Stereochemistry and Vitalism

Abstract

IT appears to me that Prof. Kipping and Mr. Pope unintentionally attribute to me opinions which I have never expressed, and which I do not hold. I never for a moment imagined that in each separate crystallisation—either of molecularly symmetric substances which, like sodium chlorate, may form either right-handed or left-handed crystals, or of the externally compensated mixture of dextro and laevo-rotatory sodium ammonium tartrates, in which the asymmetry is molecular—equal amounts of the two kinds of crystals would necessarily be deposited. I never thought of this equality as holding good, except as the mean of a great number of experiments. In my address, when referring to Messrs. Kipping and Pope's results obtained with sodium chlorate, I therefore used the expression “on the average.” Besides, I was acquainted with Landolt's experiments on the subject, which prove the same thing. In the case of the dextro- and laevo-rotatory sodium ammonium tartrates, the Pasteur-Gernez method of separating these by starting the crystallisation with a crystal of one of the two kinds, and Jungfleisch's experiments, to which I will refer more fully later on, were sufficient to make me aware of the influence of initial bias on crystallisation, and to prevent me from expecting equality, except as a mean result.