Studies of the processes operative in solutions. XXVII.—The causes of variation in the optical rotatory power of organic compounds and of anomalous rotatory dispersive power

Abstract

Biot, the distinguished French physicist, to whose genius we owe the discovery, in 1815, of the property now spoken of as optical rotatory power, made the further discovery that certain substances in solution, notably tartaric acid, offer an exception to the rule that the deviation which a polarised ray undergoes in its passage through a liquid is greater the shorter the wave-length. The precise manner in which variation takes place was established by Arndtsen, who determined the rotatory power of solutions of tartaric acid using light of the refrangibility of the lines c , D, E, b , F, e of the solar spectrum. In calling attention to these observations, in the article “Light” in the third Supplement of Watts’ ‘Dictionary of Chemistry’, published in 1881 one of us pointed out (p. 1208) that—