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London, Thomas Parkhurst, 1674. 8vo. In contemporary full calf with double ruled fillets to boards. Small paper-label pasted on to top of spine. Wear to extremities, leather cracked and boards with scratches. Inner hinges partly split but bookblock firmly attached. Internally with a few doodles in contemporary hand. (24), 388, (10), 31, (8) pp. Rare first edition of Whitaker’s eighteen sermons which had been taken in shorthand and published by his widow, with a dedication to Elizabeth, countess of Exeter. William Whitaker (1629–1672), a Puritan divine, entered Emmanuel College, Cambridge, at fifteen, where he distinguished himself in classical and oriental languages. He earned his B.A. in 1642. Two years later, he became a fellow of Queens' College by parliamentary ordinance and received his M.A. from the same institution in 1646. In 1652, he was ordained and became the minister of Hornchurch, Essex. He succeeded his father as rector of St. Mary Magdalen, Bermondsey, in 1654. Whitaker was one of the London ministers who petitioned the king against the Act of Uniformity's oppression.

La Haye, P. de Hondt, 1753. 4to. In contemporary half calf with five raised bands. Small paper-label pasted on to top of spine. Light wear to extremities. Ex-libris pasted on to pasted down front end-paper. Internally nice and clean. XII, 585, (3) pp. + 15 folded maps and plates (complete). Rare and finely illustrated 10th volume of Prevost’s extensive work on various travel accounts which cover numerous travel narratives to different parts of the world, documenting the discoveries, explorations, and adventures of travelers.This present 10th volume contain descriptions of Tartars, Tibet, Bukhara (Uzbekistan), China, India, Maldives, Batavia and Malakka with maps and plates to illustrate these areas. This present Hondt-edition is “Mainly a reprint of the Paris edition, but with many corrections and additions, especially in the later volumes. The maps and plates were finely engraved by J. van der Schley.” (Sabin 65404). According to Tchemerzine this the best edition.The first edition was published in Paris in seven volumes between 1744 and 1747. This present edition was published in 25 volumes between 1747 and 1780.Sabin 65404Tchemerzine IX, 233: ("C´estla meilleure édition de ce recueil")

8vo. Bound in 3 cont. hcalf. Volume 1 with 2 small holes in back and a little loss of leather on frontcover along first hinge. Gilt backs, a little rubbed. (4),488,(4),480,(4),427 pp. Ocassionally a little brownspotted and some margins slightly dampstained. With 150 engraved plates (not colored). Nissen No 2345.

Oslo, 1937-86.

Odense, Biering, 1776. 8vo. In contemporary half calf with four raised bands. Small paper-label to top of spine. Light wear to extemities, boards with scratches. Dampstain to first few leaves, otherwise internally clean. Printed on good paper. (8), 408 pp. OCLC only list one copy (Copenhagen, Royal Danish Library). Biblioteca Danica IV, 251

Leipzig, Barth, 1901. 8vo. Bound in full black cloth with gilt lettering to spine. In "Annalen der Physik", Vol. 6, 1901. Entire volume offered. Library labels pasted on to front end papers, stamp to title page, otherwise a fine copy. Pp. 433-58. [Entire volume: VIII, 876 pp. + 3 folded plates]. First appearance of the account of Lebedev's seminal experiment proving that light exerts a mechanical pressure on material bodies thereby confirming Maxwell's electromagnetic theory for the very first time - a landmark discovery in modern physics. James Clerk Maxwell "made an important new prediction from his electromagnetic theory-that electromagnetic waves exert a radiation pressure. Bright sunlight, he calculated, presses on the earth's surface with a force of around 4 pounds per square mile [...] This was too tiny a value to be observable in everyday life and its detection posed a challenge to experimenters. Eventually, in 1900, the Russian physicist Pyotr Lebedev succeeded, and confirmed James' prediction. Although small on an earthly scale, radiation pressure is one of the factors that shape the universe. Without it there would be no stars like our sun. [The] discovery also helped to explain a phenomenon that had puzzled astronomers for centuries-why comets' tails point away from the sun" (Mahan, The Man who Changed Everything: The Life of James Clerk Maxwell, 183)."As early as 1891 Lebedev became seriously interested in the pressure of light. He turned his attention to the fact that since the force of gravity is proportional to the volume of a body whereas light pressure must be proportional to its surface, it may be asserted that in a particle of cosmic dust the forces of light pressure pushing the particle away from the sun will be equals to the force of gravity attracting it toward the sun. Lebedev used this theory to explain why comets'tails always point away from the sun. His hypothesis was considered correct until the discovery of the solar wind, which creates substantially greater pressure than the sun's light.Around 1898, Lebedev began experimental research on light pressure. Although its presence had been predicted by Maxwell's theory, it had not been detected experimentally before Lebedev. He first undertook research on the pressure of light on solid bodies. Because of the weakness of the effect itself and the considerable number of possible side effects, this experimental problem presented very great difficulties: if a body that is supposed to react to light pressure is placed in a gas, the warming of the body by the light will inevitably cause convection currents and thus set the body in motion. If the body is placed in a vacuum (in practice, in gas at very low pressure), the so called radiometric effect will occur. As a result of the uneven warming of the front and back of the body, the molecules of gas hitting the body from the front will be repulsed more forcefully than those striking the back, thereby exerting greater pressure. By extremely ingenious methods Lebedev succeeded in completely eliminating these side effects and not only detected the pressure of light but also measured it and showed the correctness of Maxwell's quantitative theory. "Opytnoe issledovanie svetovogo davlenia"("An Experimental Investigation of the Pressure of Light") was read by Lebedev at the International Congress of Physicists at Paris in 1899 and was published in 1901." (DSB)

