The British Association: Reports


    Report of the Committee, consisting of Dr. J. H. Gladstone, Dr. W. R. E. Hodgkinson, Mr. W. Carleton Williams, and Dr. P. P. Bedson (secretary), appointed for the purpose of investigating the Method of Determining the Specific Refraction of Solids from their Solutions.—Mr. P. P. Bedson, D.Sc, read the Report, and stated that the object of this report was to submit to further examination the method proposed some years ago by Messrs. Gladstone and Dale. According to this method the specific refraction of a solid may be deduced from that of a solution containing it, provided the specific refraction of the solvent is known, as also that of the solution and the composition of the solution. The experiments, of which an account is given in the report, appear to confirm this statement of the above-mentioned authors. The first case examined was that of liquid phenol. Its specific refraction for a ray of light of infinite wave length was determined at 40° and 45°. The values obtained for the specific refraction of liquid phenol at 40° and 45°, viz., .4850 and .4848, are closely approximate to that obtained by Brühl (Journ. Chem. Soc., abst., 1880, p. 782) for phenol at 20°, viz., .4862. Further, these results agree very well with the mean of the specific refractions obtained from the alcoholic and acetic acids solutions. The specific refraction of rock-salt in the solid state has also been determined and compared, with its specific refraction as deduced from its aqueous solutions; and it was found that the specific refraction obtained from the aqueous solution is substantially the same as that obtained from a prism of rock-salt. Further, the specific refractions of fused borax and boric acid have been determined, and in these cases also the specific refraction obtained from their aqueous solutions was found to be approximately the same as the specific refractions of fused borax and boric acid. The indices of fused borax and of fused boric acid were determined by means of prisms of these materials, which were cast in a mould of silver plates and afterwards ground and polished.

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    The British Association: Reports. Nature 24, 462–463 (1881).

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