of but a sinele distance rorres~andinet o
.
upon points, or pyramids of the same kind. . . From four particles of this kind, arranged to farm a. larger pyramid, we can obtain a.parbide of the second order. . . [MI.
Wollaston considered the arrangement of four particles about a fifthqo be in equilibrium "if the four particles are situat,ed at the angles of the four equilateral triangles composing a regular tetrahedron" (ST), but at the same time, shnrtly after Thomson had published Dalton's atomic views, he sounded a cautionary note that "it is perhaps too much to hope, that the geometrical arrangement of primary particles will ever be perfectly known. . ." (57). In his Bakerian lecture of 1812, he was more conf dent while reaching similar conclusions: Let a mass of matter be supposed to consist of spherical part,icles all of the same size, but of two different kinds in equal numbers, represented by black and white halls; and let it be required ihat in their perfect intermixture every black ball shall be equally distant from all surrounding white balls, and ahat all adjacent, balls of the snme denomination shall also be equidistant from each other, I stty lhen that these conditions will he fulfilled if the arrangement be ethical, and that the particles will be in equilibria.. [and] their configurstion [of fom black balls] represents a regular tetrahedron; and the same is the relat,ive situation of the four white balls [38].
.
This paper includes illustrations of particle packing to account for crystal structure. However, the development was considered independantly of the atomic theory, since his hypothesis required, instead of indivisible ultimate physical atoms, merely the mathematical points of Boscovich whose "extent is virtually spherical, for from the union of such particles the same solids will result as from the combination of spheres impenetrably hard" (58). That spatial ideas were being considered during the first half of the nineteenth century is evident from Baudrimont's definition of a molecule: "Several atoms collected (rhnis) together and arranged in a symmetrical manner in space, make up a corpuscular system which Ampere has termed a molecule" (59). Ampere had earlier considered the minimum number of n~ole-
cules in a particle, meaning at,oms in a molecule in the modern sense, to be four and tetrahedrally arranged, if the volume of the particle was to he greater than the sum of the volumes of the constituent molecules. He suggested that the space occupied . . .will be a polyhedron of which each molecule will oeciqy a summit, and it will he sufficient to name thiv polyhedrun [which is the representative form of the particle] in order to express the respective situat,ion of the molecules of which a particle is composed [401.
and later, in discussing the five primitive forms of the ~nineralogist,he considered first the simplest: Two molecules being snpposed to be united 013 a line, to give a clearer ides of their respective position; if we add thereto two other molecules mited in the same manner, a t first in one and the same plane, so that the two lines m n t ~ d ycut each other into two e q r d parts; and if we afterwards remove them, by keeping them alwsvs in a situation ~ a r a l l eto l that which the" had on t,his plan, we shall obtain a tetrahedron, which will be regrrlar in the rase only where the two lines were equally perpetdicdar to each other. . . [dl].
Pasteur, in reflecting on t,he optical pn~pertiesof the tartaric acids, briefly noted the possibiMy of geometrical arrangements: .&re the atoms grouped on the spirals of n helix (31. placed a t the s\munits of an irregular tetrahedron.. .? We am unable to answer these questions (46).
Thzy [dextro and laevo forms] ressemble each other as the right hand ressembles the left hand, or better, as l.wo irregdsr symmetrical tetrahedra; and these analogies and differences remain in all their derivatives [/+$I.
Ten years earlier Pasteur, unwittingly referring to solids, had commented that "all regular tetrahedra are superimposahle" (G),and so in 1860 he suggested irregular, nonsuperimposable arrangements. Spatial ideas were prevalent in organic chemistry during the sixties and early seventies of the nineteenth century. I n 1863 Wislicenus drew attent,ion to the spatial arrangement of atoms in an early paper on the lactic acids (45),while the followingyear Cariuv intimated the need for such an arrangement in the explanation of physical isomerism (46),and Bayma presented a Boscovichean stereochemistr~ Gaudin, a uuoil of - (47). .. . .4rnpBre, developed AmpBreJs ideas and sug&&ed, in 1865, the symmetrical arrangement of four hydrogen atoms about a carbon atom: Aloms group themselves around s calral alom l,o form symmetrieill systems.. .. This seems to me realised or realisable in methane which is composed, it is said, of s. carhon atom associated with four hydrogen stoms which ought to form a regular tetrahedron at the centre of which resides the carbon atom [48].