Jena, Christian Henrich Cuno, 1751. 4to. Contemp. hcalf. Raised bands. Compartments tooled in blind. Titlelabel with lettering. A paperlabel pasted on spine. With the monogram of Frederik V on red background on covers. Stamp on foot of title-page. Title-page in red/black. (12),196,(8) pp., 31 folded engraved plates. First edition.

London, Macmillian & Co, 1961. Royal8vo. Bound in contemporary half cloth with gilt lettering to spine. In "Nature" Vol. 192, October - December, 4797-4809, 1961. Entire volume offered. A stamp on title page. A fine and clean copy. Pp. 1227-1232. [Entire volume: CVII, 1322 pp.]. First printing of this seminal paper in which they described a very elegant series of genetic experiments by which they proved that the genetic code for protein was a triplet code. "In February 1961, Crick began a series of experiments based on an idea he had about the manner in which a mutation can be "suppressed" by a further mutation. The results led him to support Brenner's suggestion that such "suppressions" are due not to substitution of a different base in a sequence of bases on the DNA molecule, but to addition or deletion of a base. After conducting extensive experiments for some five months, Crick attended a meeting in the Alps. There he mentioned this idea, and the hypothesis "that the code is read in short groups, starting from one end of the gene. The exact starting point is supposed to determine which group is read" (Crick, 1961a, p. 188).Back in Cambridge Crick carried out further experiments to clinch the case for the "short groups" being composed of three bases or a multiple thereof. In their classic paper summarizing this work, the Cambridge group claimed that the genetic code "is of the following general type": three bases (or a multiple of three) codes for one amino acid. It is not an overlapping code, "probably 'degenerate'; that is, in general, one particular amino-acid can be coded by one of several triplets of bases," and "the sequence of the bases is read from a fixed starting point.… There are no special 'commas' to show how to select the right triplets" (Crick et al., 1961, 1227)." (DSB) Garrison-Morton.com 752.7. Norman 534

Kjøbenhavn, Reitzel, 1834-40. Lex8vo og folio. 1.-5. Bd. indbundeti 3 samtidige hldrbd. Rygge lidt slidte. (Alberti's navnetræk i 5. bd.). Fortsættelsen (folio) 1.-2. Halvbd. i 2 samtidige hshirtbd. Rygge lidt slidte. 704,928,932,920,1104 spalter + 3152 spalter (minus de anførte numre).Alle bind med orig. titelblade og indholdsfortegnelser. Fædrelandet blev den førende avis i kampen for en fri forfatning, især da den i 1840'erne inddrog nationalitetskampen i Slesvig og dermed de nationalliberale synspunkter ("Danmark til Ejderen!") i sit journalistisk-politiske program. Fædrelandet blev en avis for eliten med sine tunge, polemiske artikler i akademisk stil og svage nyhedsdækning. Avisen udkom til og med 1882, Carl Plough var redaktør fra 1841.Redaktøren C.N. David blev anklaget efter Trykkefrihedsforordningen, da juristen Orla Lehmann i 1834 på avisens forside skrev om de nye stænderforsamlinger (indført 1832) som et første skridt til folkestyre. Han blev senere frifundet. (Avisnet).En avis for eliten med sine tunge, polemiske artikler i akademisk stil og svage nyhedsdækning.

