Optical rotatory power. Part IV.-rotatory dispersion of Bornyl and Menthyl Zanthates, especially in the region of absorption

Abstract

During a period of over 20 years, investigations have been carried out by one of us with a view to determining the form of the curve of rotatory dispersion, e.g., in the cases of quartz* and of a large number of typical organic compounds. These measurements were always made within the range of wave-lengths for which the medium under examination was completely transparent, since only under these conditions could the precision of the measurements be raised to a maximum by increasing the concentration of the optically-active compound and the length of the column traversed in the polarimeter. The general result has been to prove that the equation a = 2 f 2 , by which DRUDE in 1899 proposed to represent the optical rotatory power of transparent media, can be used to express the rotatory dispersion of compounds of every available type, up to the limits set by the experimental errors and by the range of transparency of the medium.