Gaudin's advanced ideas led van't Hoff (@) to think that in 1873 Gaudin (50)had been very close to solving the problem of the relative position of atoms in a molecule. Two years later Kekul6 considered the four valency units of carhon to pass from the spherical at,om and end in the faces of a tetrahedron: The incompleteness, in t,hc model a t least, may be avoided if the foitr valeney units of carbon, instead of lying in a plane, are allowed to run out from the atomic sphere in the direction of the hexahedral ares so that they end in the planes of R tetrahedron [XI.
Gillis (62)has found some annotations by KekulB on a
French translation of Butlerov's 1862paper (14) and 1 ~ ~ s indicated the probable path of the tetrahedron concept. Although ICekulB did not use this concept very 11-idely, he did comment that "with tetrabasic acids a tetrahedral arrangement appears likely, but not necessarily by a regular tetrahedron" (55). He used a three-dimensional model for structural illustration which Dewar, who worked with him, has described as consisting of . . .carbon, with ii.8 four atomicities, being represented by a small sphere, with four equal wire arms johing the centre of the sphere with the angles of an imsgina~yequilateral tetrahedron 1541.
Dalton, about 1810, had also used spatial models, cousisting of halls linked together with pins (56). Paternb, in 1869 at the age of 22 (56), postulated a three dimensional structure: Three isomeric Cz13rBds, supposing that they really exist, may easily be explained, without the need to assumes. difference in the four aftinifies of the carbon atom as Butlerov did 1141, if we postulate that the four valencies of the carbon atom are arranged toward the four angles of a regular tetrahedron [57].
He thus suggested a cis-trans type of isomerism for the two 1,2-dibromoethanes, which don't exist but were still being sought some sixty years later, without postulating free rotation about the carbon-carbon single bond, and came very close to the van't Hoff-Le Be1 theory. Although Xekul6 had given his benzene formula in 1865 (58) it was not totally acceptable, and Rosenstiehl proposed to represent benzene by the union of six carbon tetrahedra (59), the first of several variations on this theme (60). Wislicenus time and again, in several papers on the lactic acids (61),returned to the need for spatial representation, and wrote the preface for the German edition (62) of van't Hoff's La Chintie d a m 1'Espace (1875), thus incurring with van't Hoff the well known tirade from Kolhe on this "miserable speculative philosophy" (68). Wislicenus was instrumental in developing the chemical, as opposed to the physical, consequences of the van't Hoff-Le Be1 theory (64). As late as 1884 Crun~Bro~vn, always cautious in speculative matters, although acImowledging the importance of the work of Le Bel and van't Hoff, still termed it a "plausible theory" (G), j-et contributed to its theory six years later (66). Both Le Rel and van't Hoff realized not only the importance of the spatial arrangement of valenciea around carbon, but extended their thinking to include particularly certain aspects of isomerism that could not otherwise be satisfactorily explained except in terms of this theory. Van't Hoff's indebtedness to the work of Wislicenus was later acknowledged, and a t the saine time he mentioned that though he and Le Bel worked t,ogether in Wurtz' laboratory, they never discussed the tetrahedron (67). Later, van't Hoff commented: While engaged in studying the Wislicenus article on the lactic acids in the Utrecht library, I interrupted my perusal half a a y in order to go for a walk. I t was on this walk that through the influence of the fresh air the idea of the asymmetric carbon atom arose in me [681.