[No place], 1953. 8vo. In the original printed wrappers. Offprint from "The Philosophical Review", Vol LXII, No. 2, April 1953. Author's presentation inscription to verso of front wrapper: "To Prof. Jørgensen, / With personal regards, / M. Weitz". Previous owner's book plates to verso of front wrapper [Carl Henrik Koch]. Light miscolouring to front wrapper and a few marginal underlignings throughout, otherwise a fine copy. Pp. 187-233. Scarce offprint issue with author's presentation inscription of this influential and famous work which is widely regarded as being the work that introduced the then developing Oxford school of philosophy to the American audience. Morris Weitz was an American aesthetician and philosopher. He received his doctorate from the University of Michigan. During the course of his career he taught at Vassar College, at Ohio State University and at Brandeis University. Weitz was one of the first philosophers to recognize the difficulty posed for philosophy of art by the rapid proliferation of art movements in the twentieth century, from modernism to dadaism. If the "readymades" (a urinal, a snow shovel, a bottle rack, etc.) of the avant-garde artist Marcel Duchamp (1887-1968) could count as art, then traditional conceptions would have to be revised. Weitz proposed that all that binds together the disparate products called "art" are loosely connected "family resemblances," a notion drawn from Ludwig Wittgenstein's Philosophical Investigations (1953). (New Dictionary Of The History Of Ideas, p. 16)

Paris, Crochard, 1821. Contemp. hcalf. Spine gilt with tome-and titlelabels with gilt lettering. Wear to top of spine. A crack along first hinge, but cover not loose. In 'Annales de Chimie et de Physique', Volume 19. (Entire volume offered). 448 pp. a. 2 plates. Navier's paper: pp. 244-260. A faint dampstain to margins of the first 20 leaves and a bit seen on the following pages, decreasing. First appearance of Navier's famous paper in which he describes the relations between fluid flow and friction, giving the FUNDAMENTAL EQUATIONS OF THE MATHEMATICAL THEORY OF ELASTICITY. The full paper was not published until 1828. Stokes's analysis of the internal friction of fluids was published in 1845, and as he was not familiar with the French litterature of mathematical physics, he derived independently his own equations, which accounts for the double-name of the equations. "The Navier-Stokes equation is now regarded as the universal basis of fluid mechanics, no matter how complex and unpredictable the behavior of its solutions may be. It is also known to be the only hydrodynamic equation that is compatible with the isotropy and linearity of the stress-strain relation." (Olivier Darrigol)."Navier studied the motion of solid and liquid bodies, deriving the partial differential equations to which he applied Fourier's methods to find particular solutions. This theoretical research led him to formulate the well-known equation identified with his name and that of Stokes. Navier viewed bodies as made up of particles which are close to each other and which act on each other by means of two opposing forces - one of attraction and one of repulsion - which, when in a state of equilibrium, cancel each otherout. The repelling force resulted from the caloric that a body possessed. When equilibrium is disturbed in a solid, a restoring force acts which is proportional to the change in distance between the particles."(DSB, X, p. 4)."The equations are useful because they describe the physics of many things of academic and economic interest. They may be used to model the weather, ocean currents, water flow in a pipe and air flow around a wing. The Navier-Stokes equations in their full and simplified forms help with the design of aircraft and cars, the study of blood flow, the design of power stations, the analysis of pollution, and many other things. Coupled with Maxwell's equations they can be used to model and study magnetohydrodynamics. "(Wikipedia).

Kiøbenhaffn, Georg Lamprecht Paa Joachim Moltkens bekostning, (1650-)55. Folio. 2 meget velbevarede danske spejlbind fra midten af 1700-tallet, overdådig rygforgyldning, forgyldte titel-og tomefelter. Blindtrykte bordurer og forgyldte bordurer på permer. Marmoreret snit. Kobberstukket titelblad stukket af Greys (10),(8),841,(6),114,(54) - (11),842-1555 pp. samt Registre til begge bind. Indvendig ren med få spredte brunpletter. Kobberstikket af Huitfeldt og kongetavlen mangler. Eksemplaret her er trykt på godt papir L. Nielsen beskriver i "Den Danske Bog" værket som dårligt trykt på slet papir. Ovenstående eksemplar er et af de få eksemplarer trykt på bedre papir.Thesaurus, 498.

