Abstract
LONDON. Society of Public Analysts, Dee. 4.—A. P. Laurie: methods of examining pictures. An outline was given of the composition of the different pigments used for old illuminated MSS. and oil paintings, and methods of sampling by means of a micro-borer and examination by means of a microscope polariscope were described; a summary of micro-chemical tests the various classes of pigments was given. The of X-ray photography and ultra-violet rays was discussed, and it was shown how an examination of brush strokes in an oil painting, considered in conjunction with the chemical and optical properties the pigments, enabled a judgment to be formed as whether the whole work had been produced in one studio and at the same period.—S. Glasstone and C. Speakman: The quantitative analysis of mixtures nickel and cobalt. Electrometric titrations of nickel and cobalt solutions with potassium cyanide, with nickel and cobalt indicator-electrodes, respectively, have established the soundness of the theoretical basis of the Rupp and Pfennig method of determining these metals. A modified iodimetric method has also been developed for determining small amounts of cobalt in the presence of nickel.—J. C. Baird and H. Prentice: The changes with age of the hydrogen concentration of egg white and egg yolk. Determinations of hydrogen ion concentration by means quinhydrone electrode indicated that the normal pH value of fresh egg white is approximately 8.6, that there is a rapid rise in the course of the week of storage to a level of about pH 9.0, at which figure the reaction remains fairly constant. The fresh yolk has a reaction of approximately pH 6.0, which in the course of ten weeks rises to about 6.2. refractive index of the egg white is constant at about 1.360.
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Societies and Academies. Nature 124, 969–971 (1929). https://doi.org/10.1038/124969a0
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DOI: https://doi.org/10.1038/124969a0