I n 1887, van't Hoff referred (69) specificall>-to three articles by Wislicenus (YO), and quoted him as easing: "Yacts compelled me to explain the diierence between isomeric molecules of the same structural forn~ulaeby the different position of their atoms in space" (68). Volume
44, Number 1 1 , November 1967
663
Van't Hoff's original statement on the asymmetric carbon atom is: The theory is brought into accord with the facts [regarding numbers of isomers predicted] if we consider the affinities of the carbon atom directed towards the oorners of a tetrahedron of which the carbon atom itself occupies the centre.. . When the four affinities of the carbon atom are satisfied by four univalent groups differing among themselves, two and not mare than two different tetrahedrons are obtained, one of which is the reflected image of the other, and they cannot be superposed; that is. we have here to deal with two structural formrtlas isomeric in space 1711.
Le Bel followed a line of thought from Pasteur and, inpendantly of van't Hoff, stated the same concept: Again if it happens not only that a single snbstitution [of MA.\ furnishes but one derivitive, hut also that two and even three suhst,itutions give only one and the same chemical isomer [there may he two optically active phgsieal isomers], we are obliged to admit that the four atoms A occupy the angles of s. regular tetrahedron, whose planes of symmetry are identical with those of the whole molecule MA4; in this cme also no hisubstitution product can have rotatory power.. . Further, as marsh gas never furnishes more than one derivative by two and three substilutians. . . [it is equivalent to MA41 . . . [(7t?)1.
Baeyer in 1885 advanced his theory that deviations from the normal valence angle of 109' in a cyclic mole cule cause strain in the molecule, and also included the statement that "the four valences are symmetrically distributed in space and correspond to spheres inscribed a t the summits of a regular tetrahedron" (73). At abont the same time Wunderlich deviated from the van't Hoff-Le Be1 theory and postulated a spherical carbon atom with four segments removed, the fonr flat circular faces heing in the planes of the faces of a regular tetrahedron ( 7 4 ) This arrangement is more akin to that of Butlerov ( i d ) , and the idea was developed further by Knoevenagel (75). The hypothesis of Hantzsch and Werner that nitrogen compounds have a tetrahedral arrangement, the nitrogen atom being a t one apex and the three valencies heing directed irregularly towards the other three corners (76) was objected to by Pickering: "The absurdity of the tetrahedron conception becomes more glaring when we pass from triad to pentad nitrogen compounds" (77), when a nitrogen atom and an hydrogen atom were considered to be tetrahedrally surrounded by four hydrogen atoms. The terms tn'ad and pentad, corresponding to trivalent and pentavalent, originate with Odling (78) and Frankland (79), Pickering suggested a planar molecule for ammonia, but a three dimensional arrangement for the nonexistent pentavalent nitrogen compounds. Ammonia does have a pyramidal arrangement with the nitrogen and three hydrogen atoms at each of the four angles, but it is better to consider the nitrogen atom at the centre of a tetrahedron with the three hydrogens and