London, Harrison and Sons, 1923. Royal8vo. Contemp. full cloth, gilt lettering to spine. A small stamp to verso of titlepage and on foot of a few leaves.. In: "Proceedings of the Royal Society", Series A, Vol. 104. VI,(6),676,XXXII pp., textillustr. and plates. (Entire volume offered). Wilson's papers: pp. (1-) 24 and 12 plates + pp. 192-212 and 9 plates. First printing of the paper in which Wilson had brought his Cloud Chamber to perfection and showed the photographic tracks of the particles. The Cloud Chamber was the first detector of radioacticity and nuclear transmutations and it played an importent role in experimental particle physics e.g. the discovery of the positron. Wilson received the Nobel prize - together with Arthur Compton - in physics in 1927 for his work on the Cloud Chamber."The 21 cloud chamber pictures of X-rays and beta-rays on coated stock printed recto only were the culmination of many years research by Wilson and at last showed the full potential of this method as a tool for particle physicists. Early in 1911 (Wilson) was the first person to see and photograph the tracks of individual alpha-particles and electrons. The event aroused great interest as the paths of the alpha-particle were just as W.H. Bragg had drawn them in publication some years earlier. But it was not until 1923 (the paperoffered) that the clous chamber was brought to perfection and led to his two, beautifully illustrated classic papers on the track of electron." (The Nobel Foundation).

Ultrajecti (Utrecht), Meinardi à Dreunen, 1658. 8vo. Contemporary full vellum. Spine wide as another work has been taken out of binding ?. (24),255,(1) pp. Internally clean. Scarce first edition of Leusden's Syrian Grammar.

Leipzig, Johan Ambrosius Barth, 1891-93. 2 orig. full decorated cloth. Very light wear to spine ends. XII,189;VIII,160 pp. and 4 plates (2 large folding) and textillustr. Clean and fine. On both front free endpaper the previous owners names, the two famous physicists Walter Makower and Aage Bohr 1945. First edition of one of Boltzmann's main works. "In the 1890’s Boltzmann again revived his interest in electromagnetic theory, perhaps as a result of Hertz’s experiments, which he repeated before a large audience in Graz. He published his Vorlesungen über Maxwells Theorie in 1891 and 1893, along with some papers in which he suggested new mechanical models to illustrate the field equations." (DSB).Walter Mackower, a research student under Thomson effected his transformation into a physicist, and his M.A. was for a thesis on the diffusion properties of radium emanation (radon). He later worked with Rutherford, Geiger, Rush and Fajans and he did pioneering research on radioactive substances and radioactive recoil.Aage Bohr, son of Niels Bohr, was awarded the Nobel Price in physics jointly with Mottelson and Rainwater in 1975 "for the discovery of the connection between collective motion and particle motion in atomic nuclei and the development of the theory of the structure of the atomic nucleus based on this connection".

(No place), The Association for Symbolic Logic, 1959. 8vo. Wrappers blank with printed title on spine. Entire issue No. 1 of vol. 24, offered. Fine and clean. The seminal first printing of Kripke's debut article, which provided the basis for his logic and for the model theory for modal logic in general. The work constitutes the very beginning of Kripke Semantics (often called possible world semantics). Kripke's works in general are rare in fist editions. Many of them remain unpublished and are only known in privately circulated manuscripts.The American philosopher Saul A. Kripke (born 1940) is an exceedingly important logician and philosopher of language and one of the most powerful and influential thinkers of analytic and Anglo-American philosophy. He is considered the greatest living philosopher and perhaps the greatest since Wittgenstein. In 2001 he was awarded the Schock Prize in Logic and Philosophy, which is considered the philosopical equivalent of the Nobel Prize.Kripke, who grew up in Omaha in a religious Jewish family, was somewhat of a prodigy child. During grammar school he got intimately acquainted with and mastered to perfection algebra, geometry and calculus, and very early on he took up philosophy, which later became his career. Still a teenager, in high school, he wrote a work that was to change the face of philosophical logic forever, namely the groundbreaking paper "A Completeness Theorem for Modal Logic", which was printed a few years later, in 1959, in the Journal of Symbolic Logic, while he was in his first year at Harvard University. This seminal debut work proposed what later came to be known as Kripke models for modal logic. The story goes that the paper earned a letter from the department of mathematics urging Kripke to apply for a job there, to which he is said to have written an answer explaining "My mother said that I should finish high school and go to college first."In 1962 he graduated from Harvard University, where he remained until 1968, first as a member of the Harvard Society of Fellows and then as a lecturer. During these years he developed the logical theories founded in the "Completeness Theorem" further and made seminal contributions to the field of logic and semantics. Kripke Semantics is a formal semantics for non-classical logic systems that Kripke began developing in his teenage years, first published something on in 1959 (the present work) and further developed in the 60'ies and. The development of Kripke Semantics was no less than a breakthrough in the making of non-classical logics, of which no model theory existed before Kripke's. With this work, Kripke laid the foundation for proving completeness theorems for modal logic, and for identifying the weakest normal modal logic, which is now named K after him.

