Molecular reality

Nye, M.J. (1972) Molecular Reality A Perspective on the Scientific Work of Jean Perrin (Macdonald, London and, American Elsevier, New York). 

Perrin, J. (1909) Annales de Chimie et de Physique 18, 1. English translation by F. Soddy, Brownian Movement and Molecular Reality (Taylor Francis, London) 1910. 

On this, for the first half of the nineteenth century, see Rocke, Chemical Atomism and for the later period, M. J. Nye, ed., The Question of the Atom, and Molecular Reality A Perspective on the Scientific Work of Jean Perrin (London Macdonald, New York American Elsevier, 1972). 

Jean Perrin, Les atomes (Paris Alcan, 1913 4th ed., 1914), and its analysis in Nye, Molecular Reality,... 

Letter from Perrin to Einstein, 28 August 1919 Einstein to Perrin, 5 November 1919, Einstein Collection, Institute for Advanced Study, Princeton (now housed in Jerusalem), cited originally in Nye, Molecular Reality, n. 93, 177. See F. A. Lindemann, "Note on the Significance of the Chemical Constant and Its Relation to the Behaviour of Gases at Low Temperatures," Phil.Mag. 39 (1920) 2125, cited in M. Christine King and Keith T. Laidler, "Chemical Kinetics and the Radiation Hypothesis," Archive for History of Exact Sciences 30 (1984) ... 

See Nye, Molecular Reality, also Pierre Colmant, "Querelle a l lnstitut entre equivalentistes et atomistes,"... 

Two major discoveries in 1953 were of crucial importance in the history of biochemistry. In that year James D. Watson and Francis Crick deduced the double-helical structure of DNA and proposed a structural basis for its precise replication (Chapter 8). Their proposal illuminated the molecular reality behind the idea of a gene. In that same year, Frederick Sanger worked out the sequence of amino acid residues in the polypeptide chains of the hormone insulin (Fig. 3-24), surprising many researchers who had long thought that elucidation of the amino acid sequence of a polypeptide would be a hopelessly difficult task. It quickly became evident that the nucleotide sequence in DNA and the amino acid sequence in proteins were somehow related. Barely a decade after these discoveries, the role of the nucleotide... 

Finally Jean Perrin presented an extensive (97 pages) Rapport sur les Preuves de la R6alit6 Moleculaire in which he summarized his famous experiments on the Brownian motion of emulsion droplets suspended in a liquid and discussed the fluctuations, the determination of the elementary charge, the a decay of some radioactive nuclei, and the corresponding production of helium. The last section of the paper contains a comparison of the values of Avogadro s number deduced by completely different methods. The very satisfactory agreement between all these values provides the proof of molecular reality announced in the title of the paper.11... 

Near the equilibrium bond length qe the potential energy/bond length curve for a macroscopic balls-and-spring model or a real molecule is described fairly well by a quadratic equation, that of the simple harmonic oscillator (E = ( /2)K (q — qe)2, where k is the force constant of the spring). However, the potential energy deviates from the quadratic (q ) curve as we move away from qc (Fig. 2.2). The deviations from molecular reality represented by this anharmonicity are not important to our discussion. 

M. Kerker, The Svedberg and molecular reality an autobiographical postscript , Isis, 1986, 77, 278-282. 

If the Oxford symposium of January 1932 was inconclusive, deliberations of the Swedish Academy of Sciences were not. Langmuir s work, unlike Polanyi s, fit squarely into recent preoccupations in physical chemistry, including the Swedish physical chemist Theodor Svedberg s concern with establishing molecular dimensions and what came to be called molecular reality , i.e., a simple, visual kinetic-mechanical picture in physics and chemistry. [34] In the fall of 1932 the Swedish Academy announced that Langmuir would receive the 1932 Nobel Prize in Chemistry. The prize was awarded for his discoveries and investigations in surface chemistry , a new scientific specialty and, literally, a boundary science. [35]... 

Perrin, J., Brownian Motion and Molecular Reality. Taylor Francis, London, 1910. 

J. Perrin, Mouvement brownien et moleculaire culaire. Ann. chim. Phys. VIII 18, 5-114 translated by F. Soddy as Brownian Movement and Molecular Reality, Taylor and Francis, London. 

This disunified scene, may, of course, be temporary. Physics may be working towards a more complete and unified picture of molecular reality. What evidence is there for this On one argument, the requirement of universal coverage is built into the very practice of physics. Thus, Quine has it that if the physicist suspected there was any event that did not consist in a redistribution of the elementary states allowed for by his physical theory, he would seek a way of supplementing his theory. Full coverage in this sense is the very business of physics, and only ofphysics (1981,98). 

This is the program that must be adopted to be absolutely rigorous thermodynamically, and it is certainly important that workers in the field realize it. However, in the present writer s opinion, if this program were actually used by experimentalists, the severe price paid, in loss of contact with molecular reality inside the container, would far exceed the value of the last ounce of exactness gained. 

M. Kerker, Brownian Motion and Molecular Reality Prior to 1900 , J. Chem. Educ., 1974, 51, 764. 

While the above results are most encouraging, they are incomplete until we show evidence for the molecular reality of the picture in Figure 6. The efficacy of the cyclodextrin in protecting the excited phosphor can be demonstrated by comparing... 

Fortunately this is so, as the existence of the Brownian motion shows. The particles in certain colloidal suspensions fulfil the required conditions. Observation with the ultra-microscope leaves no doubt about their particulate character, and they are seen to be in a state of random motion, darting hither and thither in a manner which gives a vivid impression of irregular impacts first fi om one side and then from another. These impacts must come from other particles which are themselves invisible, so that the Brownian motion (once the technical difficulty of showing that it is not due to convection currents is overcome) is justly claimed to provide evidence of molecular reality. 

Whether consciously or only instinctively, Williamson understood that molecular reality could best be grasped and explored scientifically using vivid mental images, the very sort that Kopp would later por-... 

Butlerov emphatically stated that it was not yet possible to determine actual physical molecular reality "chemistry, which only deals with bodies in a state of transformation, is powerless to judge this mechanical structure, as long as physical investigations are not brought to bear on the question." However,... 

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