the unshared pair of spa electrons occupying the fonr corners. Pentavalent nitrogen is no longer accepted, nitrogen being considered to have a maximum valency of four, as in the ammonium ion. Werner considered that affinity originated a t the centre of a spherical atom and was directed uniformly towards all parts of the surface, resulting in a tetrahedral arrangement of the four hydrogen atoms ahout carbon in methane, and similarly in other carbon compounds (SO), because of the symmetrical arrangement abont the central atom. This is an interesting example of what Kapp has since called the Principle of Minimum Assumption (81). 664
/
Journal of Chemicol Educofion
An interesting further use of this geometrical figure in chemistry is the development of a modiied type of Prout's hypothesis ( S t ) by Ashe, who suggested a primordial linear element put together in tetrahedra, as well as other geometrical shapes (83). Farrar has r e cently shown that speculation on the composite nature of the elements was quite common during the nineteenth century (84),and Brock and Knight have discussed the scepticism of the existence of the atoms themselves dnring the same period (85). Until the end of the eighteenth century much effort was directed towards determining the reasons for cohesion between particles, without having any clear conception of the particles themselves. The acceptance of the Daltonian concept of the atom, and the shift in emphasis away from the causes of cohesion directed attention to the arrangement of atoms in the molecule. The establishment particularly of the tetravalence of carbon left a limited choice in organic chemistry for the manner of the arrangements of these valencies around the central carbon atom, and the tetrahedral concept was not slow to emerge, being consolidated by its ready ability to explain the optical properties of certain carbon compounds. Summary
The tetrahedron has played five major roles in chemistry: Tetrahedral shape ofmolecules: Bernoulli (169O), Haiiy (1784), Thomson (1801, 1802) ~etrahedralarrangement of four atmns: Hooke (1665), Boscovich (1758), Lomonosov (1760),Ampere (1814) Tetrahedral arrangement of four atoms about a fifth: Wollaston (1808),Butlerov (1862),Gaudin (1865), KekulB (1867),Paternh (1869),van't Hoff and Le Be1 (1874),Baeyer (1885),Werner (1891) Tetrahedral shape ofatoms: Wallerius (1763),Butlerov (1862),Wunderlich (1886) Tetrahedral inner arrangement of the atom: Boscovich (1758),Ashe (1889) Literature Cited
(1) For example, Laaowsq J. J., "The Chemical Band, Classic Researches in General Chemistry," Honghton MifAin Company, Boston, 1966; BEN? H. A,, "The Tetrahedral Atom," Chemistry, 39(12), 8-13 (1966); ibid.,40(1), 8-15 (1967). (2) KEKWL~, A., Ann., 104, 133 (1857). (3) KEKULB,A., Ann., 101, 200-13 (1857); KOLBE,H., (AND E.), Ann., 101,256-65 (1857); ODLINQ, W., FRANKLAND, PTOC. Roy. Inst., 2.63 (1858), read 1855. (4) KEKUL~, A., Ann., 106, 129-59 (1858). ( 5 ) COWPER, A. S., Phil.Mag., (4), 16, 104-16 (1858). (6) For good accounts of the development of stereochemistry see, for example, B~scnom,C. A., "Hsndhuch der Stereochemie," Frankfurt, 1894; Bunov, G. V., "Istoriia Stereokhimii Orgsnischeskikh Soedinenii:" (History of the Stereochemistry of Organic Compounds), USSR Academy of Sciences, Moscow, 1966. (7) KEKUL*,A,, "Lehrhuch der Organischen Chemie," Erlansen 1185941). vol. LDD.157-8. 162: 1866. vol. 2. D. 515.