Danzig, Kosten des Verfassers, 1852. 8vo. a. folio. 2 contemp. hcalf. Gilt spines. A paperlabel pasted on upper part of spines. Stamps on title-pages. (8),184,(2) pp. and 1 lithographed plate. Atlas with 22 (on 21) large lithographed plates, many double-page and folding. Some scattered brownspots. First edition. The original printing.

Kiøbenhavn, L.H. Lillie, 1756. Samtidigt hldrbd. Let ophøjede bind på ryggen. Titeletiket med forgyldning. Øverste kapitæl nænsomt restaureret. Kobberstukket titelvignet visende et kildespring. (24),134,(1) pp., 1 udfoldelig tabel og 2 udfoldelige kobberstukne plancher, visende vanddyr. Trykt på svært skrivepapir. Lidt spredte svage brunpletter. Originaludgaven. Første egentlige undersøgelse af drikkevandsforsyningen til København, men også første danske beskrivelse af vandets småkrebs, daphnier og cyclops, som afbildes i bogen. - Lange trøster sine læsere med, at disse kan frasies med en pose af hvidt hattefilt, hvis De da ikke foretrækker at synke dem eller nyde suppen af dem når vandet er kogt.

Paris, Chez les Libraries Associés pour les Usages du Diocèse de Paris, 1781. 12mo. (15,5x9 cm.). Bound in an exquisite contemporary green full morocco binding with richly gilt spine and boards. Gilt title and five raised bands to spine. Gilt line- and floral borders to boards and inner dentelles. The inner dentelles consist of two stamps of which one is known from a signed Derome binding made for Louis XVI. Edges of boards and all edges gilt. Endpapers in pink moiré. (Presumably by Derome.). Gilt label ("Renouard Lainé") to pasted down front endpaper. Internally clean. (24),600,CCXL pp. A beautiful, well preserved unsigned binding, probably by the renowned French bookbinder Nicolas Denis Derome.

Kiøbenhavn, ved Mauritz Frydensberg (Trykt hos Berlingske Arvinger), (1760-64). 4to. Indbundet i to uensartede pæne samtidsbind. Første Deel i et pænt hellæderbind med rig tidstypisk rygforgyldning of fem ophøjede bind, Anden Deel i et pænt lettere restaureret halvlæderbind med fornyede titel- og tome-etiketter, rig tidstypisk rygforgyldning og seks ophøjede bind. Svage biblioteksstempler på titelbladene (Nysø Bibliotek). På foden af kobberstikkene er indgraveret "Stukket efter Originalen paa det Kongl. Kunstkammer i Kiöbenhavn Anno 1760 (og til 1763)". De 2 sidste er dog signeret, stukket af Lÿman. Ren og pæn indvendig. Med to store kobberstukne vignetter (det ene på titelbladet). (18),480;160 pp. + 17 konge- og dronningeportrætter. Nydeligt eksemplar af originaludgaven. Ganske sjælden i komplet stand som her. De usignerede kobberstik er 1. Chr. I - 2. Dronning Dorotheæ. - 3. Kong Johannis. - 4. Dronning Christina. - 5. Chr. II. - 6. Dronning Elisabeth. - 7. Friderich I. - 8. Hertugninde Anna. - 9. Dronning Sophia. - 10. Chr. III. - 11. Dronning Dorothea. - 12. Friderich II. - 13. Dronning Sophia. - 14. Chr. IV. - 15. Dronning Anna Catharina. - 16. Friderich den Tredie. - 17. Dronning Sophiæ Amaliæ.

London, Cruchley map Seller, (1833). (42,5 x 60 cm.) Fine engraved and handcoloured map of London. Updated to 1833. The street- indexes engraved in the margins. The map is in fine condition, plain and not folded.

