Perrins

Brownian movement The rapid and random movement of particles of a colloidal sol, observed brightly lit against a dark ground. First observed with a pollen suspension. The Brownian movement is due to the impact on the dispersed particles of the molecules of the dispersion medium. As the particles increase in size, the probability of unequal bombardment from different sides decreases, and eventually collisions from all sides cancel out and the Brownian movement becomes imperceptible at a particle size of about 3-4/z. From the characteristics of the movement, Perrin calculated Avogadro s number L. 

D. Leger, E. Mathieu and J. C. Perrin, Optical surface determmation usmg speckle correlation technique . Appl. Opt., Vol. 14, 872-877 (1975). 

Perrin J 1922 On the radiation theory of chemical action Trans. Faraday Soc. 17 546-72... 

Perrin C L and Dwyer T 1990 Appiioation of two-dimensionai NMR to kinetios of ohemioai exohange Chem. Rev. 90 935-67... 

These two reviews (Orrell et al and Perrin and Dwyer) cover the modem pulse and two-dimensional NMR teclmiques for studying exchange. 

Perrin J 1910 Mouvement brownien et molecules J. Physique, Parish 5-39... 

Perrin J, Leroy O and Bordage M C 1996 Cross-sections, rate constants and transport coefficients in silane chemistry Contr. Plasma Phys 36 3-49... 

Quantities, Wiley-Interscience, New York, 1976 D. D. Perrin, Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution, 2d ed., Pergamon Press, 1982. 

The spherical geometry assumed in the Stokes and Einstein derivations gives the highly symmetrical boundary conditions favored by theoreticians. For ellipsoids of revolution having an axial ratio a/b, friction factors have been derived by F. Perrin, and the coefficient of the first-order term in Eq. (9.9) has been derived by Simha. In both cases the calculated quantities increase as the axial ratio increases above unity. For spheres, a/b = 1. 

R/Ro)soiv(f/fo)ellip = n + (mib/m2)(P2/Pi)] (f/fo)eiiip-Briefly justify this expansion of the (f/fo oiv factor. Assuming these particles were solvated to the extent of 0.26 g water (g protein)", calculate (f/fo)eiHp-For prolate ellipsoids of revolution (b/a < 1), Perrin has derived the following expression ... 

D. D. Perrin and co-workers. Purification ofEaboratory Chemicals Pergamon Press, New York, 1966, p. 56. 

These buffers are suitable for use in obtaining ultraviolet spectra. Alternatively, for a set of accurate buffers of low, but constant, ionic strength (I = 0.01) covering a pH range 2.2 to 11.6 at 20°, see Perrin Aust J Chem 16 572 1963. "In 100 mL means that the solution is made up to 100 mL with pure water. 

D.D. Perrin, Dissociation Constants of Organic Bases in Aqueous Solution, Butterworths, London, 1965 and Supplement 1972. 

D. D. Perrin and B. Dempsey, Buffers for pH and Metal Ion Control, Chapman and Hall, London, 1974. 

Xanthopterin monohydrate (2-amino-4,6-dihydroxypteridine, 2-amino-pteridin-4,6(lff,5ff)-dione) [5979-01-1 (H2O), 119-48-8 (anhydr)] M 197.2, m <300", pK, 1.6 (basic), pKj 6.59 (acidic), PK3 9.31 (acidic)(anhydrous species), and pKj 1.6 (basic), pK2 8.65 (acidic), PK3 9.99 (acidic)(7,8-hydrated species). Purification as for isoxanthopterin. Crystd by acidifying an ammoniacal soln, and collecting by centrifugation followed by washing with EtOH, ether and drying at 100° in vacuo. Paper chromatography Rp 0.15 ( -PrOH, 1% aq NH3, 2 1), 0.36 ( -BuOH,AcOH, H2O, 4 1 1) and 0.47 (3% aq NH3). [Inoue and Perrin J Chem Soc 260 7962 Inoue Tetrahedron 20 243 I964 see also Blakley Biochemistry of Folic Acid and Related Pteridines North Holland Publ Co, Amsterdam 1969.]... 

It is with much sadness that Dr Douglas D. Perrin was unable to participate in the preparation of the present edition due to illness. His contributions towards the previous editions have been substantial, and his drive and tenacity have been greatly missed. 

During the early years of physieal ehemistry, Ostwald did not believe in the existence of atoms... and yet he was somehow ineluded in the wild army of ionists. He was resolute in his scepticism and in the 1890s he sustained an obscure theory of energetics to take the place of the atomic hypothesis. How ions could be formed in a solution containing no atoms was not altogether clear. Finally, in 1905, when Einstein had shown in rigorous detail how the Brownian motion studied by Perrin could be interpreted in terms of the collision of dust motes with moving molecules (Chapter 3, Section 3.1.1), Ostwald relented and publicly embraced the existence of atoms. 

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

---