MARKOVNIKOV, V. V., Z this, with refs. (8)and (9) are reprinted in "Centenary of the Theory of Chemical Stmcture. Collection of Papers by A. M. Butlerov, A. S. Couper, A. KekulB, and V. V.
Markovnikov," edited by B. A. Kaxansky and G. V. (42) PABTEUR,L., Lepons p m f e s s k A la Soci6t6 chimique do Bykov, USSR Academy of Sciences, Moscow, (1961), Paris le 20 ianvier et le 3 f6vrier 1860: in "Oeuvres de with commentary by G. V. Bykov. Pasteur," eiited by P. VALLERY-RADOT, Masson et Cie., 1022 vol. 1. n . 327. (12) MEYER,L., "Die Modernen Theorien der Chemie," 1864, -Pnria ----7 -. -. p. 76. (43) PASTEUR, "Oeuvres," op. cil., vol. 1, p. 330. (44) PASTEUR, L., Cmpte rendus, 31, 480 (1850); in "Oeuvres," (13) GAUDIN, M. A. A., Ann. Chim., 52, 113 (1833). op. cit., val. 1, p. 121. (14) BUTLEROV, A. M., Uchenye aapiski Kazanskogo univerJ., Ann., 128, 46 (1863). (45) WISLICENUS, siteta, (Notes of Kazan University), (1862), vip. 1, otd. (46) C A R ~ SL... Ann.. 130. 240-1 (1864). 1, p. 13; in Butlerov, A. M., "Sochineniia," (Works), (47) BAYMA,' .J.,'Proe. R O ~ .'&c., 13; 126 '(1864). USSR Academy of Sciences, Moscow, 1953, vol. 1, p. 76. (48) GAUDIN,M. A. A., "R6forme de la Chimie minerale et (15) BUTLEROV, A. M., Z. j. Chem., 5, 299 (1862). organique et de la Morphog6nie molkculsire et de la (16) Ibid., 4, 556 (1861). CristallogAnie s u moyen de la Mhcanique des Atomes ou (17) See, for example, BAILEY,C., "The Greek Atomists and Epicurus," Clarendon Press, Oxford, 1928; PARTINGTON, Synth6se MathBmatique," Paris, 1865, p. 16. (49) ~ A N ' T HOFP, J . H., "Dix Ann6es dsns 1'Histoire d'une J. R., "The Origins of the Atomic Theory," Ann. Sci., 4, 24542 (1939). Theorie," Rotterdsm, 1887, pp. 2 3 4 . (50) GAUDIN,M. A. A,, "L'Architecture du Monde," Paris, (18) DA~IDSON, W., "Les Elemens de la Philosophie de I'Art du 1873. Feu on Chemie," Paris, 1651, pp. 627-9; trans. by Jean (51) KEKULB,A., Z. f. Chem., 10,218 (1867). Hellot from the Latin original (1633-5). The title page (52) GILLIS,J., Mededelingenuande koninklijhe Vlaamse Acdulnnie includes the words "par une verit6 fond6e sur une necesVOOT Wetenschappen, 20, 3 (1958). sit6 Geometrique, & demonstr6e & la manibre d7Euclide!' (53) KEKULB,A,, Ber., 2,654 (1869). Pierre Gassendi considered atoms of cold or cooling atoms (54) DEWAR,J., Brit. ASS.Rep., ii, 36 (1869), read 1868. (atomos frigoris, aut jrigorijicm) to have s tetrahedral (55) DALTON,J., "On the Phosphates and Arseniates.. .and a shape: Physicae, see1 I, lib. VI, cap. VI, in Opwa Omnia, New and Easy Method of Analysing Sugar," Manchester, Florence, 6 vols., (1727), edited by C. N. Averanio, 1840-2, last sect., p. 3; in Partington, J. R., "A Hisvol. 1, p. 349. tory of Chemistry," Macmillan and Co. Ltd., London, (19) BERNOULLI,JOHANN,"Dissertatio de effervescentia et 1962, val. 3, p. 780. fennentatione nova hypothesis fundata," Basle, (1690); (56) Biogrs,phi.phioal details, with port., in POPE,W. J., J. Chem. ''Opera Omnis," Lausanne, (1742), i, pp. 1-44; in Soc., (1937), 1813. MILUNGTON,E. C.,"Theories of Cohesion in the Seven(57) PAT ERN^), E., Gazz. Chim., 23, 36 (1893), quoted from the teenth Century," Ann. Sci., 5,268 (1945). original in PATERN&E., Giornale di Sn'errre neturali ed (20) THOMSON,T., "Encyclopedia Britannica. Supplement," Ewnmiche, (Palenno), 5, 117-22 (1869). Edinburgh, 1801,vol. 1, i, p. 343. (58) K E K U L ~A,, , Bull. Sac. Chim., 3, 100 (1865), for the closed (21) THOMSON, T., "A System of Chemistry," Edinburgh, 1802, chain graphic formula; Bull. A d . Roy. Belge., (2), 19, vol. 3, pp. 147-8. 