Leipzig, B.G. Teubner, 1880. 8vo. Bound in a nice contemporary half calf with five raised gilt bands. Red leather title label with gilt lettering to spine. All edged gilt. In "Mathematische Annalen", Band 17, 1880. Entire volume offered. Corners with wear, otherwise a very fine and clean copy. Pp. 355-358. [Entire volume: IV, 576 pp.]. First printing of Cantor's important second paper of the landmark series consisting of a total of six papers which together constitute the foundation Theory of Sets (Mengenlehre) and Transfinite Set Theory. Cantor here introduces his new Set Theory with which he created an entirely new field of mathematical research and is widely regarded as being one of the most important mathematical conquests in the 19th century. "Cantor's second paper of 1880 was brief. It continued the bricklaying work of the article of 1879, and it too sought to reformulate old ideas in the context of linear point sets. It also introduced for the first time an embryonic form of Cantor's boldest and most original discovery: the transfinite numbers. As a preliminary to their description, however, Cantor introduced several definitions. He also pointed out that first species sets could be completely characterized by their derived sets." (Dauben, P. 80)Hilbert spread Cantor's ideas in Germany and praised Cantor's transfinite arithmetic as "the most astonishing product of mathematical thought, one of the most beautiful realizations of human activity in the domain of the purely intelligible". He is famously quoted for saying "No one shall expel us from the paradise which Cantor created for us". Bertrand Russel described Cantor's work as "probably the greatest of which the age can boast"."The major achievement of the "Grundlagen" was its presentation of the transfinite ordinal numbers as a direct extension of the real numbers. Cantor admitted that his new ideas might seem strange, even controversial, but he had reached a point in his study of the continuum where the new numbers were indispensable for further progress. Cantor had finally come to the realization that his 'infinite symbols' were not just indices for derived sets of the second species, but could be regarded as actual transfinite numbers that were just as real mathematically as the finite natural numbers." (Grattan-Guinness, Landmark Writings in Western Mathematics, Pp. 604-5).Dauben: (Cantor)1880d.

14 - 4 - [19]07. 1 page, 8vo. "Kjære Hr Harder! - De skal meget snart / høre fra mig. Jeg har ikke kunnet skrive / før. Min Hustru har været meget syg / de sidste Tre Uger, er bleven opereret / flere Gange. Desuden har vi af andre / Grunde ikke kunnet faa Tid at se ordentlig / paa Deres Ting. Paa Gensyn Deres / Carl Nielsen." Original handwritten letter from the most prominent Danish composer, Carl Nielsen (1865-1931), addressed to his friend and colleague Knud Harder (1885-1967). Letters from Nielsen's hand are of utmost rarity.

Wien, Braumüller, 1849. 8vo. Bound with the original printed wrappers in a recent card-board binding. Ex-libris pasted on to verso of front board. Wrappers browned and internally with occassional marginal brownspotting. 52 pp. The very rare first edition, posthumously published, of a series of three lectures given by Bernard Bolzano in 1816 at the University of Prague. Here Bolzano steps into the sociopolitical arena addressing the relationship between the Czech and German populations in Bohemia (then part of the Habsburg Empire). Remarkably progressive, Bolzano’s call for tolerance and his opposition to nationalist exclusivism was ahead of his time especially considering the later ethnic tensions in the region.

Berlin, Julius Springer, 1927. 8vo. In contemporary half cloth with gilt lettering to spine. In "Zeitschrift für Physik", Vol. 44. Entire volume offered. Stamp to front free end paper, otherwise a fine and clean copy. Pp. 455-472. [Entire volume: VIII,903 pp.]. First appearance of grounbreaking paper which was the first to explain the nature of the chemical bound using wave mechanics and thus explaining the forces active when atoms exchange electrons and creating molecules."In June, Heitler and London published their famous paper on the hydrogen molecule in which they showed the existence of a new kind of saturable, nondynamic forces, the so-called "exchange forces" of attraction or repulsion between like particles, and developed a schematic theory of the homopolar valence which eventually BROUGHT THE WHOLE OF CHEMISTRY UNDER THE SOVEREIGNTY OF QUANTUM MECHANICS. These results not only lent weight to the concept of like particles, they also showed that like particles may be indistinguishable, that is, may lose their identity, a conclusion which follows from the uncertainty relations or, more precisely, from the impossibility of keeping track of the individual particles in case of interactions of like particles. (Jammer in "The Conceptual Development of Quantum Mechanic", pp. 343 ff.).Parkinson "Breakthroughs" 1927 C.