The effect of pressure up to 1800 kg/cm2 on the refractive indices of ethyl alcohol, water, and five intermediate aqueous solutions of alcohol at 25°C, was measured for the Hg arc lines of wave-lengths 579, 546, 436, and 406 mμ. There is an approximate decrease of 0.6 to 1 percent in the Lorentz-Lorenz “constant,” 0.1 to 0.45 percent deviation in the Gladstone and Dale “constant,” and 0.2 to 0.6 percent deviation in the empirical Eykman formula. It is concluded that with none of these formulae can the compressions of the solutions be computed from the refractive-index measurements with any great accuracy.
The specific refractions of Gladstone and Dale are found most suitable for a mixture formula which holds as well through the pressure range of 1500 atmos. as at atmospheric pressure.
Compressions calculated from refraction formulae are found to be a linear function of the observed compressions of the solutions. An equation is given which reproduces with great precision the refractive indices of alcohol, water, and their mixtures; its logartihmic term is the same as that in the Tait equation for compressibilities, and the part containing the refractive indices involves the same function which appears in the formulae of Gladstone and Dale, Lorentz-Lorenz, etc.
© 1947 Optical Society of AmericaFull Article | PDF Article
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