55143 (1865), for the hexagonal formula; "Lehrbuch (22) Ibid., (3rd Ed.), 1807, vol. 3, pp. 424-9. der Organischen Chemie," Edmgen, 1866, vol. 2, p. (23) DALTON,J., "A New System of Chemical Philosophy," 496, for the alternate douhle and single bond hexagonal (2nd Ed.), London, 1842, Part 1, pp. 21&1. However, formula. among diagrams prepared for Dalton's lectures, probably (59) ROSENSTIEHL, A,, Bull. Sac. Chim., (2), 11,394 (1869). in 1810-1815, there is s tetrahedral arrangement of the (60) For example, MARSH,J. E., Phil. Mag., (5), 26,426 (1888); four atoms of oxamide, CHON, (GEE,W. W. H., COWARD, T . o s c n n t-~ ~.T.. -..~,. Monatseh.. 11. 28 (1890): .. ERLENMYER. H. F., AND HARDEN,A., Manchester Memoirs, 59, no. JR., F.G.c.E., Ann.,316, i 7 (igoi). 12, p. 42, plate VII (1914-15)). (61) WISUCENUS, J., Bm., 2, 551, 620-1 (1869); 4, 523 (1871); (24) BOYLE,R., "The Origine of Fonnes and Qualities," (2nd Ann., 166,364 (1873); 167,30246,34656 (1873). Ed.) London, 1677, pp. 123.126. (62) VAN'THOFF,J. H., "Die Lsgerung der Atome im Raume" (25) Ibid., pp. 130-1. (trans. by F. Hennsnn, Braunschweig), (1877), preface (26) See, for exsmple, BURKE,J. G., "Origins of the Science of by wisliienus. Crystals," University of California Press, Berkeley and KOLBE,H., J. Prakt. Chem., (2), 15, 473 (1877); excerpts Los Angeles, 1966; METZGER,H., "La Genbse de 1s G. W., "Advanced Organic translated in WHELAND, Science des Cristaux," Felix Alcan, Paris, 1918. Chemistry," (3rd ed.), John Wiley & Sons, Inc., New (27) WLLLEEIUS,J. G., "Minerdogie," Berlin, 1763, pp. 164-5. York, 1960, pp. 197-8. J., J. f. Chem. u . Phys. van Gehlen, 8, 370 (28) BERNHARDI, J., "Uher die riumliche Anordnung der Atome WISLICENUS, (1809); in BURKE,op. eit., p. 167. in organischen Molekulon und ihre Bestimmung in (29) HOOKE,R., "Micragraphia," London, 1665, p. 47; facsimile geomelrisch-isomere, ungesiittigten Verbindungen," Ues edition in "Early Science in Oxford," edited by R. T. XIV Bandes der Ahhandlungen der mathemaiischGunther, vol. 13, (14 vols., Clarendon Press, Oxford, nhvsischen Clssse der KBniel. Siichsischen Gesellschaft (1923-1945)). der Wissenschaften, Leipsig, (1887); see also the Wis,, (30) HOOKE, op. cif., pp. 8 5 4 . licenus Memorial Lecture by W. H. PERKIN,JR., (25 Jan. 1905), in "Memorid Lectures delivered before the (31) LIPSON,H., AND BEEVERS,C. A., PTOC.I?.oy. SOC.,A, 148, Chemiesl Society, 1901-1913," Gurney and Jackson, (1935). 665 (1935): LIPSON.IT..ibid... 151,347-50 . London, 1914, vol. 2, pp. 59-92. (32) Edition cited is "A Theory of Natural ~ h i l o s o ~ h R. ~ , "J. Edin. Math. Soc. Proe., 2, 28 (1884). (65) BROWN, A. CHUM, Boscovrc~,Latin-English edition, translated by J. M. (66) BROWN, A. CRUM,Pmc. Roy. SOC.Edin., 17, 181-5 (1890). Child from the third edition of 1763, Chicago and London, (67) VAN'THOFF,J . H., "The Arrangement of Atoms in Space," (1922). See also "Roger Joseph Boscovich, S.J., F.R.S., (2nd ed.), London, 1898, p. 2, translated from the 1894 1711-1787, Studies of his life and work on the 250th. edition by A. Eiloast. Anniversary of his birth," edited by L. L. Whyte, London, (68) COHEN,E., "Jambus Henricu~van't Hoff," Akademiche George Allen and Urlwin Ltd. (1961). Verlagsgesellschaft, Leipzig, 1912, ? 85; in 0 . T. Ben(33) B o s c o v ~ cop. ~ , cit.. sect. 7, p. 37. fey's int,roductian to his translat~on of van't Hoff's (34) Ibid., sect. 398, p. 287. inmgural address, (1878), "The Role of Imagination (35) Ibid., fig. 1, p. 42. in Science," J. CHEM. EDUC., 37, 467 (1960). The (36) Ibid.. sect. 239. D. 187. English translation of the presentation speech for the (37j w O L L ~ T O N , w.H., P M . yVmns.,98,102 (1808). first Nobel prize in Chemistry, to van't Hoff in 1901, (38) Ibid., (18131, pp. 60-1. incorrectly infers that he fallowed a line of thought from 139) BAUDRIMONT. A. E.. "Trait6 de Chimie G&nCrale et Eso6riPasteur: "Nobd Lectures in Chemktry, 1901-1021," mentale," Paris, 2 vols. 1844-6; vol. 1, p. 9. Elsevier Publishing Co., Amsterdam-London-New York, (40) AMPBRE,A.-M., Ann. Chwn., 90, 4 P 5 (1814); trans. UI 1966, p. 3. Phil. Mag., 45.42 (1815). (69) VAN'T HOFF, J . H., "Dix Ann6es dans I7J5istoire d'une (41) Ibid., Phil. Mag., pp. 109-110. Theorie," Rotterdam, 1887, p. 24.
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(70) WISLICENUS, J., Ann., 166,3; 167,302, 346 (1873). ( i l ) V . ~ ' THOFP, J. H., "Yoorstel tot uitbreiding der tagenwoordig in de scheikwlde gebruikte struct,,wrformules i n de ruimte, ete.," Utrecht, 1874; translated in "Classim
in the Theory of Chemical Combination," edited by 0. T. BENFEY, Dover. Publimtions IIIC., New York, 1963, p. 152, from "Foundetioos of Stereochemistry. Memoirs by Pasteur, van't llotl, Le Be1 and Wislicenus," trans. and edit. by G. 1\4. Richardson, New Yark, 1901. (i?) LE BEI., J. A.. Bull. Soe. Chim., (2), 22, 33747 (1874); translated in BENFEY,op. cil., p. 163. (73) BAEYER, A. von Be?., 18,2277 (1885). (74) WuN~EnLlcn,A,, "Configuration orgsniseher Mulekde," Waraburg, 1886; nhstr. in Ber., 19,592R (1886). (75) KNOEVENAGEL, E., Ann., 311,194-240 (1900). (i6) HANTZSCH, A,, IKD WERNER,A,, Ber., 2 3 , l l (1890). (7i) PICKERING, S. U., J. Chem. Soc., 63,1069 (1893). (78) ODLING,W., "Tables of Chemical Formulae," 1864. (i9) FR\NKLAND, E., J . Chem. Soe., 19,372-95 (1866).
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(80) WERNER,A,, Vierteljahrssehrift der Ziiricher naturforscheilden Gessellsehaft, 36, (1891). (81) KAPP,R. O., "Towards B Unified Cosmology," The Seientific Book Guild, London, 1962, pp. 32 et passim; see
also, LARDER,D. F., "The Axiom of Simplicity in the Development of Chemistry," J. CHEM. EDnc., 43, 491 (1966). (82) See, for example, LARDER,D. F., "Prout's Hypothesis and Nineteenth Century Chemistry," Educ. C h m . , 2, 2714 (1965); on Prout see particularly BROCK,W. H., Aced. Hisl., 9, 101-26 (1965); also BROCK,W. H., J. CHEM. Eouc., 40, 652 (1963); SIEGFRIED,R., ibid., 33, 263 (1956); BENFEY,0. T., ibid., 29, 78 (1952); GLASSTONE, S., ibid., 24, 478 (1948). (83) ASKE,I., Chem. News, 60,235 (1889). (84)F.4~ll.4~~ W. V., B d . J . Hist. SC., 2 , part IV, 297-323 (1965); see also SCOTT, J. H., J. CHEM.EDUC.,36, 64-7 (1959). (85) Bnocs, W. IT., A N D KNIGHT,D. XI., I S ~ S56, , 5-25 (1965).
